Still smokes after cylinder head rebuilt and gasket. - PeachParts Mercedes-Benz Forum

jmerc6 · #1 02-08-2009, 01:03 PM

Yesterday I took out my car after I got the cylinder head back on and every thing buttomed back down. After taking it on a 5 mile drive, when I parked it I noticed white smoke is still coming out of the exhaust. The car is '91 300 CE. Could it be residue oil still in the exhaust from before the rebuild, or is it something else? I've read where the engine will still start and run even if the timing is off a little.

ps2cho · #2 02-08-2009, 01:42 PM

It is gonna take more than 5 miles to get everything out of the system. On my rebuild it took about 20miles before the exhaust stopped blowing out white smoke.

el sea · #3 02-08-2009, 05:38 PM

FME:

If an engine has a lot of miles on it and you rework the top end, chances are you may pull oil pass the rings. Compression will improve with the rework with the newly seated valves, but oil consumption may get worse. All of this is because the new valves will be sucking oil pass the old rings and glazed cylinders. Another issue on the horizon, is the new fuels (ethanol) will degrade the oil on the upper end of the cylinders, causing additional wear compared to the older fuels.

el sea · #4 02-08-2009, 05:41 PM

If the engine has high miles you may be pulling oil pass the rings due to the new valve job. You may have to go to a high grade of oil.

Arthur Dalton · #5 02-08-2009, 05:51 PM

Check Booster vac line for brake fluid.............

jmerc6 · #6 02-08-2009, 09:59 PM

Do I disconnect the line to chk for brake fluid? If so, do I blow the line out or what? Thanks.

cliffmac · #7 02-08-2009, 10:02 PM

white smoke is coolant, not oil nor fuel (those are blue and black respectivly)....no, white is coolant and I would suggest you run it further and longer than a few minutes to allow everything to seat. I could go away with run-in....and it could be residual moisture in the exhaust that hasn't burned off after sitting for a period. I'd run it for 30 minutes and see if it doesn't clear up.....you undoubtedly changed the oil as part of the cylinder head job right? You must change the oil as part of a valve job....

jmerc6 · #8 02-08-2009, 10:10 PM

I did change the oil and filter. Put in new coolant. The car's front end has been jacked up about 18" for about 6 weeks. The motor doesn't have that many miles (148,000). But the head has been leaking for some time before I broke down the motor.

JonL · #9 02-09-2009, 01:01 AM

Does that car have a vacuum modulator for the transmission?

jmerc6 · #10 02-09-2009, 09:15 AM

Don 't know.

JonL · #11 02-09-2009, 10:10 AM

Find out. A bad vacuum modulator will allow the engine to suck up transmission fluid and create white smoke as you have described. If you have a vacuum modulator, pull the vacuum hose and see if there is fluid in it (there shouldn't be if the modulator is good). Check you transmission fluid... if it is low and there are no leaks that's a big hint, too. And of course if it's been shifting hard is a sign.

david s poole · #12 02-09-2009, 10:15 AM

you will find that coolant went into exhaust while engine left standing and has to burn out.i assume you drained radiator before you started but i bet you didn't drain coolant from the engine.

jmerc6 · #13 02-09-2009, 10:19 AM

Thanks for the tip. I'll check it. While I'm at it, I have another question. When I was reassembling the top timing cover I had an o ring package, but I couldn't find where it went. I researched the cds but I didn't see anything about an o-ring in the timing cover. Now I've noticed there's small leak around the timing cover. Could they be related?

connerm · #14 02-09-2009, 12:55 PM

White smoke can also be unburned fuel reaching hot exhaust manifold. Prior to ULSD, my high speed diesel dumps would produce big brown clouds of smoke. Now they produce white clouds. I miss the old days.

jmerc6 · #15 02-19-2009, 10:23 PM

Sorry I hadn't gotten back until now. I had an oil leak around the camshaft position sensor. Just got another one in today and the oil leak has stopped. The white smoke has also disappeared. After driving it for about 100 miles, it stopped.
Thanks to all who helped me through this process. It has been very satisifying to do this cylinder head gasket. I have gained confidence to tackle other repairs. I couldn't have done it without this forum.