Oil in prechambers? Oily injector tips? - PeachParts Mercedes-Benz Forum

andrewjtx · #1 12-30-2013, 09:40 AM

I've been running through a few pre-sale maintenance items and have made my way to the GPs and injectors.

Wanted to get both 100% up to snuff and I've had Monarks waiting to be installed for a few months.

So I pull the injectors to find that #1 & #4 have a fair amount of oil in the prechamber. The tips on those injectors were dripping with motor oil when I removed them.

What might this indicate? Leaking valve stem seals?

ichris93 · #2 12-30-2013, 09:47 AM

Quote:

Originally Posted by andrewjtx

I've been running through a few pre-sale maintenance items and have made my way to the GPs and injectors.

Wanted to get both 100% up to snuff and I've had Monarks waiting to be installed for a few months.

So I pull the injectors to find that #1 & #4 have a fair amount of oil in the prechamber. The tips on those injectors were dripping with motor oil when I removed them.

What might this indicate? Leaking valve stem seals?

Do you have a compression tester? Might as well run a test while doing GPs and injectors. Plus it will be good to know for listing it for sale.

andrewjtx · #3 12-30-2013, 09:53 AM

I do and it's on my list.

eatont9999 · #4 12-30-2013, 11:10 AM

I have seen that in engines with good compression, etc. I believe it is residual oil from valve cover leaks or removal that works down the prechamber areas and sits on the injector until you remove it.

cooljjay · #5 12-30-2013, 11:49 AM

Which year car is this on?

eatont9999 · #6 12-30-2013, 12:09 PM

Only assuming but this one?:

'85 300TD "Puff The Magic Wagon" - prepping for sale

andrewjtx · #7 12-30-2013, 12:17 PM

Correct. Sorry for the omission.

Diesel911 · #8 12-30-2013, 01:29 PM

Look inside the Prechamber itself. If the whole prechamber has shiny wet looking carbon the Oil is coming from inside. If Oil was getting in there for a long period of time there will be a slightly thick build up.
Normal would be to look inside and see the whole Pre-chamber coated with a light buildup of dry carbon.

You did not say if the Engine was running well or not. If it was having bad misses due to an Injector not atomizing enough to burn the Fuel Well your Piston Rings will not do a good job of scarping the Oil off of the Cylinder Walls and that is one way to get Oil up into the Prechamber. Good combustion pushes the Rings against the Cylider Wall scraping off excess Oil.

If you want to determine if the Oil is coming from somplace else besides the Cylinders pull of the Intake Manifold and inspect the exhaust and intake ports in the head and in the Manifold.
If the Valve Guids are passing Oil due to wear or bad seal you would likely see that inside of the Ports in the Head.
If the Oil is coming from the Turbo you will see that in the intake Manifold and it will also be oily in the intake ports of the Head.

andrewjtx · #9 12-30-2013, 02:54 PM

Engine would run well when on the road. I could do 85 (maybe more

on the toll roads) Idle was inconsistent when hot after a long spirited run.

Cold starts were a problem but all GPs glowed when I pulled them. Once the engine would turn over, I would fog the neighborhood with blue/white smoke for the first minute or so. GP holes were reamed out with little to no resistance.

Fuel mileage on the current injectors was always right at 20mpg. Oil loss was about 1-2qt/3k miles. But It needs new seals on oil return tubes and oil filter housing. I may or may not have time to get these done before I want to sell.

Not thrilled about pulling the IM, but I want to make sure this car is in top running order before passing off to the next owner.

Diesel911 · #10 12-30-2013, 08:01 PM

Quote:

Originally Posted by andrewjtx

Engine would run well when on the road. I could do 85 (maybe more

on the toll roads) Idle was inconsistent when hot after a long spirited run.

Cold starts were a problem but all GPs glowed when I pulled them. Once the engine would turn over, I would fog the neighborhood with blue/white smoke for the first minute or so. GP holes were reamed out with little to no resistance.

Fuel mileage on the current injectors was always right at 20mpg. Oil loss was about 1-2qt/3k miles. But It needs new seals on oil return tubes and oil filter housing. I may or may not have time to get these done before I want to sell.

Not thrilled about pulling the IM, but I want to make sure this car is in top running order before passing off to the next owner.

If you can tell if it was oil that entered from the out side dribbling into the Pre-chamber when you pulled the Injectors then it is not needed to pull the Manifolds.

whunter · #11 12-30-2013, 08:06 PM

Quote:

Originally Posted by andrewjtx

I've been running through a few pre-sale maintenance items and have made my way to the GPs and injectors.

Wanted to get both 100% up to snuff and I've had Monarks waiting to be installed for a few months.

So I pull the injectors to find that #1 & #4 have a fair amount of oil in the prechamber. The tips on those injectors were dripping with motor oil when I removed them.

What might this indicate? Leaking valve stem seals?

My first guess would be leaking injectors.

.

cooljjay · #12 12-31-2013, 12:01 AM

WOW 20mpg.....something is really up my non turbo gets 26mpg.....

Has a valve adjustment been done?

I said this on another thread...its possible the lift pump is sucking oil from the engine and depositing it into the injection system...

I have also read that bad valve steam seals will cause oil to leak in the combustion chamber....

whunter · #13 12-31-2013, 02:54 AM

Quote:

Originally Posted by cooljjay

WOW 20mpg.....something is really up my non turbo gets 26mpg.....

Has a valve adjustment been done?

I said this on another thread...its possible the lift pump is sucking oil from the engine and depositing it into the injection system...

I have also read that bad valve steam seals will cause oil to leak in the combustion chamber....

Two or more serious leaking injectors would explain the low MPG.

.

oldsinner111 · #14 12-31-2013, 05:21 AM

I heard if they leak to much,they can burn a hole thru the piston

andrewjtx · #15 12-31-2013, 10:06 AM

Looked at the injectors before taking them to the diesel shop this morning. Actual nozzle faces were all dry carbon, the sides of the tips were coated in oil. I think this is from previous VC gasket leaks as eatont9999 stated. I should have time to get a pen light down to the prechambers this evening.

The car was making good power, just poor mileage and less-than-stellar cold starts.