240 General: Ignition problem

[Othen]

Originally Posted by Bob 1967

Yes , i found the mark on the very bottom pully (right at the back) that lines up so its definitely the Auxiliary pully that's offending part.
I fully intend to change all belts ,tensioner and water pump all together ,just right not now. I've gotten the area cleaned and ready I slackened off the tensioner nut ready for tomorrow.
But as I now know the steps for removal it will make replacement of parts much simpler.

If some of you might remember ,when I bought the car it had the brake bleed nipples removed and replaced with bolts ! (All new calliper's and discs have been fitted since )
So a pully out of alignment doesn't surprise me, much.
Bob

One thing I forgot to mention Bob.

When you come to change the cam belt you will have to remove the auxiliary belt pulleys from the front of the crankshaft to get the old belt off and the new one on. This isn't a hard job (half a dozen small screws - about M6), but just to realign it you don't need that step. Once the belt is loose (off the camshaft and auxiliary sprockets) there is enough clearance to carefully move it around without disturbing the crank position. The TDC mark is on the bottom sprocket and engine case, you may just see it through the gap in this photo:



Pay particular attention to the cam belt tensioner when you take the belt off to realign it, that may have been the cause if the belt jumped a tooth (or even two). Like Bugjam said, it needs re-tensioning (I think after 500 miles).

Sorting out the auxiliary shaft alignment is a pretty easy job, hopefully you will have your motor car running again by this eve.

Good fortune,

Alan

PS. I've circled what looks like the auxiliary shaft timing mark in your photo. With the RB I couldn't see the mark - I could just feel it with the tip of a sharp screwdriver. This mark seems to be in the right place, if so the sprocket seems to be several teeth out of synchronisation in the anti-clockwise direction -



...which supports Bugjam's idea that it may have slipped on start up to cause the poor running.

[Juular]

At TDC it should be at around the 3 o'clock position.

My 88 has a plastic case behind that is clearer to see.

[Othen]

Originally Posted by Juular

At TDC it should be at around the 3 o'clock position.

My 88 has a plastic case behind that is clearer to see.

Actually, although yours is a later engine that is quite helpful.

The B21a has a pressed steel case and the mark is really difficult to discern, I've marked it with a bit of Tipex in this photo (from the RB):



... it is just a small punch mark. The important thing is that the mark is a bit further clockwise than the blue circle I'd put on the photo above, more like here in Bob's engine:



... as you say, at the 3 o'clock position. If that is correct then it does mean the sprocket is about 4 teeth, or retarded by about 36 degrees, from where it should be (which corresponds to 15 BTDC) - no wonder the distributor has run out of adjustment. It would seem likely that the belt has jumped a few teeth, I doubt that it could have run like that. Perhaps the tensioner was too slack?

Alan

[Juular]

It might improve visibility to take a small toothbrush sized wire brush to the casing. The mark should stand out much clearer when it's not filled with debris.

[Bugjam1999]

I'm not entirely convinced that the B21 engines had a mark on the metal timing back plate for that pulley, yes it's there for the later engines with a plastic back plate, but I had a 1978 a while back and I'm pretty sure it didn't have anything for the aux shaft - and I cleaned the whole area looking for it with a wire brush etc.

Bear in mind everything Volvo does in terms of marks etc. is pretty clear, feeling around for a minor bump on a pressed steel plate... just doesn't feel like a mark that Volvo would have designed/put in place.

The distributor timing can also be checked by looking under the distributor cap.

Remove the distributor cap, rotor and the dust shield under the rotor. Replace the rotor and with the engine at TDC the rotor should point at a distinct line on the distributor edge.

https://forums.turbobricks.com/showthread.php?t=356215

There's a photo at the top of this thread of what you're looking for (it's a different distributor in the thread to the one you have, but the line you're looking for is the same)

Cheers

[Bob 1967]

That part of the elimination process is complete , timing set .

On to carb. Started by removing the Filter housing (big round one )and then.........
The idle screw is missing. It must have worked itself loose .
OMG.
If I get a replacement it will have a plug over it , so I don't get a repeat performance.

Well at least everything got a good clean. Tensioner is fine as is its bearing.
I will update as soon as I find a replacement.
Bob.

[Othen]

Originally Posted by Bugjam1999

I'm not entirely convinced that the B21 engines had a mark on the metal timing back plate for that pulley, yes it's there for the later engines with a plastic back plate, but I had a 1978 a while back and I'm pretty sure it didn't have anything for the aux shaft - and I cleaned the whole area looking for it with a wire brush etc.

Bear in mind everything Volvo does in terms of marks etc. is pretty clear, feeling around for a minor bump on a pressed steel plate... just doesn't feel like a mark that Volvo would have designed/put in place.

The distributor timing can also be checked by looking under the distributor cap.

Remove the distributor cap, rotor and the dust shield under the rotor. Replace the rotor and with the engine at TDC the rotor should point at a distinct line on the distributor edge.

https://forums.turbobricks.com/showthread.php?t=356215

There's a photo at the top of this thread of what you're looking for (it's a different distributor in the thread to the one you have, but the line you're looking for is the same)

Cheers

Here is the photo from the BofH - there is clearly supposed to be a mark but it isn't very significant:



... I'd say that is just what I found with the RB, a feint mark that I could only find with a sharp screwdriver.

Alan

[Bob 1967]

Volvo Part 1269035
Actuator, Idle Control.

[Othen]

Originally Posted by Bob 1967

That part of the elimination process is complete , timing set .

On to carb. Started by removing the Filter housing (big round one )and then.........
The idle screw is missing. It must have worked itself loose .
OMG.
If I get a replacement it will have a plug over it , so I don't get a repeat performance.

Well at least everything got a good clean. Tensioner is fine as is its bearing.
I will update as soon as I find a replacement.
Bob.

Nooooooooooooooooooooooooooo! It is good news that the timing is sorted out, did realigning the auxiliary sprocket sort the problem?

By the idle screw do you mean this one?



It is too late now, but I had a problem with that screw slowly coming undone (so the idle speed would gradually increase over a period of a few months). I solved it with a tiny drop of thread lock - just enough to give it some resistance. I have no idea where you will find another screw like that - maybe put something in the wanted section of this forum?

Alan

[Bob 1967]

On timing marks .....