Update: Plumes of greyish smoke!!!

joe_keefer · Post by **joe_keefer** » Thu Apr 14, 2011 9:38 pm

hi guys,

well a new problem. when i started my car this morning i had a steady stream of thick grey smoke coming from the tailpipe. it's pretty light in color, but not white. it smells of burned oil, or fuel, and there are no visable signs of leaks. i've checked the oil and coolant. both are the correct color, but they were both quite low. now it has a very high mileage engine 450k-500k. so i'm getting use to refilling the oil. the head was rebuilt, if that can shorten the list. i also started it again this afternoon and again tonight. same problem.

any help would be much appreciated!

thanks, joe

well i've now got it apart and it appears that it was actually the head gasket. all the material between 5+6 was gone. it also gave me the chance to pull the #6 injector to see what it's major malfuntion was. the pintle cap was melted to the injector tip/pin. so while i have it apart, is there a simple way to tell just how bad the rings are?

thank you, joe

DEMIURGE · Post by **DEMIURGE** » Fri Apr 15, 2011 3:16 am

Hi Joe,

You are probably right - the engine is burning oil and the smoke is light grey. The dark grey smoke is usually unburned fuel (overriched mixture), if the smoke is white - normal at cold start with water condense and if the smoke remains after the engine is warm and hot - it is probably coolant leak.

It is important to know if this smoke appeared suddenly or not.

Regarding the reasons of burning oil - every amount of oil, burned in the combustion chamber:
1. The head was rebuilt, but the probable reason can be the valve seals, if they were not changed.
2. Head gasket - I strongly believe - it is not the reason.
3. Piston rings - stick or broken (sudden smoke) or very worn rings (increasing smoke) - check your spark plugs for oiling.

joe_keefer · Post by **joe_keefer** » Fri Apr 15, 2011 6:04 am

thanks alexander,

there has been some smoke already. just a little compared to this. it nearly stops when the engine comes to temp. so i guess the rings have just had it. that could also be why #6 doesn't work also. i am going to check compresion this weekend. so i guess i will know more in the morning.

Mike W. · Post by **Mike W.** » Fri Apr 15, 2011 11:34 am

More likely the valve guide seals than the rings, but with half a million miles on it who knows.

joe_keefer · Post by **joe_keefer** » Fri Apr 15, 2011 3:10 pm

Mike W. wrote:More likely the valve guide seals than the rings, but with half a million miles on it who knows.

so, i have a 3.3 from an 80 733i that i was going to rebuild and replace my 2.8 with. can i just use the head to check this? if so, which cam, and gasket should i use?

Post by **John in Simi Valley** » Sun Apr 17, 2011 3:40 pm

As Demirge mentioned, check the spark plugs for oil fouling.
Usually if the seepage is coming in from the valve guides, the plugs will have noticeable carbon buildup on ONE SIDE facing the source. If it's generally all oily, then more likely the rings.

Friendly Recommendation: use heavier grade oil. I don't see what weight you're using, but 20w50 is typical (you prob already know this). Verify. If so, then try going with thicker oil. Couple ways to do this is; Find a heavier oil 50 weight or 30w60 racing oil. Otherwise use 20w50 with a can of STP oil treatment. It will keep the consumption down and increase your oil pressure besides. When troubleshooting, DO THE SIMPLE THINGS FIRST. This is a cheap and simple test and should get you by.

Regarding cylinder #6 -- (As explained to me by <a href="http://www.beemerpros.com">Hal Epstein </a>) this us an unfortunate design flaw with the fuel system. The incoming fuel line enters the fuel rail directly over the #6 fuel injector. Being so, the hydraulic head pressure is substancially greater than the others, so when the motor runs at low speeds, #6 tends to get more fuel, washing the oil away from the cylinder walls causing #6 piston rings to wear at a faster rate.

Mike W. · Post by **Mike W.** » Sun Apr 17, 2011 9:49 pm

joe_keefer wrote:
Mike W. wrote:More likely the valve guide seals than the rings, but with half a million miles on it who knows.

so, i have a 3.3 from an 80 733i that i was going to rebuild and replace my 2.8 with. can i just use the head to check this? if so, which cam, and gasket should i use?

An 80 E23 came with the same head and cam as a 528i. Use a 2.8 headset, you need to match the gasket with the bore. Check it carefully first for cracks, 80's weren't the real fragile early heads, but not as good as later ones either.

joe_keefer · Post by **joe_keefer** » Mon Apr 18, 2011 6:31 am

An 80 E23 came with the same head and cam as a 528i. Use a 2.8 headset, you need to match the gasket with the bore. Check it carefully first for cracks, 80's weren't the real fragile early heads, but not as good as later ones either.[/quote]

thanks mike it has a casting date of 86 if i'm reading it right. i've cleaned it up pretty good, and can't find any cracks. thanks for your help!

joe