Lots of smoke from crankcase--Turbo problem??

[Rob4]

Can somebody help me? truck ran fine after 100 mile trip. The engine ran cool with no sign of trouble. Next day after 10 mile triip from town lots of smoke was coming out from around the dip stick tube and oil filler tube. Also, some smoke from exhaust. Code showed a balance fault at #3 cylinder. I checked the turbo-- no end play but a lot of side to side play. The inlet side vanes turn with the engine running but it doesn,t seem to spool up. There is no engine noise or knock but it does seem to run a little rough. Could a bad turbo bearing be somehow allowing smoke to get into the crankcase? This smoke appears right after start up, the engine doesn.t need to warm up for the smoke to appear. Any ideas other than the fact that the turbo decided to quit working at the same time another unrelated problem developed? Wouldn't a broken ring or cracked piston cause some kind of engine noise? Could #3 piston have a hole in it? Thanks for any help you can provide.

[ronniejoe]

Sorry to say this, but... a recently venthilated piston is the likely culprit.

[jspringator]

RJ, how much smoke coming out of the oil filler is too much? I have just a very slight white puff (kind of hard to see), and of course micro oil particles coming out. Is that OK?

[ronniejoe]

With the CDR hooked up and functioning properly, you shouldn't see any vapor out of the oil fill tube. High mileage engines might see a little...very little. If you are looking really hard to see something, you're probably OK. I noticed my other engine huffing out the oil fill tube about three months before it blew up. There was a noticeable vapor cloud coming out at idle.

[Rob4]

When I said that there was smoke coming from the crankcase, I mean that there is LOTS of smoke coming out from the oil dipstick tube and oil filler tube. It was just bellowing out--about like what you see coming out of the exhaust on a cold morning. Can anything cause this besides a bad piston?

[bobt]

I was cruising the interstate when I encountered the symptoms you describe. However, I also experienced a noticable jolt and subsequent drag in the engine and the engine was also blowing oil out the oil filler cap . I was told by a Chevy mechanic that my #8 cylinder was shot. I had overheated this stock engine several times in the past and I attributed part of the problem to this.
Bob

[bluuzman]

just curious.. How does the PCM detect a cylinder balance fault?

-ari

[BobND]

The PCM is looking for a certain amount of crankshaft acceleration (sensed by the crank position sensor) as each cylinder "fires". If it sees less acceleration at a firing event than it expects for a given load, fuel rate, and RPM, it sets a code for that cylinder.

[bluuzman]

ok, thanks I got the idea now.

However, a quote from a manual:

"DIAGNOSTIC TROUBLE CODE (DTC) 91-98 WILL SET WHEN
....
-Fuel correction amount exceeds defined limits for 2 seconds."

Based on what said above, there is a certain amount of compensation allowed/performed by the PCM to keep cylinders balanced. If the needed correction is out of some predefined range, the code will set.

Do you know what is the resolution for the crankshaft position sensor?
(might well find this in some manual... )

-ari

[ronniejoe]

Your event sounds just like what happened to my other engine in January of 2005. Check out the Part I article in the members area by clicking the link in my signature. A venthilated piston is about the only thing that will cause what you are describing.

[JohnC]

Do you know what is the resolution for the crankshaft position sensor?

The crank sensor generates a pulse every 90*. The optical sensor in the injection pump is much higher resolution, and I wouldn't be surprised if that's the sensor that's actually used for cylinder balance. As Bob stated, the PCM adjusts the fuel rate to each cylinder in an attempt to balance things and sets a code when a cylinder doesn't come in with the allowed correction.