Mongo

Hey guys I'm completely stumped as to where to trace the damn smoke coming from this car. There's enough to seep through the vents, under the dash, through the console and to come out of the side of the car! It runs fine, better than ever! But the smoke is pissing me off. When the hood is up, it looks like there's smoke coming from behind the airbox and intake manifold. I tried my very best to clean the manifold but I'm going wacko here as to how much smoke comes inside the car sitting at a stoplight. Kinda embarrassing actually seeing that my car is 'hotboxing' itself.



Anyone have any similar situations, or found a solution to fix this???

Kevin in Atlanta

What does the smoke smell like?

Ketchmi

Odds are that it is the rear cam plugs. They are a real bit*h to change and they drip directly on the exhaust when they are bad.

Mongo

it smells like oil and I bet you're absolutely right Ketchmi. Do you have to remove the camshafts???

Mongo

oh i also might add that it smokes at a full stop after accelerating and going up hill or parked on an incline

Tails

Andy,
As previously stated the oil maybe coming form the rear cam plugs or it maybe coming from the camshaft covers. I have a small leak from the LHS camshaft cover gasket, very minor but when the oil drops onto the exhaust manifold and/or exhaust pipe you can smell it in the cabin. If you are getting smoke then you have more than a small leak.

I would suggest that you place the car on a lift or protable ramps, hop under the car with a strong flashlight and inspect the lower gasket of the cam covers for leaks as well as the rear cam plugs. If you cannot see where it is leaking then I would say you need to clean around these areas for a good inspection until you can firmly locate the source of the leak/s.

Once located we can advise you on the best repair method. I would not suggest that you go in tearing out bits and pieces hoping that it will solve the leak/s.

I recently cleaned this area with a high pressure water pump jet to locate my leak and it is so minior that I'm willing to live with it for the present.

Tails 1990 928 S4. Auto

Mongo

from what I saw tails, it looks like the passenger valve cover and driver side valve covers are both leaking! There's sludge around those areas too indicating a long time leak or maybe a previous fix but the age of the gaskets once again started to leak again. the plugs looked wet on passenger side

This is not good

worf928

That's one way to look at it.

The other way is: time to get everything powder coated.

Mongo

ok what needs to come off then if I need to do end plugs? I know the airbox, that's the easy part. I'm gonna check PET and see what seals I will need to do the plugs. I also have to do gaskets for valve covers. The powdercoating job is gonna have to wait unfortunately.

david928

The same thing has happened to me. A couple of time after stopping, oil smoke drifted in through the console. I also suspect it is the cam cover gaskets are leaking and have bought a replacement set.

Big Dave

Are you guys sure that the cam covers need to come off to change the rear plugs? They look to me like it would be an easy job with the air box off. My engine is out of course, but the plugs are only held in place by a plastic arm and one bolt each.

Mongo

maybe it is my valve covers, and there is blow back onto the plugs. Needless to say I bet it'd be a good idea to do both. If the rear cam plug seals can be done with no sweat, I'll work on them on Saturday after the autocrosses. I can't seem to find in the shop manual where they work on the plugs and replace the seals. I see a blown up parts diagram and installation of the cams. But they don't really say how to take the seals and plugs out. Must be real simple if they didn't include it. They also didn't include the valve cover gasket replacement.

Tails

Andy,

It sounds like the cam end covers and the camshaft covers may need to come off, however, I would still suggest that you clean up the area to 100% verify where the leaks are coming from, so that you know exactly what need to come off. No need to remove anything that is not leaking unless you get to a situation of WYAIT(whilst you are in there).

The cam end covers can be removed in situ, but many report that it is a real PIA job.

Tails 1990 928 S4 Auto

Chris

Like Dave says those rear cam seals are a PIA to get at, much easier with the engine out for sure and much easier to get a good seal that way too. Cam covers definately have to come off.

I had a hard time getting them to seal with engine in situ, 1st time I didn't use the loctite 574 between the upper and lower metal housing (my own fault for sure, lesson learned), the 2nd is that these seals are mean to be pressed in not clamped as you will have to do with the engine in the car. This means that it is very easy to 'pinch' the cam plugs which will means the housing will not seal.

Anyway good luck, just make sure you replace all the seals you can while you are in there because if they wern't leaking before they will once you have messed with them !!

Chris

Mongo

Tails have you ever done cam plugs before? you sound pretty knowledgable on them. I know that the valve covers on both sides HAVE to be done since both had traces of oil and sludge when i looked and cleaned those areas. I hear it's a PITA to change the passenger side valve cover. Anyone have a procedure on how to do the rear cam plugs?? The only way I'm gonna learn this car is if I start doing my own repairs.