heliflyer

Hi Guys,
Looking for some thoughts from the engine gurus here.
i have a puzzling intermittent issue with my 1986 euro auto.

Just occasionally, when first started, the car emits white smoke from the exhaust - usually for no longer than a few seconds, although I have had it happen once for about 2 minutes. It does not do this every time the car is started (have not seen white smoke for over a week now).
Additionally, sometimes, when pulling up at a junction afer a spirited drive, there is again a short puff of white smoke lasting maybe 4 or 5 seconds.
I am getting the low coolant warning anywhere between 2 and 5 months after topping it up - no signs of coolant leaks anywhere.
The car is used as a daily driver, but generally only gets 2 10 mile drives each day (to work and back) with the occasional longer weekend drive.

My first thoughts are head gasket, but I would be surprised if this caused an intermittent problem - I would have thought that once the gasket started leaking the problem would be there all the time.

First plan of action is to test the coolant with a block test kit and then go from there, but I would appreciate any other thoughts.
thanks

GlenL

It sounds like you've got a handle on this. The intermittent smoke is odd but losing coolant along with white tailpipe smoke on start-up signals a head gasket leak.

A good test is to pull the plugs and probe inside, or just crank the engine in which case the coolant will often fly out of the holes. Test after getting the car good and hot and letting it sit for two hours. That way any coolant will be in the bores and not have drained into the oil.

fraggle

How are temps?

Do a compression test, too.

If your motor is in good shape the cylinder to cylinder variance will be very tight, probably within 3 or 5 psi.

Watch for side to side differences or trends.

When mine went I had similar symptoms. Lost coolant, not much or very intermittant smoke.
Good luck!

heliflyer

Fraggle
Temps are fine - no sign at all of any overheating. I'll do a compression check also.

Glen
Thanks for that suggestion. There is no sign of any coolant in the oil at the moment, although I do often get the "milkshake" in the oil filler. This disappears after a long drive however so I have put this down to condensation not clearing due to the frequent short runs that the car does.

Thanks

Mrmerlin

pull the plugs and look for either very clean tips or rust on the tips.
Either will indicate a coolant leak into that cylinder.
How old is the heater control valve and the coolant bottle cap, either one might cause coolant to be lost., Also check the inlet side tank of the radiator for leaks and then also check the inside of the V for crusty deposits along the head gasket.
10 miles a day each way may not be enough to get the engine up to temp I suggest that you double that

mark kibort

since the coolent might be entering the cylinders after you shut it off, while the water jacket is under 1 bar pressure, you might have a pin hole leak that allows water to enter the cylinder until the engine cools down. you start up, it blows out, white smoke, etc. no problem any other time? If that is the case, I would add a can /bottle of Barr's stop leak and keep an eye on it. If this is what is happening, pull all the plugs as was mentioned after it cools down from a run, and water should shoot out the cylinders when you turn it over.
If the plugs are ok looking. (not REALLY CLEAN) then you probably are ok

heliflyer

OK, checked the coolant with a block test kit and it indicates combustion gases in the coolant. Car did again produce white smoke on cold start when doing the test.
Pulled the plugs, and all looked identical - a nice even pale brown color with none looking obviously cleaner than the others, although number 3 cyl did have a slight yellowing deposit in the ground electrode.
No signs of any coolant being expelled from any cylinder when motor spun with plugs out.
Did a compression check with the following results:
Cyl Psi
1 184
2 165
3 157
4 167
5 170
6 170
7 162
8 170

Cylinders 1 and 3 have the obvious discrepancies so test repeated with the same results.
I am going to try a can of Bars Leaks and see if that helps for now. Any other thoughts appreciated.

laufenOutLoud

Yikes, that's some big variances. I think that confirms the HG diagnosis. I'm not sure about canned HG fixes when it's anything more than tiny bubbles in the coolant. I've only tried twice (and not on a 928) and I'm one for two.

GlenL

I only put stop leak in cars I have written off otherwise. It'll clog the radiator and the heater core. No two ways about that.

It sounds like you did the right tests and those were inconclusive. Your description suggested an intermittant leak into the cylinders, and a small one at that. This leaves you with two options:

* Keep driving it as-is until the problem becomes obvious

* Do the head gaskets now without proof but with some confidence that there's a problem.

I'm not too concerned about those compression numbers. It's a long way fromm 157 to 184 but those are fliers from a 168 average and tolerable from that level.

heliflyer

Yes, cylinders 1 & 3 seem to be out but the others are all pretty close.

Other than the smoke on some start ups the car drives fine - no signs of overheating at all and no power loss.

I don't like the Bars leak option either but have found this product - Steel seal - in the UK. http://www.steelseal.co.uk/

It's apparently a US product so perhaps someone may have heard of it and know if it works as they claim??

They claim it doesn't contain any blocking fibres so I will give it a go. If it doesn't work then I guess I will have to pull the engine and do the heads.

fraggle

Start planning the pull. You've got a couple months, I'd guess, before it becomes terminal.

SwayBar

According to your symptoms, you do have a head gasket issue. It doesn't matter at this point which side it's on (..I'd say passenger), as you should go ahead and change both.

Hmm, I just noticed you have an 86 which will require pulling the engine to remove the heads; now that is a lot of work.

Also, once the heads are off, depending upon mileage, you should consider new valve guides and seals.