yellowish stuff inside cylinders and on pistons - PeachParts Mercedes-Benz Forum

bgk202 · #1 03-30-2009, 09:14 PM

when I opened up my engine, on 2 of my 5 cylinders there was yellowish- orangish goop. Does anyone know what this is from? I was running a veg oil blend, could it be related to that? bad injectors? coolant or condensation? Let me know your thoughts, here's a pic:

JonL · #2 03-30-2009, 09:26 PM

Probably deposits left over from coolant that got in. I'm guessing you had a bad head gasket or head?

pawoSD · #3 03-30-2009, 09:29 PM

I don't think coolant turns to yellowish goop.....I think LARD does. WVO ruins engines alert!!!

JonL · #4 03-30-2009, 09:41 PM

Can't really tell from the picture what it looks like, but I've seen some nasty looking gunk on pistons from a blown head gasket. It's a mixture of the coolant additives and corrosion of the aluminum piston crown, with a little emulsified fuel and oil thrown in for flavor.

79Mercy · #5 03-30-2009, 10:11 PM

Why did you pull the head off? The WVO took its toll on another MB diesel, poor car.

bgk202 · #6 03-30-2009, 10:31 PM

The engine had poor compression in a few cylinders and lots of blowby coming out of the valvecover oil cap. I had a blown transmission so I had to pull the engine anyways.

Turns out 3 of 5 cylinders had broken rings and the rod and main bearings were burnt. Cylinders were perfect (no ridge), pistons, perfect, headgasket seemed good, had head magnafluxed and xrayed and it was good, crank was measured and magnafluxed and it was good.

question - the perplexing thing is that if it was veg oil that was the problem, why wouldn't the gunk be in all 5 cylinders and not just 2? The other 3 cylinders were gunk-free. I'm perplexed - thats why I'm asking you guys. If you want a higher resolution photo of the 2 cylinders let me know and I'll post it.

here is a pick of the whole block:

JonL · #7 03-30-2009, 11:07 PM

When you pulled the head, it wouldn't be at all unusual to have some residual coolant fall into the cylinder. If that happened and it sat that way for a time, you could get some kind of peculiar looking deposit. Just a possibility, I don't know what else it could be.

mplafleur · #8 03-31-2009, 06:41 AM

That's coolant. WVO had nothing to do with this.

strelnik · #9 03-31-2009, 06:47 AM

Quote:

Originally Posted by bgk202

The engine had poor compression in a few cylinders and lots of blowby coming out of the valvecover oil cap. I had a blown transmission so I had to pull the engine anyways.

Turns out 3 of 5 cylinders had broken rings and the rod and main bearings were burnt. here is a pick of the whole block:

That portion of the description indicates other problems to me more serious than goobers in the cylinders, which could happen any time once there are no rings to compress, ignite and exhaust.

Three cylinders with broken rings and no scratches on the cylinders per se?

Did the rings disintegrate, yet make no scratches? Curious.

pawoSD · #10 03-31-2009, 10:45 AM

The goop is probably in the cylinders that were not experiencing even combustion anymore due to low compression.....

Alastair · #11 03-31-2009, 10:53 AM

The stuff you see is just plain old carbon....

Not Always black. The hotter parts like exhaust-valves and the surface of thick carbon layers often go sandy/brown/reddish colours...

Just look at the coke/carbon on a well running gasser engine.....

IF you were in the UK where 'Rebated' diesel is available with a red-dye, This also transfers to the carbon in the engine...

Yup, You'll get red carbon in places like on the Pre-Chamber noses....

Diesel911 · #12 03-31-2009, 11:36 AM

What do you think caused cracked Rings?
The things that I can think of: I have seen Rings that were stuck compressed in the groove by Carbon Crack, cracked due to a hydraulic lock in the Cylinders or cracked because the owner could not shut off his Vehicle so he pushed the Car up against something in Drive and stalled the Engine.
After that I have no clue.

tbomachines · #13 03-31-2009, 11:44 AM

Quote:

Originally Posted by mplafleur

That's coolant. WVO had nothing to do with this.

X2

winmutt · #14 03-31-2009, 02:45 PM

Check your prechambers. See the dimples left on the piston crowns? Where is a picture of the head? Coloring is probably from the lack of prechambers and bad combustion.

Biodiesel300TD · #15 03-31-2009, 05:07 PM

I've seen similar stuff with a blown headgasket. When coolant and oil mix really well is turns an odd tanish orange color. And is all gooy. I too would guess a bad headgasket.