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A new old 1984 244 GL automatic

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Old Jul 22nd, 2020, 19:04   #21
Othen
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Next on the to-do list: Coolant flush, another engine oil change, replace all belts, rear axle oil change, ignition system check/adjust, and after a few miles, go over everything again and check all adjustments.

How are you getting on with that 244? Did you get the carburettor, leaks, transmission, ignition timing sender etc all sorted?

I was looking at the carburettor on the RB today (a Peirburg 175CD - sort of similar to yours) and had an idea that might completely get rid of the drop in revolutions when one puts the auto box into gear. It looks like your car had an anti-dieseling solenoid (as does mine). I was thinking that instead of just switching the solenoid when the ignition is turned on, it could be switched (by the starting inhibitor switch - backwards though, so there is a signal when the car is in gear) that would then open the valve and use the solenoid circuit in the carburettor to increase the fuel/air mix a bit - increasing the engine speed.

The anti-dieseling circuit probably wouldn’t do that job any more, in that one would have to use just the idle circuit to set the tick-over. speed in P or N

I might try it out on the RB.

Alan

Last edited by Othen; Jul 22nd, 2020 at 19:56. Reason: Addition.
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Old Jul 24th, 2020, 18:19   #22
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Many thanks, DW42, your estate looks great as well!

Quote:
If your transmission has a drain plug then it will be a BW35, not BW55, no issue, they do the same thing - the drain plug makes partial changes easier (the BW55 doesn't have one so I use a pump, does the same thing).
It could be a BW35, I have no way of confirming with the plate missing! The Haynes book says that from a certain date onwards, all automatic transmissions had a drain plug fitted, but the BW5/AW70 plug and washer look different.

Quote:
Why not fix the pan gasket with a proper one now, it will eliminate one source of leaking ATF so you can narrow down the list of suspects?
Well, the proper gasket needs to arrive, which may take a while… Until then I will have most likely done another round or two of partial ATF drains.

Quote:
Oil/ATF leaks are not really acceptable these days - so you should fix all of them (actually it is quite satisfying to achieve a leak free red block Volvo). Just be methodical and chip away it them until they are all fixed, generally it is just replacing gaskets and seals - all pretty easy.
I agree, my other classics have all been running leak-free for many years now. This is where I want to get with this one as well. I’m getting very close, see below.

Quote:
I used water as a coolant in the RB until I was sure everything was working okay (getting rid of EG is much more difficult than water), but it isn't 40C here in England!
The cooling system is working quite good, especially considering the temperature. I flushed it and refilled with fresh antifreeze, 50/50 with distilled water. Still waiting for the thermostat to arrive, but the existing one still works well. Any idea what there are three thermostat temperatures listed (82/88/92)? What does it depend on? Engine type? Accessories? Temperatures in the country where they were exported? No idea which one is in mine, I will check when I have the new one and a few seals. Perhaps in a few months along with another flush. Given that there are different metals in contact with the coolant, I wouldn’t want to run it with plain water to avoid differential corrosion. Plenty of gunk came out when I flushed it. The drain **** with hose nipple is really convenient, I was able to drain it without making a mess, into a bucket, which was promptly hidden away before the local cats take interest. I will take it to a disposal facility in a 20L canister I have for this purpose, so getting rid of it is not much of an issue.

Quote:
I have gone back to 20W50 with the RB and found it works much better than synthetic oils (the main seal weep has completely disappeared - saving me a messy job).
I’m divided about this. I’ve been running plenty of other engines on 20W/50 for years, but the Volvo book states that 20W/40 should not be used much below freezing. On the other hand, 10W/40 is given an upper limit of 40 degree C which is often exceeded here in the hot months, but we do get -15 degree celsius in the coldest months (as you may have guessed by the B17A engine and LHD, I’m currently stuck in Greece and the pandemic will keep me here for a while longer. I’ve driven from the UK to Greece and back 25 time, back when I was younger and healthier, but I hope I don’t have to do it anytime soon again!).
Some years ago I saw how long it took for the oil pressure to go up in a slant-4 with an oil pressure gauge, at -10 degree Celsius and with my favourite 20W/50, and am skeptical about its winter performance. On the other hand, it worked perfect from 0 up to as hot as it can get, and if the Slant-4 can handle it, I think the Volvo red blocks must be fine with it as well.

The engine on mine doesn’t have any leaks, which is good. So, currently running 10W/40 (I had plenty for another car, so it came in handy), but will probably try 20W/50 at some point. I wouldn’t mind an oil pressure gauge as well, an original Volvo item would be great, but still have plenty of things to sort out before worrying about that.

Quote:
There should be some resistance pulling out the plunger, it sounds like the diaphragm may be leaking if the ATF level has gone down.
The first time I topped it up, it lost it pretty fast. The second time it was slower. By the third time, it seems to stay. It is not the diaphragm, but an o-ring on the adjuster screw. With a bit of luck, the ATF will cause it to swell up, so I can delay the stripdown until the diaphragms arrive. It must have dried up completely in 18 years of collecting dust.

Quote:
The ignition advance is clearly wrong, change the vacuum hose and see if that works - if not you might have to strip the distributor to free off whatever is stuck (not a hard job). At this stage I'd be tempted (if I were you, which I am not) to change the internals of the distributor for a solid state electronic unit and dispense with the points and condenser. I think the cost is about £100 - but then you would never have to make an adjustment again.
I opened up the distributor, lubricated everything and verified that it all moves as it should. Couldn’t test the vacuum advance diaphragm yet, but the distributor itself is good. The dwell angle meter works again and I measured 63 degrees. Acceleration is good, so I think it won’t be the vacuum advance.

I think I’ll keep the points for now. I do have a complete Bosch distributor with the Lumenition system, from another vehicle, so I can try it out, but I did run two otherwise identical Slant-4 engines, one with the Lumenition and the other with a Delco-Remy points setup. I enjoyed the Delco much more and only had one points-related issue in over 10 years. The Lumenition tended to die each time the under-bonnet temperatures rose too high in the summer. Only temporarily, the cure was to open the bonnet, wait 10-15 minutes and drive again, taking care not to get stuck in traffic! I did not see much difference in performance between the two systems. The points did need frequent adjustment, but it was the system I trusted most. I always carried a couple of sets of points and condensers just in case, and drove from one end of Europe to the other with it on multiple occasions.

Quote:
I really do wonder why you think it is worth using though, all it is telling you is where two points are on the flywheel (the bit of plastic on the cam cover does that with no electronics).
Most, if not all, the vehicles I’ve had up to now only had the strobe method as an option. Of all the work done on vehicles, the timing adjustment using a strobe is the one I have always greatly disliked. I just find it very unpleasant. If I can finally get to skip this part and do it by more pleasant means, I would at least give it a try.

Quote:
Fortunately bits are quite cheap and the car is really simple, so you will soon have it all sorted.
I made quite some progress: All leaks fixed (apart from the messy goo in the transmission pan, but this is not a big deal and will be sorted as soon as the gasket arrives)! The biggest one was the right steering rubber bellows. I am very confused about that. I’m not sure of it was the wrong bellows, but it was wrongly fitted. However, the right side housing does not have a fitting for the connecting pipe! The bellows has a hole in which the steel pipe goes! I refitted it correctly and there’s no leak anymore. But I do wonder which power steering gear I have! It doesn’t look like what the Volvo book shows!



Could it be that the right side housing is missing? Or is it a different type of steering rack?

Also drained and refilled the rear axle with GL-5 axle oil. It is the 3.91:1 Type 1030, as far as I could tell.
I did a part-drain of the PAS fluid as well. What is the purpose of the steel pipe going into the bellows? A return line?

Finally, as the the idle in D was still rough, I checked carefully all the ignition parts I had assumed to be ok: I found a bad contact on HT lead #4, fixed it, and adjusted the carb.

It started really good, idling at 1200 rpm and only dropping to 800 rpm or so in D, really smooth. Went for a drive and noticed that as soon as I stop for too long in D, the idle speed drops. This does not happen in N.
So, it is now an intermittent issue, which I assume has to do with aging vacuum hoses (too many of them) and rising under-bonnet temps when standing still. If I have driven at some speed and stop for 15 seconds, then start again, all is well. But when I took a few minutes to back up into the garden, the idle speed just went lower and lower until it just stalled. Starts instantly again, but really doesn’t like the heat. I bet they didn’t have 40 degree Celsius summers in Sweden! At night it is much better, 28 degrees C ambient. Then again, I also don’t work well anymore at 40 degrees C. Well, below 500 rpm it starts misfiring. If I give some gas, all is well. Shift to N and it roars up to 1200 rpm again, super stable.

Quote:
That's a nice car, especially with the "Turbo" grille; most 240s have a "waterfall" style one.
Thanks! I hadn’t realised this is the Turbo grille!

Quote:
The carb is, or should be, a Stromberg 175 CD or 175 CD2. Avoid the Pierburg CDSUs if possible as they are more prone, in my experience at least, to idle at whatever speed they feel like. (I had a B21A with BW35 box that idled at a smooth 500rpm one day and a rough 1000rpm the next, and never really got to the bottom of why it did so.) Plus the pure Stromberg parts are still available at sensible prices. A needle and jet for a Pierburg cost £25 each back in the 1980s, whereas a new needle for a Stromberg was about £5!
The carb is the Solex 175CD, which is a Stromberg 175CD that just says Solex on it. I think all the Stromberg parts fit.

Quote:
Those wheel nuts with the dimple sticking out are the older type and are probably the right ones for your car.900/700 s have a different thread.Later 240 GLT ones are big and chunky but would do.
Jim, I just realised that the chrome nuts with the dimple are just covers! The real nut looks much less exciting underneath! So, the boring-looking nuts are the ones whose covers fell off!! I wasn’t there when they changed the tyres, or I would have seen it earlier!

Quote:
700/900-series wheels will fit a 200- series car, but the wheel nuts most definitely will not: 200s use imperial thread wheel nuts, 700/900 wheel nuts are metric. The wheel nuts are a mix; all are correct but not together on the same wheel, so it might be worth swapping them around to make it look more aesthetically pleasing or fitting the odd ones in the same position on each wheel - e.g. adjacent to/opposite the valve. It is possible that the car once had locking wheel nuts that have since been replaced with ordinary ones.

Imperial threads on a Volvo? I guess an SAE standard? I will check/measure and see what exactly is going on there. I might need to get some more covers, if I can find them.

All in all, I’m really enjoying this car. It’s easy to work on and seems very solidly built, which is exactly what I wanted.
It is very comfortable to drive and offers a very smooth ride.

I discovered a small crack on the exhaust muffler while I was working on the rear axle, so another thing to sort out there. I guess this will sort out the annoying rattle coming from there. I will also need to get a good length of fresh vacuum hose and replace all vacuum connections just to eliminate this as a source of intermittent trouble.
It is either a hose loosening up with too much heat, or an incorrect/faulty Thermostat. I will replace it soon and see what was in there.

Regarding the wheels, I was also wondering if they were meant to have centre caps covering the wheel nuts. I can’t say I like the wheels that much, but I’m not too picky about wheels. Even some plain steels are fine with me, if nicely powder coated and not rusty. For now they will do. But the best thing about alloys, which is the visibility of the brake disks and pads through larger openings, for ease of inspection, is not fully exploited with these wheels!

Finally, some questions about parts as the quest continues:

1) What do you guys use for HT leads? Do you try to match the resistance specs or just anything of the correct length? I’d like to replace mine before the wet months arrive.

2) What do you use for sparkplugs? Apparently, Bosch still makes the W7DC, but in Russia, and there are a lot of negative comments online about their quality. Any luck with other brands/types?

3) How about the ignition coil? Mine still has the (perhaps originally fitted) Bosch 0 221 122 006, which is not easily obtainable nowadays. Is it worth looking for an original coil to have as a spare or are there any other types that work well and are easily available?

4) Does anybody have any part number for the contact breaker points and condenser?

5) Any timing belt preferences? Gates? Hutchinson? Bosch? Other? Mine currently has Gates fitted, which still looks good, although about 8 years old.
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Old Jul 24th, 2020, 18:27   #23
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Power steering gear type can gear. Some more pictures. Mine does not look like that.

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Old Jul 24th, 2020, 21:05   #24
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Many thanks, DW42, your estate looks great as well!



It could be a BW35, I have no way of confirming with the plate missing! The Haynes book says that from a certain date onwards, all automatic transmissions had a drain plug fitted, but the BW5/AW70 plug and washer look different.



Well, the proper gasket needs to arrive, which may take a while… Until then I will have most likely done another round or two of partial ATF drains.



I agree, my other classics have all been running leak-free for many years now. This is where I want to get with this one as well. I’m getting very close, see below.


The cooling system is working quite good, especially considering the temperature. I flushed it and refilled with fresh antifreeze, 50/50 with distilled water. Still waiting for the thermostat to arrive, but the existing one still works well. Any idea what there are three thermostat temperatures listed (82/88/92)? What does it depend on? Engine type? Accessories? Temperatures in the country where they were exported? No idea which one is in mine, I will check when I have the new one and a few seals. Perhaps in a few months along with another flush. Given that there are different metals in contact with the coolant, I wouldn’t want to run it with plain water to avoid differential corrosion. Plenty of gunk came out when I flushed it. The drain **** with hose nipple is really convenient, I was able to drain it without making a mess, into a bucket, which was promptly hidden away before the local cats take interest. I will take it to a disposal facility in a 20L canister I have for this purpose, so getting rid of it is not much of an issue.



I’m divided about this. I’ve been running plenty of other engines on 20W/50 for years, but the Volvo book states that 20W/40 should not be used much below freezing. On the other hand, 10W/40 is given an upper limit of 40 degree C which is often exceeded here in the hot months, but we do get -15 degree celsius in the coldest months (as you may have guessed by the B17A engine and LHD, I’m currently stuck in Greece and the pandemic will keep me here for a while longer. I’ve driven from the UK to Greece and back 25 time, back when I was younger and healthier, but I hope I don’t have to do it anytime soon again!).
Some years ago I saw how long it took for the oil pressure to go up in a slant-4 with an oil pressure gauge, at -10 degree Celsius and with my favourite 20W/50, and am skeptical about its winter performance. On the other hand, it worked perfect from 0 up to as hot as it can get, and if the Slant-4 can handle it, I think the Volvo red blocks must be fine with it as well.

The engine on mine doesn’t have any leaks, which is good. So, currently running 10W/40 (I had plenty for another car, so it came in handy), but will probably try 20W/50 at some point. I wouldn’t mind an oil pressure gauge as well, an original Volvo item would be great, but still have plenty of things to sort out before worrying about that.



The first time I topped it up, it lost it pretty fast. The second time it was slower. By the third time, it seems to stay. It is not the diaphragm, but an o-ring on the adjuster screw. With a bit of luck, the ATF will cause it to swell up, so I can delay the stripdown until the diaphragms arrive. It must have dried up completely in 18 years of collecting dust.



I opened up the distributor, lubricated everything and verified that it all moves as it should. Couldn’t test the vacuum advance diaphragm yet, but the distributor itself is good. The dwell angle meter works again and I measured 63 degrees. Acceleration is good, so I think it won’t be the vacuum advance.

I think I’ll keep the points for now. I do have a complete Bosch distributor with the Lumenition system, from another vehicle, so I can try it out, but I did run two otherwise identical Slant-4 engines, one with the Lumenition and the other with a Delco-Remy points setup. I enjoyed the Delco much more and only had one points-related issue in over 10 years. The Lumenition tended to die each time the under-bonnet temperatures rose too high in the summer. Only temporarily, the cure was to open the bonnet, wait 10-15 minutes and drive again, taking care not to get stuck in traffic! I did not see much difference in performance between the two systems. The points did need frequent adjustment, but it was the system I trusted most. I always carried a couple of sets of points and condensers just in case, and drove from one end of Europe to the other with it on multiple occasions.



Most, if not all, the vehicles I’ve had up to now only had the strobe method as an option. Of all the work done on vehicles, the timing adjustment using a strobe is the one I have always greatly disliked. I just find it very unpleasant. If I can finally get to skip this part and do it by more pleasant means, I would at least give it a try.



I made quite some progress: All leaks fixed (apart from the messy goo in the transmission pan, but this is not a big deal and will be sorted as soon as the gasket arrives)! The biggest one was the right steering rubber bellows. I am very confused about that. I’m not sure of it was the wrong bellows, but it was wrongly fitted. However, the right side housing does not have a fitting for the connecting pipe! The bellows has a hole in which the steel pipe goes! I refitted it correctly and there’s no leak anymore. But I do wonder which power steering gear I have! It doesn’t look like what the Volvo book shows!

Could it be that the right side housing is missing? Or is it a different type of steering rack?

Also drained and refilled the rear axle with GL-5 axle oil. It is the 3.91:1 Type 1030, as far as I could tell.
I did a part-drain of the PAS fluid as well. What is the purpose of the steel pipe going into the bellows? A return line?

Finally, as the the idle in D was still rough, I checked carefully all the ignition parts I had assumed to be ok: I found a bad contact on HT lead #4, fixed it, and adjusted the carb.

It started really good, idling at 1200 rpm and only dropping to 800 rpm or so in D, really smooth. Went for a drive and noticed that as soon as I stop for too long in D, the idle speed drops. This does not happen in N.
So, it is now an intermittent issue, which I assume has to do with aging vacuum hoses (too many of them) and rising under-bonnet temps when standing still. If I have driven at some speed and stop for 15 seconds, then start again, all is well. But when I took a few minutes to back up into the garden, the idle speed just went lower and lower until it just stalled. Starts instantly again, but really doesn’t like the heat. I bet they didn’t have 40 degree Celsius summers in Sweden! At night it is much better, 28 degrees C ambient. Then again, I also don’t work well anymore at 40 degrees C. Well, below 500 rpm it starts misfiring. If I give some gas, all is well. Shift to N and it roars up to 1200 rpm again, super stable.
Thanks! I hadn’t realised this is the Turbo grille!
The carb is the Solex 175CD, which is a Stromberg 175CD that just says Solex on it. I think all the Stromberg parts fit.



Jim, I just realised that the chrome nuts with the dimple are just covers! The real nut looks much less exciting underneath! So, the boring-looking nuts are the ones whose covers fell off!! I wasn’t there when they changed the tyres, or I would have seen it earlier!
Imperial threads on a Volvo? I guess an SAE standard? I will check/measure and see what exactly is going on there. I might need to get some more covers, if I can find them.

All in all, I’m really enjoying this car. It’s easy to work on and seems very solidly built, which is exactly what I wanted.
It is very comfortable to drive and offers a very smooth ride.

I discovered a small crack on the exhaust muffler while I was working on the rear axle, so another thing to sort out there. I guess this will sort out the annoying rattle coming from there. I will also need to get a good length of fresh vacuum hose and replace all vacuum connections just to eliminate this as a source of intermittent trouble.
It is either a hose loosening up with too much heat, or an incorrect/faulty Thermostat. I will replace it soon and see what was in there.

Regarding the wheels, I was also wondering if they were meant to have centre caps covering the wheel nuts. I can’t say I like the wheels that much, but I’m not too picky about wheels. Even some plain steels are fine with me, if nicely powder coated and not rusty. For now they will do. But the best thing about alloys, which is the visibility of the brake disks and pads through larger openings, for ease of inspection, is not fully exploited with these wheels!

Finally, some questions about parts as the quest continues:

1) What do you guys use for HT leads? Do you try to match the resistance specs or just anything of the correct length? I’d like to replace mine before the wet months arrive.

2) What do you use for sparkplugs? Apparently, Bosch still makes the W7DC, but in Russia, and there are a lot of negative comments online about their quality. Any luck with other brands/types?

3) How about the ignition coil? Mine still has the (perhaps originally fitted) Bosch 0 221 122 006, which is not easily obtainable nowadays. Is it worth looking for an original coil to have as a spare or are there any other types that work well and are easily available?

4) Does anybody have any part number for the contact breaker points and condenser?

5) Any timing belt preferences? Gates? Hutchinson? Bosch? Other? Mine currently has Gates fitted, which still looks good, although about 8 years old.
My word, that was a comprehensive reply.

Well done, your motor car is coming along well.
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Old Jul 26th, 2020, 12:13   #25
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How are you getting on with that 244? Did you get the carburettor, leaks, transmission, ignition timing sender etc all sorted?

I was looking at the carburettor on the RB today (a Peirburg 175CD - sort of similar to yours) and had an idea that might completely get rid of the drop in revolutions when one puts the auto box into gear. It looks like your car had an anti-dieseling solenoid (as does mine). I was thinking that instead of just switching the solenoid when the ignition is turned on, it could be switched (by the starting inhibitor switch - backwards though, so there is a signal when the car is in gear) that would then open the valve and use the solenoid circuit in the carburettor to increase the fuel/air mix a bit - increasing the engine speed.

The anti-dieseling circuit probably wouldn’t do that job any more, in that one would have to use just the idle circuit to set the tick-over. speed in P or N

I might try it out on the RB.

Alan
Alan, I would advise against re-purposing the “anti-dieseling” solenoid. On the Volvos and the side-draught carburetors, these open a channel from the air side of the throttle valve to the engine side, which has an effect very similar to opening the throttle valve by the same amount (by pressing the accelerator pedal for example). On down-draught carburetors, the solenoids block off the idle jet when the ignition is switched off. In practice, their main purpose is not to prevent dieseling, as this shouldn’t really be an issue in a properly set up spark ignition engine: The compression is not high enough for compression-ignition of the fuel/air mix, the ignition is switched off so there is no spark, and the cylinder head/valves/etc should really not get that hot to ignite the mix. But what is a real problem is that the passive “flywheeling” of the engine to a halt still creates vacuum on the intake side, which sucks in a small amount of fuel/air. This does not get ignited (normally), but remains in the cylinders, washing down the cylinder walls and eventually ending up in the sump, contaminating the engine oil and greatly increasing wear next time the engine is started. The solenoids reduce the amount of fuel ending up in the cylinders after the ignition is switched off. On down-drought carbs, the solenoids have nothing to do with idle speed (at least until they break).

But in our Volvo, the channel they control is adjustable. This is best left as is, but your excellent idea can be better implemented through the use of an A/C bypass solenoid (a second one, in my case).
The idle bypass channel can be set for 900 rpm at idle in N and the “transmission compensation” solenoid can be adjusted for 900 rpm with the transmission in gear, via the starter inhibitor switch with an inverted state (via a logic gate or just a simple relay). Then the idle speed would remain unconditionally stable.

In fact, this is what Volvo should have done in the first place! Now, where do we get a couple of extra A/C bypass solenoids of the adjustable type? It would take a certain amount of time until the solenoid opens the channel and more fuel/air reaches the cylinders, but it would also take a certain amount of time for the transmission to actually engage the epicyclic gearing, loading up the engine, so with a bit of luck, this could be very smooth!

This is something I’d gladly add to my 244! These are mounted remotely and are hooked up to the intake manifold and carb via fuel hoses (for vacuum hoses, but I prefer if they are rated to withstand fuel since it will be the fuel/air mix that they will be passing).

I actually thought that this was how it was meant to work when I first bought the car, and assumed that the solenoid may have given up, but after looking everywhere, I was unable to find such an arrangement for the transmission (confirmed by the manuals). It is only there for the idling and A/C.
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Old Jul 26th, 2020, 14:22   #26
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Alan, I would advise against re-purposing the “anti-dieseling” solenoid. On the Volvos and the side-draught carburetors, these open a channel from the air side of the throttle valve to the engine side, which has an effect very similar to opening the throttle valve by the same amount (by pressing the accelerator pedal for example). On down-draught carburetors, the solenoids block off the idle jet when the ignition is switched off. In practice, their main purpose is not to prevent dieseling, as this shouldn’t really be an issue in a properly set up spark ignition engine: The compression is not high enough for compression-ignition of the fuel/air mix, the ignition is switched off so there is no spark, and the cylinder head/valves/etc should really not get that hot to ignite the mix. But what is a real problem is that the passive “flywheeling” of the engine to a halt still creates vacuum on the intake side, which sucks in a small amount of fuel/air. This does not get ignited (normally), but remains in the cylinders, washing down the cylinder walls and eventually ending up in the sump, contaminating the engine oil and greatly increasing wear next time the engine is started. The solenoids reduce the amount of fuel ending up in the cylinders after the ignition is switched off. On down-drought carbs, the solenoids have nothing to do with idle speed (at least until they break).

But in our Volvo, the channel they control is adjustable. This is best left as is, but your excellent idea can be better implemented through the use of an A/C bypass solenoid (a second one, in my case).
The idle bypass channel can be set for 900 rpm at idle in N and the “transmission compensation” solenoid can be adjusted for 900 rpm with the transmission in gear, via the starter inhibitor switch with an inverted state (via a logic gate or just a simple relay). Then the idle speed would remain unconditionally stable.

In fact, this is what Volvo should have done in the first place! Now, where do we get a couple of extra A/C bypass solenoids of the adjustable type? It would take a certain amount of time until the solenoid opens the channel and more fuel/air reaches the cylinders, but it would also take a certain amount of time for the transmission to actually engage the epicyclic gearing, loading up the engine, so with a bit of luck, this could be very smooth!

This is something I’d gladly add to my 244! These are mounted remotely and are hooked up to the intake manifold and carb via fuel hoses (for vacuum hoses, but I prefer if they are rated to withstand fuel since it will be the fuel/air mix that they will be passing).

I actually thought that this was how it was meant to work when I first bought the car, and assumed that the solenoid may have given up, but after looking everywhere, I was unable to find such an arrangement for the transmission (confirmed by the manuals). It is only there for the idling and A/C.
Hi,

I have no prior knowledge of these types of carburettors (most of my experience is with motorcycles) - so I'm just going by what I read in the Volvo green book. As you may see from this screen shot, it describes the purpose as being to stop engine run-on (I always thought that meant dieseling) and says that in some markets the solenoids is re-purposed to increase engine speed for cars equipped with air conditioning (rare here in the UK):



... so, that is why i thought the purpose was anti-dieseling, and that is what gave me the idea of re-purposing it to compensate for transmission drag at tick-over. You are probably right though; I have no more experience than reading the book.

My Pierburg 175CD carburettor does not seem to have any channel built in to it for air conditioning compensation (that I can see, but again I'm just going from the book):



... it seems to have just the metering (throttle), idling and solenoid bypass circuits, so where would an air conditioning bypass solenoid plug in? I'm wondering whether such a solenoid would replace the adjuster screw for the anti dieseling circuit (that seems to be what is shown in drawing - but then the current fitted solenoid would have no effect (the channel being closed when the car is in P or N anyway).

If my carburettor has a suitable air conditioning circuit and if I can find a solenoid to fit, then I'd be really keen to see if I can get this to work as you have described - I'd even worked out how to use an ordinary 5 pin relay to provide a NOT gate control from the starter inhibitor switch. It does seem to me that if I just fitted a second solenoid to the place where the anti dieseling channel adjuster is now, then the two would be operating in series on the same channel, so the anti dieseling one would be superfluous (perhaps I have misunderstood something?).

I'd be really pleased to hear whether you think this might work - not because there is a problem that really needs fixing, but because it would be a really clever enhancement to the RB.

Alan

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Old Jul 26th, 2020, 23:16   #27
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Hi,

I have no prior knowledge of these types of carburettors (most of my experience is with motorcycles) - so I'm just going by what I read in the Volvo green book. As you may see from this screen shot, it describes the purpose as being to stop engine run-on (I always thought that meant dieseling) and says that in some markets the solenoids is re-purposed to increase engine speed for cars equipped with air conditioning (rare here in the UK):

... so, that is why i thought the purpose was anti-dieseling, and that is what gave me the idea of re-purposing it to compensate for transmission drag at tick-over. You are probably right though; I have no more experience than reading the book.

My Pierburg 175CD carburettor does not seem to have any channel built in to it for air conditioning compensation (that I can see, but again I'm just going from the book):



... it seems to have just the metering (throttle), idling and solenoid bypass circuits, so where would an air conditioning bypass solenoid plug in? I'm wondering whether such a solenoid would replace the adjuster screw for the anti dieseling circuit (that seems to be what is shown in drawing - but then the current fitted solenoid would have no effect (the channel being closed when the car is in P or N anyway).

If my carburettor has a suitable air conditioning circuit and if I can find a solenoid to fit, then I'd be really keen to see if I can get this to work as you have described - I'd even worked out how to use an ordinary 5 pin relay to provide a NOT gate control from the starter inhibitor switch. It does seem to me that if I just fitted a second solenoid to the place where the anti dieseling channel adjuster is now, then the two would be operating in series on the same channel, so the anti dieseling one would be superfluous (perhaps I have misunderstood something?).

I'd be really pleased to hear whether you think this might work - not because there is a problem that really needs fixing, but because it would be a really clever enhancement to the RB.

Alan
Hi again,

I've been thinking about this one, and have concluded that the anti-dieseling solenoid I have fitted to the RB probably modulates the idling channel, rather than the solenoid channel as I had previously assumed. It would seem (to me) that the solenoid valve terminal is not modulated, except by the screw which affects the idle speed (it is 2 turns out on my car - probably has been for the past 40 years). It would appear (to me) that on the 1975-77 B21a motors the valve on the carburettor was used as the anti-dieseling port, and perhaps as a by-pass for the A/C as well:



... but that for the 1978-84 motors the solenoid was moved to the manifold, leaving the solenoid channel in the carburettor more or less redundant.

Does my analysis sound right? If it is then that would leave the solenoid valve terminal on the carburettor (shown as #7 on this drawing):



... available for a second solenoid to be fitted, and more importantly able to modulate a separate channel to the anti dieseling solenoid.

Roger so far?

If I'm right (and I have not taken the carburettor or manifold off to check - I'm just working from drawings and logic) - then it would seem a fairly simple matter to:

a. adjust the idling channel (via the screw on the manifold) to set the tick-over at 900 RPM in P, with the screw on the solenoid valve terminal turned all the way in (so no assistance from the solenoid channel).

b. replace the screw adjuster in the solenoid valve terminal with a solenoid, probably from a 1975-77 B21a motor (finding one of those may be an issue).

c. create a control circuit using the starter inhibitor switch and a 5 pin relay to give 12v (and so open the solenoid fitted to the carburettor) when the car is in any gear.

That all seems quite easy - and was more of less where I was coming from with my first suggestion of using the anti dieseling solenoid as a transmission compensation by-pass, except I'd assumed at that time it was modulating the solenoid channel rather than the idling channel.

If it is as simple as I've suggested then I wonder why Volvo didn't do this 40 years ago? Volvo could have engineered out the effects of transmission drag at tick-over, which would have been pretty cool.

Acquiring a solenoid from a 1975-77 B21a motor that still works might be a challenge (I don't know yet, I have not looked). Another issue would be that the solenoid channel on the carburettor would no longer be adjustable, so the amount of boost given by opening that solenoid would be fixed - which might not exactly match the drag imposed by the transmission in a drive gear (I suppose one could affect some adjustment by perhaps changing the depth of the 1975-77 solenoid's plunger).

Do you think I have understood what is going on correctly and come to a sensible conclusion?

Alan

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Old Jul 29th, 2020, 15:58   #28
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Alan,
run-on and dieseling are indeed the same thing and I assume that the technical literature of the carburettor era called it as such for simplicity. I had long suspected that in an otherwise well-tuned engine, simply missing such a solenoid, run-on would be very unlikely, but what would certainly happen would be unburnt fuel remaining in the cylinder.
I got to test this theory several years ago, when on one of my long trips across Europe, the solenoid died in the middle of nowhere on a Saturday night (as they do). It was a down-drought Weber carburettor and the solenoid was meant to block the idle jet when the ignition was off and open it as soon as it was powered up. When it died, the idle jet remained permanently closed, so the engine refused to idle. I had to get going so I simply unscrewed the solenoid, sawed off the tip, and put it back in (you can’t leave it out, it will leak). This left the idle jet permanently open. All worked fine with no hint of run-on, ever, for thousands of miles until I could find a working solenoid. But the engine oil did smell a bit of petrol when I changed it. Not a big deal if you don’t do start/stop city driving. But if you do…

In engineering terms, even just two revolutions of the engine after switching off the ignition would be enough for each cylinder to complete an intake stroke, which would result in a total volume of fuel/air equal to your engine displacement. Assuming a perfect stoichiometric ratio, you can do the math to determine exactly how much fuel went in there in total, divided by the number of cylindres for a per-cylinder amount of fuel on litres (converted to ml for convenience). Some may be lost if a cylinder subsequently completes an exhaust stroke and some may evaporate out if any cylinder stops with a valve open, but most of it will remain where you wouldn’t want it to remain. Remember that the moving mass of a car engine is much more than a motorcycle engine and the only thing braking it fast once the ignition is off is intake vacuum and compression pressure. So it will do at least a couple of revolutions due to interia.

As for adding an extra solenoid to your Pierburg 175CD: I assume the idle bypass solenoid is not on the carburettor itself, but on the intake manifold (as it is on mine), which hooks up to the “idling channel” (#2, last screenshot you posted, or #6 on the one above right).

Does your carburettor still have the “solenoid valve channel” (#1 on the last screenshot), blocked off with a screw, as shown? If so, you can either directly fit the solenoid there (if you can find an adjustable solenoid that will fit or if it magically happens to give just the right rpm), saving you the extra plumbing, or alternatively you can install a nipple there (mine is set up this way) so you can run a hose to a remote solenoid, returning to any suitable part on the intake manifold (remembering that it will be fuel/air passing through, so you would want to only use fuel hose, not just plain vacuum hose!) I can try to shoot a few pictures of mine.

If you can’t find a suitable nipple, if you can remove the blocking screw, measure it up and send me a drawing (even hand-dawn), I can machine a fitting nipple for you. You need the two solenoids operating in parallel, not in series.
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Old Jul 29th, 2020, 16:09   #29
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Alan, just saw your previous post, my previous reply was to the one before. Yes, sounds like you have pretty much figured it out, very similarly to what I was talking about in my previous reply. The only major difference is that you do not actually have to use a solenoid in the carburettor channel, you can just use a nipple designed to connect to the air side of the solenoid channel while blocking off the engine side.
This seems to have been a standard arrangement for A/C, as in my motor. The A/C solenoid on my car is mounted on the bulkhead and does not actually pass fuel/air, it only acts as a vacuum control valve for a second, purely mechanical valve, mounted directly on a long metallic connector on the intake manifold. I assume this is to keep the fuel/air path shorter, requiring only one very short length of hose actually passing fuel/air, while eliminating any electrical wiring (spark/fire hazard?) in close proximity to perishable fuel/air channels. Seems reasonable and works well.

As for why Volvo didn’t originally do it that way, I can only assume that, as with most things, the reasons had more to do with economically-imposed rather than technologically-imposed limitations. It wasn’t just the cost of a bit of extra plumbing, but also figuring out how this should be implemented for all the different markets, different features (A/C, Pulseair, EGR, etc) as well as training the service personnel on maintenance and troubleshooting, for what was perhaps seen as only a small market share (automatics).

Regarding one of your previous posts about the possibility of the distributor vacuum advance, compensating for transmission loading, it is worth noting that the vacuum advance unit connects to the air side of the throttle valve, where the vacuum at idle is not enough to have much of an effect. It is on the engine side where the vacuum is strongest at idle, but the distributor/ignition timing is meant to advance at maximum load (wide open throttle), not at idle, hence the connection to the air side where vacuum increases as the throttle valve opens. So, this can’t have been thought of as a viable compensation system.
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Old Jul 29th, 2020, 22:31   #30
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Alan, just saw your previous post, my previous reply was to the one before. Yes, sounds like you have pretty much figured it out, very similarly to what I was talking about in my previous reply. The only major difference is that you do not actually have to use a solenoid in the carburettor channel, you can just use a nipple designed to connect to the air side of the solenoid channel while blocking off the engine side.
This seems to have been a standard arrangement for A/C, as in my motor. The A/C solenoid on my car is mounted on the bulkhead and does not actually pass fuel/air, it only acts as a vacuum control valve for a second, purely mechanical valve, mounted directly on a long metallic connector on the intake manifold. I assume this is to keep the fuel/air path shorter, requiring only one very short length of hose actually passing fuel/air, while eliminating any electrical wiring (spark/fire hazard?) in close proximity to perishable fuel/air channels. Seems reasonable and works well.

As for why Volvo didn’t originally do it that way, I can only assume that, as with most things, the reasons had more to do with economically-imposed rather than technologically-imposed limitations. It wasn’t just the cost of a bit of extra plumbing, but also figuring out how this should be implemented for all the different markets, different features (A/C, Pulseair, EGR, etc) as well as training the service personnel on maintenance and troubleshooting, for what was perhaps seen as only a small market share (automatics).

Regarding one of your previous posts about the possibility of the distributor vacuum advance, compensating for transmission loading, it is worth noting that the vacuum advance unit connects to the air side of the throttle valve, where the vacuum at idle is not enough to have much of an effect. It is on the engine side where the vacuum is strongest at idle, but the distributor/ignition timing is meant to advance at maximum load (wide open throttle), not at idle, hence the connection to the air side where vacuum increases as the throttle valve opens. So, this can’t have been thought of as a viable compensation system.
Many thanks for those comments. My apology - I seem to have slightly hijacked your thread - so I’ll try to bring this tangent to an end here (and maybe continue it in the Royal Barge thread).

I’ll start looking around for a solenoid that’s might work. If I find something then I think utilising the solenoid channel the way it was designed would be the best way to go.

On the vacuum advance bit: my theory about it ameliorating the effects of transmission drag came from an empirical test I did when I last set the ignition timing. As per normal I set the sparks at 15 degrees BTDC with the vacuum hose sealed off, then reconnected the hose and checked it again with the strobe when I adjusted the tickover in P - the advance had certainly increased; then with the motor in D (and the handbrake wedged on as tight as I could get it!) the load on the engine certainly increased and the advance increased a bit more. The amount of advance is clearly not enough to compensate for transmission drag - because the engine speed still drops by 150 RPM in D. I suppose what I should have done is try the experiment again with the vacuum hose plugged to see if the drop in engine speed was the same, but that didn’t occur to me at the time - so the test was not very scientific.

Anyway, I’m certainly not doubting you - you are very much more knowledgable than am I on this matter. My theory was a guess on my part.

Alan.

PS. I noticed your mention of numerous motoring trips across Europe - that reminded me of two similar (separate) journeys I made from Cyprus to England in the late 1980s. Both times I used (different) Mazda 323s, they were absolutely first rate cars for long trips - simple but absolutely reliable.
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