Smoke inside the engine bay. - PeachParts Mercedes-Benz Forum

alfa 75 · #1 11-24-2008, 07:01 PM

1984 300D- this started fairly recently: I have smoke coming from the engine bay. It's not very thick, it's a white-ish/borderline clear smoke, it's coming from the rear area of the engine but I can't tell which side (looks like it could be both.) It mostly happens when the engine is revved up but sometimes at idle, and it keeps smoking after the car is turned off. I cannot for the life of me pinpoint where it's coming from.

The car has an oil leak coming from the back of the engine (which started last weekend after a 150 mile freeway drive), I haven't had time to find out what's leaking, the two could be related? It has good oil pressure, good power, doesn't overheat, it drives fine, no issues otherwise.

Thoughts?

79Mercy · #2 11-24-2008, 07:21 PM

check and make sure the valve cover gasket isn't leaking. Also check the head gasket.

ascalise · #3 11-24-2008, 07:24 PM

Sounds like an exhaust leak. I just fixed mine. (EGR tube)

alfa 75 · #4 11-24-2008, 07:37 PM

Headgasket- that's what I don't want to hear, but it was also my first guess. Seems like I'd notice some symptom- smoke out the exhaust, oil in coolant or vice versa, lack of power, etc. I just did the valve cover gasket and it's not leaking anywhere.

Exhaust leak is a possibility, I'll check, thanks.

alfa 75 · #5 11-24-2008, 07:38 PM

EGR tube.. hmm.. could you give me more info about that? I'll do a search, too.

79Mercy · #6 11-24-2008, 07:39 PM

do you smell anything burning? If not then its probably a exhaust leak.

BTW, did you mail my triangle? Thanks

alfa 75 · #7 11-24-2008, 07:41 PM

Quote:

Originally Posted by 79Mercy

do you smell anything burning? If not then its probably a exhaust leak.

BTW, did you mail my triangle? Thanks

I've emailed you about it- I'm doing it first thing tomorrow. And neah, I don't smell anything burning. I'll get it up on jacks tomorrow and check, thank you.

79Mercy · #8 11-24-2008, 07:50 PM

then its probably not a oil leak or any type of fluid leak. Its just probably an exhaust leak. Good luck, let us know.

Thanks again for the /\..

alfa 75 · #9 11-24-2008, 07:53 PM

If it adds anything to the discussion, I had my whole air filter housing off two weekends ago to figure out why it was rattling so much (missing a mount- go figure.)

Edit: I did some research on the EGR- looks like it's towards the front of the engine, the leak seems to come from the back.

alfa 75 · #10 11-25-2008, 04:31 PM

Update:

I crawled under the car during my break, the leak from the back of the engine comes from the oil filter housing area. It's NOT the cap, the cap is on tight and it has a seal. It would also appear that the smoke comes from there.

The smoke is not an exhaust leak as it only happens when the car is hot. Most of the time it happens after the car is shut off.

UriahT · #11 11-25-2008, 05:55 PM

Make sure your engine oil is not overfilled.
Can cause seals to burst by increasing internal pressure. Keep it near the low mark for safety.
You might also try the soapy water trick to see where bubbles form to spot the exact place its leaking.

alfa 75 · #12 11-25-2008, 06:39 PM

It's not overfilled, it's about 2/3 of the way up the dipstick (I check it almost daily.) My main concern isn't the leak, it's the smoke that comes out of it which I believe may be related to the leak. Since it only happens when the car is hot, could it be that oil drips onto the hot engine and burns? Could it be oil vapor?

Johnhef · #13 11-25-2008, 07:39 PM

The key is you had the air filter housing off, the oil drain tube from the housing to the pan is most likely not seated on the fitting in the housing and blowby gases are leaking out.

t walgamuth · #14 11-26-2008, 06:15 AM

It does not sound like head gasket to me. If it were manifold leak you would hear a pfht pfht noise when the car is running. My first thought was a minor oil leak onto the hot exhaust, but that would make a burning smell. It its a small coolant leak it could do what you say, and there are hoses running here and there for the heater, so just keep looking til you find the source.

alfa 75 · #15 11-26-2008, 10:37 AM

Quote:

Originally Posted by Johnhef

The key is you had the air filter housing off, the oil drain tube from the housing to the pan is most likely not seated on the fitting in the housing and blowby gases are leaking out.

I checked that but it doesn't seem to be it.. though I'll double check, because my air filter is VERY loose (gotta fix it this week). With the car off it sits tightly on the fitting but who knows what happens with the car off.

I don't think it's a coolant leak, it doesn't lose coolant.

Thanks for the suggestions.