900 B230FK head - waterways sealed - why??

[eeedelli]

Originally Posted by 230ina245

I would be slightly worried about the amount of gasket clamping area that is left between the corroded area and first bolt hole (bottom left on first picture).

Yes I see what you mean. It is quite close isn't it! Having said that, I'd have hoped that the machine shop would have suggested it if they'd thought it was necessary. Unfortunately, I don't know how much was skimmed already in this operation. There again, It's not a bolt hole carrying any fluids (unlike the one that brings the oil up to the head) so as long as there's enough to spread the load all around it while still digging into the narrow bit, I would imagine that it will be ok. I suppose the worst thing would be if it did creep, it would end up filling the bolt hole with coolant, which would make getting the head off in future rather tricky if it corroded the bolt into the block.

Originally Posted by 230ina245

You mentioned overheating in your first post - was this because the head gasket had blown and where did it let go?

Ah - when I said that I "caught it *before* it overheated", I probably should have made clear that it didn't actually overheat. I'd only done a 15-20 minute journey on a fast road so when I pulled in and stopped, that was the first time I realised there was something wrong as it was running on 3, so I switched off and quickly investigated. The coolant level had only just reached the bottom of the expansion tank and the gauge was showing normal.

When the machine shop rang the first time, the bloke I spoke to reckoned that it was barely worth skimming it as he reckoned it was just about within tolerance so I was slightly surprised when I went to pick it up that it had been skimmed.

What I did notice during dismantling, however, was that there were signs of water staining below the block-head interface around cyl 2 (which is the one that steam cleaned itself), hidden out of sight behind the exhaust manifold. I wonder whether it was just the head bolts that weren't quite up to torque (though they were difficult enough to get off).

[Laird Scooby]

Originally Posted by eeedelli

Yes I see what you mean. It is quite close isn't it! Having said that, I'd have hoped that the machine shop would have suggested it if they'd thought it was necessary. Unfortunately, I don't know how much was skimmed already in this operation. There again, It's not a bolt hole carrying any fluids (unlike the one that brings the oil up to the head) so as long as there's enough to spread the load all around it while still digging into the narrow bit, I would imagine that it will be ok. I suppose the worst thing would be if it did creep, it would end up filling the bolt hole with coolant, which would make getting the head off in future rather tricky if it corroded the bolt into the block.



Ah - when I said that I "caught it *before* it overheated", I probably should have made clear that it didn't actually overheat. I'd only done a 15-20 minute journey on a fast road so when I pulled in and stopped, that was the first time I realised there was something wrong as it was running on 3, so I switched off and quickly investigated. The coolant level had only just reached the bottom of the expansion tank and the gauge was showing normal.

When the machine shop rang the first time, the bloke I spoke to reckoned that it was barely worth skimming it as he reckoned it was just about within tolerance so I was slightly surprised when I went to pick it up that it had been skimmed.

What I did notice during dismantling, however, was that there were signs of water staining below the block-head interface around cyl 2 (which is the one that steam cleaned itself), hidden out of sight behind the exhaust manifold. I wonder whether it was just the head bolts that weren't quite up to torque (though they were difficult enough to get off).

Sadly it doesn't take much to kill a head gasket and/or warp the head. The damage may in fact have been done on a previous journey, especially if your thermostat was/is weak as it prevents even heating of the head and allows "hot-spots" to develop. A weak 'stat could also cause the head to warp as the engine cools because it's not holding the heat evenly inside the head. Could also be worth investigating the block if you have further troubles.

[eeedelli]

Originally Posted by Laird Scooby

Sadly it doesn't take much to kill a head gasket and/or warp the head. The damage may in fact have been done on a previous journey, especially if your thermostat was/is weak as it prevents even heating of the head and allows "hot-spots" to develop. A weak 'stat could also cause the head to warp as the engine cools because it's not holding the heat evenly inside the head. Could also be worth investigating the block if you have further troubles.

Yes - good point. Having said that, I did put a new thermostat in it when I went right through replacing loads of stuff on it (including all new cooling hoses, water pump, valve etc. just after I'd got it, 5 years ago) and it's only done about 2-3000 since then as the 2nd car, with the temp gauge rock steady in the normal position, so I don't think the thermostat was the issue on this occasion.

Mind you, on this more significant dismantling, I found that some twit had obviously had it apart before and hadn't put the thick forged steel domed washers on the exhaust studs that are there to provide a little resiliance when the manifold gets really hot and the consequence was that I found a snapped exhaust stud. If the same lack of attention to detail was applied previously to the head then there's no telling what else might have been wrong that caused this failure!

I'll check the block again for 'true'. I did do a check a few weeks ago when I took the head off but it seemed almost a trivial amount. (Can't quite remember what it was now but it was less than the smallest feeler gauge in my set, if I recall correctly, so I didn't think too much about that.)

[Laird Scooby]

Originally Posted by eeedelli

Yes - good point. Having said that, I did put a new thermostat in it when I went right through replacing loads of stuff on it (including all new cooling hoses, water pump, valve etc. just after I'd got it, 5 years ago) and it's only done about 2-3000 since then as the 2nd car, with the temp gauge rock steady in the normal position, so I don't think the thermostat was the issue on this occasion.

Mind you, on this more significant dismantling, I found that some twit had obviously had it apart before and hadn't put the thick forged steel domed washers on the exhaust studs that are there to provide a little resiliance when the manifold gets really hot and the consequence was that I found a snapped exhaust stud. If the same lack of attention to detail was applied previously to the head then there's no telling what else might have been wrong that caused this failure!

I'll check the block again for 'true'. I did do a check a few weeks ago when I took the head off but it seemed almost a trivial amount. (Can't quite remember what it was now but it was less than the smallest feeler gauge in my set, if I recall correctly, so I didn't think too much about that.)

Despite popular belief and apparent evidence, thermostats don't actually last that long before they get weak. A long warm up (more than about 5 minutes max) indicates a weak 'stat and some cars have other indicators as well, for example on my other car, it won't engage torque converter lock-up unless the coolant is 74C or higher.

The standard UK 'stat is only 78C so a weak 'stat usually shows up as a gearbox problem!

I now run an 82C 'stat in it (still trying to find the Nordic 88C 'stat for it) and change it every other coolant change. I change the coolant on both every 2 years with a basic reverse flush every time and add the flushing agent every other flush when i also renew the 'stat.
Even when the 'stat goes weak in it (<74C coolant temp) the gauge still sits where it should so the problem wasn't immediately apparent.

I do, and have done the same procedure on the Volvos i've owned (and every other car) and it's always repaid the favour by giving me a good heater, fast warm up and no problems with coolant temperature related faults.

I also don't do many miles although slightly more than you, i've done about 12k in 4 years in the Volvo but probably only about 1200 in the Rover. That said, the Volvo is coming up for its third coolant change in my ownership (it was nasty when i first got it, 90% water! ) so had a serious flush/backflush, a new 'stat and a new expansion tank cap. The 'stat is now getting weak as even on a warm day, the temp gauge has only just started to move after ~1/2 mile or about 2-3 minutes and doesn't quite get to properly warm unless i go further afield. When the 'stat was new, at the same point on a cold (-3C) day it was already past the C mark on the temp gauge. Also by the time i got to where i was going on my shortest run (walkies area for the pooch) it was up to normal temperature. Now it's barely halfway there on a warm day.

As i'm sure you've worked out from this, a weal 'stat can cause problems, even when it's seemingly ok according to the gauge.

You've hit the nail on the head with your comments about previous attention to detail! On my last 740, the head gasket and head were meant to have been done about 9 months before i bought it with very few miles in between. I started getting a misfire and on a pure hunch, checked the head bolts for tightness. They were all below the Stage 1 tightening (44lb.ft), some looser than 15lb.ft so not much more than finger tight!
Tightened as they should be and the misfire disappeared but it started to run strangely as if the timing was wandering all over the place like a mad womans breakfast. Sure enough, it was so i checked the timing belt tension. It barely had any so i bought a new belt and fitted it, correctly tensioned and the wandering timing disappeared.

On this 760 that i've had 4 years, i've found multiple bodges like a pile of washers on the fronts of each space ship bush to get it through the MoT, the A/C evaporator was removed because it was allegedly blocked (the actual fault was dry joints on the PCB that operates the vacuum valves that operate the air flaps and heater valve), the engine oil cooler was removed because it was leaking PAS fluid to name just three.
New spaceship bushes, re-centre the rack and correct the wheel alignment and the PAS leak from the oil filter immediately disappeared - the rack was off-centre so the PAS was working even in a straight line so the PAS fluid was boiling and coming out of the breather hole in the reservoir (integral reservoir with the pump on mine), repaired the A/C PCB and have fitted a replacement evaporator, still needs regassing though and i eventually found an OE oil cooler and will have to modify the hollow nut that secures it as the OE one (called a nipple by Volvo) is NLA but that should be the last of the previous owners bodges/misguided repairs sorted i hope!

Thing is, you can't legislate (or sometimes even imagine) the stupidity of people who have previously worked on cars. It might work but it ain't right but they think it's perfect. As such you have to assume the worst and regard any improvement on that as a bonus. Chances are if the HG was previously done on yours it wasn't tightened correctly and then not retightened at 600 miles and the timing belt probably wasn't retensioned at the same time.

The turbo would have masked a lot of the symptoms (lack of power for a start) so in many respects you probably caught the HG in time but if the machine shop skimmed the head, it almost certainly needed it.

Some people advocate using a sealant on a new head gasket, normally i'd suggest not but given that the top of your block doesn't look that great and the previous history is unknown and the head itself is still in question, i think it may be a good idea this time. I think the usual "goo of choice" for a sealant is Blue Hylomar but maybe someone who has used a sealant in the past will suggest something better.

Also make sure the head bolts whizz freely in and out like free whizzy things before you fit the head as well, a light smear of oil on the threads when you fit them to help lube them as they go in and you should be ok. There are two types of head bolts on the red block, some are stretch, others not. If you're not sure which you have, renew them. Yes it's an additional cost but a small insurance fee to pay to know they're ok. Certainly cheaper than doing the whole job again, perhaps with additional repairs/parts needed if it goes again because the head bolts shouldn't have been re-used.

[eeedelli]

I'm surprised to hear of 78C, as I've never found anything lower than 82/83C for summer running. The one I put in was an 88, which I'd always thought was the normal one (87/88C depending on make). I think I've seen a 92C mentioned for cold climates but I've never encountered one. Yes - I've noticed I can't get into lockup until it's warmed up, too.

My 740 has always taken a while to warm up whereas this 940 seems remarkably fast. I'd always put that down to being auto and turbo, with both ATF and engine oil coolers dumping heat into the cooling system. One thing I do know, however, is the air con has never worked since I had it. I know that the rad fan is controlled from a pressure stat in the aircon so that won't help in hot weather if there's no pressure there but there is an ECU temp sensor that brings the fan on occasionally when it's been standing for many minutes but, again, the gauge doesn't seem to move above normal before that's happened so it seems to be catching things in plenty of time. I'd not bothered about the aircon in view of that. I'm not sure whether there's any pressure in the system as pressing the aircon button doesn't even engage the pump so I wasn't sure whether it was failing to engage as a safety measure when there's no pressure or whether it's something else. As I say, I hadn't bothered as the fan seemed to be working but maybe that's only a 'last resort'.

Your timing story reminded me of when I put this one in to have the rear crank seal replaced at an auto transmission place. They managed to put the flywheel back on 45 degrees out! How on earth it was even running, I shall never know but suffice to say the journey home was 'interesting' and once I'd realised what they'd done and proved it with a strobe light, they had to come and pick it up with a flat-bed to take it back to rectify it. I wasn't going to make another journey like that - stalling all over the place in traffic!

Yes I was wondering about gasket sealant. The machine shop recommended leaving it dry. I was hoping to get on with it today but I don't think I've got any Hylomar. (I know I used to have some about 20 years ago but goodness knows where it is and I expect it will be well past it by now!)

I'd already taken the precaution of cleaning and chasing the threads for the head bolts. Everywhere I look (online, in Haynes etc), they say to replace them if they're longer than 55.5mm but that's only just over 2" and they're already miles longer than that. They all seem to be about 155mm so I assume it's a misprint that's just got propagated around. I'll check them again and measure the length. I also need to take some measurements to check that the skimmed head won't result in the bolts bottoming out.

Anyway, in the meantime, I need to do an oil and filter change on the 740, amongst other things, to keep that one on the road if I can get to it - it's all go!

[Laird Scooby]

Originally Posted by eeedelli

I'm surprised to hear of 78C, as I've never found anything lower than 82/83C for summer running. The one I put in was an 88, which I'd always thought was the normal one (87/88C depending on make). I think I've seen a 92C mentioned for cold climates but I've never encountered one. Yes - I've noticed I can't get into lockup until it's warmed up, too.

My 740 has always taken a while to warm up whereas this 940 seems remarkably fast. I'd always put that down to being auto and turbo, with both ATF and engine oil coolers dumping heat into the cooling system. One thing I do know, however, is the air con has never worked since I had it. I know that the rad fan is controlled from a pressure stat in the aircon so that won't help in hot weather if there's no pressure there but there is an ECU temp sensor that brings the fan on occasionally when it's been standing for many minutes but, again, the gauge doesn't seem to move above normal before that's happened so it seems to be catching things in plenty of time. I'd not bothered about the aircon in view of that. I'm not sure whether there's any pressure in the system as pressing the aircon button doesn't even engage the pump so I wasn't sure whether it was failing to engage as a safety measure when there's no pressure or whether it's something else. As I say, I hadn't bothered as the fan seemed to be working but maybe that's only a 'last resort'.

Your timing story reminded me of when I put this one in to have the rear crank seal replaced at an auto transmission place. They managed to put the flywheel back on 45 degrees out! How on earth it was even running, I shall never know but suffice to say the journey home was 'interesting' and once I'd realised what they'd done and proved it with a strobe light, they had to come and pick it up with a flat-bed to take it back to rectify it. I wasn't going to make another journey like that - stalling all over the place in traffic!

Yes I was wondering about gasket sealant. The machine shop recommended leaving it dry. I was hoping to get on with it today but I don't think I've got any Hylomar. (I know I used to have some about 20 years ago but goodness knows where it is and I expect it will be well past it by now!)

I'd already taken the precaution of cleaning and chasing the threads for the head bolts. Everywhere I look (online, in Haynes etc), they say to replace them if they're longer than 55.5mm but that's only just over 2" and they're already miles longer than that. They all seem to be about 155mm so I assume it's a misprint that's just got propagated around. I'll check them again and measure the length. I also need to take some measurements to check that the skimmed head won't result in the bolts bottoming out.

Anyway, in the meantime, I need to do an oil and filter change on the 740, amongst other things, to keep that one on the road if I can get to it - it's all go!

That's Honda for you, fit a 78C 'stat for the UK market! The Nordic one is 88C but they're thin on the ground, they occasionally come up for the 216/416/Civic/Concerto on fleabay but sell really quickly - can't think why!

That's a thermostatic switch in the rad for the secondary A/C fan, brings the secondary fan on if the temerpature in the rad goes above a certain level and the A/C system will also bring the secondary fan on as you'll find out if you get it regassed which is probably all that's wrong with it. With winter coming would be a good idea though!

Head bolts, i'd suggest the real figure is probably 155.5mm but if you wind one into the block as far as it'll go and measure what's left out then measure the head, that should give you an idea if they'll bottom out or not.

Usually the bolts that need to be renewed are the ones with a "waisted" section that stretches.

[TonyS9]

I use Evans waterless in my B230FT in a 360 I use on the track. Its not as conductive as water and the 360 cooling is a bit marginal, however I seem to have got it within a reasonable spec now without having to go to the Chinese poor fitting aluminium radiator. Havn't seen it get above half way for some time now, but it might do on a hot day on the track. Never went into the red.

I did convert back to water + oats at one point and it ran cooler but the resevoir was close to bursting after a session, and there was some boiling and pressure relief going on after stopping. The 360 system is not designed to the same pressure as the 940 turbo, with double the pressure on the relief valve in the cap, so I went back to waterless.

The main benefit is no corrosion and little pressure, but it will be expensive if you have a leak.