V12 smoking habit. Any ideas?

[Marcusj1000]

Hello everyone.

After some upper engine work I have reassembled everything (including newly rebuilt carbs) and I have a fair amount of white smoke coming from the exhaust.

I have used a small mirror to inspect and the smoke is condensing as water on the mirror. Everything looks fine on the compression test and although it is running rather rich it seems to be running ok. There's no evidence of water in the oil and I have replaced the valve stem seals, I can't work out what's happening! In the past I would see more smoke than expected while the car is cold but it's always cleared after 3 or 4 miles.

I have removed some oil from the sump as I noticed the crankcase breather pipe had some drops of oil in it. When running with the breather disconnected there is a faint whitish smoke that again I think is water. Is this normal? Is there another way to test this that anyone knows of?

Could a head gasket be at fault? I very much hope not as I'm aiming to get the car ready for my wedding in 4 weeks!! Where else could this moisture come from?

Unfortunately the MOT has expired so I can't do a proper road test until I'm on my way to the test station (Friday, fingers crossed).

Any help or ideas are welcome.

As usual, thanks in advance.

Marcus.

[MarkE]

Marcus, it does sound like head gasket. Alternatively, if you took the heads off, did you turn the engine over (by hand) with them off? If so, did you clamp the liners in position? If not it's possible that one or more liner seals could have been broken, which would allow water into the crankcase and / or combustion chamber.

Have a good look for oil in the water or water in the oil.

But I do hope it is something more simple!!

[PeterCrespin]

How many miles did you go? These are large engines with twin exhausts and a large tilted silencer at the cold end - all conditions that predispose to condensation. As it's a rebuilt engine I don't suppose you drove it hard. If it's a leak, your coolant level will keep falling rather than level off. One or more plugs would also be steamed clean. My bet is there's nothing wrong and if there is all doubt will be removed by other symptoms that have been mentioned. You could book it into a Jaguar specialist place of repair 50 miles or so awayand drive in that direction legally and then turn back after thirty miles having changed your mind. So long as you have a bona fide booking you are allowed the trip to and from the MOT place or a place of repair to prepare it. It's a chance to do a bit of a shakedown anyhow. Remember too that a V12 can stop steaming after warm-up and then start again in slow traffic, depending on weather conditions.

I'd check the head torque and carry on to either provoke a clear problem or dispel your concerns. The actions and outcomes will be the same either way but at least you will clarify the situation. Did you check the liners were a few thou above the block face?

Pete

[Marcusj1000]

Hello again.

The engine has done about 600 miles since I replaced one of the head gaskets (last summer) and since then I have replaced the stem seals and valve springs. I did this with the heads in situ. I can?t remember turning the engine at all with the head off, I was hoping that the OK compression test results would have ruled out head gasket trouble but I guess that only counts for the cylinders and not any of the oil/water channels or liner seals.

There is no sign at all of water and oil mixing......... yet. How quickly would these signs become apparent? I guess that depends on the severity of the problem.

All my plugs are dry and sooty (as she has only been idling and has been running very rich) so no "steam cleaning" going on there that I can see.

I will make sure she has a good run on the way to/from the MOT station, I will get the MOT done before I start stripping her down so I can do some test runs when reassembling.

As much as I don?t want to admit it, it does sound like a head gasket failure between oil and water channels (are they in close proximity on these engines? I can?t remember) or a liner seal. Is there any way of testing the liner seals without dismantling?

I have also had it recommended to me that a good test is to replace the rad cap with a tyre valve and pump up the pressure in the coolant system, then to leave and monitor the pressure drop. Has anyone tried this?

I really am open to all suggestions and opinions. If I start stripping the car of its heads now then there?s no chance of making it in time for the wedding.

Thanks again everyone.

[MarkE]

Marcus
The old V12 is a pretty forgiving engine, and my experience is that it takes a lot for a head gasket to fail. This was the state my gasket was in when I stripped my S3 engine, which hadn't had any antifreeze for 30 years (warm / dry climate car):



And the engine was running perfectly!

The liner seal is quite an easy thing to disturb, especially in an engine that has never been apart. But if you didn't turn the engine over, chances are that would be OK.

I think that Pete makes some very good points, and before you start to strip anything down, run the engine up to temperature, and when the fans start up, keep running it for another 20 minutes or so, to make sure that all moisture has been driven out from the exhaust system. When I do this I usually increase the tickover speed to 1500 - 1800 rpm just so that the water pump is doing something.

When my liner seal went in an XJS, it was as a result of my replacing a head gasket, but I did turn the engine over without heads and without clamps. The white vapour coming out of the exhaust was like the engine running on a cold day, but it kept on coming when the engine had been running for a long time, and eventually caused the engine to run on 10 cylinders, whilst belching out 'steam'. The XJS also runs two parallel exhaust systems, and only one side was steaming....a bit more tricky to determine on the S3

I didn't find any water or oil contamination, which I don't really understand, but the water level did continue to drop.

[Marcusj1000]

Oh dear.

I'm now becoming more and more convinced that I have a liner seal issue. I cant remember turning the engine over while the head was off but it is possible as it was a long term job. I also cant be sure on the previous owners handy work, the car hadn't been run for some years and had the heads off during that time.

I have had the car ticking over for a fair time, well up to temperature.

The water level has dropped too.

All I can do is take the car to the MOT station and pray she passes. If I'm still smoking when I get back home then I think I'll remove the exhaust balance pipe and see if its obviously coming from one bank.

After that, I will probably be quietly sobbing to myself. If you see a forum post from me on Friday asking about the best way to change a liner seal then you'll know how it went.

I wonder how many late nights in the garage it will take to change a bank of liner seals.............??

Thanks for your responses, I'll remain optimistic and keep my fingers crossed.

[MarekH]

Dear Marcus,

It's not unusual to find that the first couple of times that the car is started that water makes its way past the head gasket, but after a couple of heat cycles and retorqueing the head nuts, it settles down and no more water is lost.

Mine clearly had steam escaping a haze above the heads the first two times it went past 2500rpm, but nothing at all since then. Another friend who rebuilt his heads had water gushing out the first time he started it up and nothing untoward after that.

It isn't certain that the absence of liner clamps will lead to problems - if the liners have been stuck into the block for 40 years, then it'll usually take quite a lot of force to shift them loose. The fun might start if one of them has been replaced and is not replaced at the same height as the others.

As Pete said, there will be a lot of condensation in the exhaust at startup.

kind regards
Marek

[vee12eman]

Hi Marcus,

Pressure testing the system cold is possible and useful. I have just done exactly this, albeit using a properly designed tool, but dismantling the tool revealed a Schrader valve, and a pump virtually identical to a bicycle pump. Adapting a valve cap seems perfectly possible and as I borrowed the tool this was to be my next project. You will have to work out a method of blocking off the header tank overflow port integral with the filler neck (where the cap is fitted). The tool I borrowed did this with a rubber block, perhaps I can take some pictures before I return the tool. You could probably remove the spark plugs from the cylinders and see if water had flowed into the bores under the pressure - don't overpressurise the system, which is designed for around 13 psi.

Regards,

Simon

[PeterCrespin]

Hello again.

The engine has done about 600 miles since I replaced one of the head gaskets ...
All my plugs are dry and sooty (as she has only been idling and has been running very rich'.

I'm confused. Since when does an engine idle for 600 miles after a repair? If you are questioning condensation vs. headgasket steam from a V12 at idle, the first thing to do is take it out and drive it properly so the exhaust warms up.

If you have done 600 miles successfully why would you think it suddenly failed if you haven't touched the headgasket or potentially moved a liner 600 miles ago last year? Prolonged idle is enough to drop the coolant level if it was over-filled. Provided you can still see (with a mirror) or see coolant on a home made header tank dip stick you should leave as-is and drive the thing hard keeping an eye on the gauge. When cool see if there's a bit still in the tank. Then warm it up with the cap off to check the temp against your gauge with a cooking thermometer and to see that the coolant expands into the tank. Don't overdo it with the cap off because eventually it might bubble over but if it comes up to 60-70C with coolant expanding into the tank and your gauge reading more or less correctly you can put the cap on and drive with confidence, whilst keeping an eye on things until you and/or the car settle into a normal pattern.

Pete

[Marcusj1000]

Hi Pete,

Thanks for the response, apologies maybe I?ve not been clear enough, here?s a timeline of the car

Circa 1998 previous owner: Cam chain broken, valves meet pistons
1998 ? 2011 previous owner: Most engine work completed over this period by local mechanic then never finished or run.

2011: I purchase car and commence a recommissioning job, this includes removal of LHS head to check suspected valve seat problem and to replace some questionable valves. Engine was not turned over but liners were not secured either?.as far as I can remember.

2012: Amongst other jobs the car is running again and passes MOT. There?s more smoke than I would prefer when the car is cold but that stops after about 3 or 4 miles. Car seems fairly reliable apart from noisy top end (incorrectly shimmed cam followers<by me!!!>). 600 miles varied driving completed during the summer.

NOV 2012-now: Stripdown of top end to replace the stem seals (stupidly didn?t do this when the head was initially off) Heads kept on the car for all this work. Discovered several broken valve springs ? replaced all with new. Rebuilt top end, retimed, rebuilt carbs (still too rich I think). Now even more smoke than before ? condensing on mirror.


I will be trying to lean off the carbs before Fridays run to the MOT station and I will do as many miles as is sensible on the way there/back. Over the weekend I will run the car up to temperature and also drain all the oil (when its cooled a little) I?ll have a very close look at the condition of the oil. I am also considering pressurising the coolant system and looking for leaks.

After this is all done, I will consider my next move.

Once again, all suggestions are still very welcome.

Marcus.

[PeterCrespin]

Sorry, that's more or less what I thought you'd said. It still makes little to no sense to be wondering about a head gasket or liner, given the car ran fine for 600 miles with condensation clearing after 3-4 miles. You've done nothing, nada, zip, to change the situation since, so it will surely be the same when you treat it the same.

Unless you've driven it longer than 4-5 miles since the spring/seal work and it is still steaming heavily, I don't see any issue.

Pet

[Marcusj1000]

Hi guys.

Just thought I'd let you know what progress I've had as promised. Great news.... She passed her MOT. Nothing but and advisory on a split track rod end boot. All sorted and I've been able to actually drive her again. A few silly teething problems, the main one being that I forgot to replace the timing chain tensioner bung, throwing oil everywhere! My main concern has been the smoke / steam. A good run out made a huge difference and it was only really smoking after slow driving, then a good blast seemed to clear things. Controversially I decided to use rad weld. I have a new (ish) rad so I'm confident with the cooling system and this (along with fresh oil) has improved things further. I'm still smoking a fair bit, it's intermittent and difficult to say if it's oil or water that I'm burning but for now I'm going to get as many miles on her as I can afford, I'll use her for the wedding in 3 weeks, then over time work out what really needs doing.

I still have a fundamental question regarding the vacuum pipes from the carbs. I've looked at the schematics as advised earlier and I still have questions. I'm informed that the pipe on the LHS rear carb underside is for the dizzy vacuum, however I can see evidence of fuel coming from this pipe, mixing fuel and distributors doesn't seem right to me so I've bunged it for now. Is that a sign that I'm going to the wrong place or that I have the carbs poorly set up? The other pipes from what i think is the bypass valves are currently routed to the corresponding inlet manifold. Is that correct? I've searched and searched but can't find the answer. All is looking good, I've even had time to polis her and drive to the pub for a shandy in the sun. It's all beginning to become worthwhile now! I'm a happy etype owner!

Thanks all for your help.

Marcus.