Hello All -its been awhile . . . . down to one diesel, a MB '75 NA W115 300D. The engine is a MB reman and I initially noticed no oil consumption (Delo 15/40) but then had plenty of consumption which I attributed to freeway cruising at 70 mph and higher rpms. During this time, I also noticed leakage around oil filler opening on valve cover (engine has almost zero blow by) and the leakage was not heavy but more of a heavy film versus a drip. I pulled cap to clean and gasket broke as it was brittle and replaced with another metal oil filler cap that I had which had a much better gasket. I now have no leakage and no consumption! How could this be? Any ideas? Thanks!

Do you want leakage and oil consumption?

Blow-by gets worse if you drive at high speed. Oil will be thin, so if the gasket of the oil-filler cap is worn-out, oil will escape through there.

The gasket of the oil-filler cap can be replaced.

just happen to changing mine, part numbs are:


102 018 03 80 wider or
111 018 00 80

you have to check the type first.


cheers

__________________
w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered

Seems hard to believe I could lose so much via the cap without evidence of a messy engine bay unless the oil stream/vapor was being pulled under the car and away . . . For now, its nice to see the oil level on the dipstick not dropping!

A bead of grease applied to the valve cover works in a pinch.

__________________
CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

There might be another issue. The IP of the 300D gets its oil from the engine oil circuit. That means that diesel leakage in the IP ends up in the engine oil. The lighter diesel might be able to pass the oil-filler cap gasket and to evaporate. Now that you have closed that route, the diesel stays in the engine oil and keeps the level up.

Hmmm . . . . I would think my engine oil would appear to be highly dilute and thin under these circumstances, yes? Any definitive tests for checking for fuel in the oil sump? Thanks! I have noticed that the oil level stays at the same point on the dipstick. I would think with a leaky IP that I would see some rising and other strange readings on the dipstick -thanks again!

Make sure your vacuum pump vent line has not got oil inside. Oil processed through a leaky vacuum pump diaphram gets fed to the intake and burnt. The line should be fairly clean.

I am thinking at high rpms it may process some but not at lower rpms. The design of the vent line was changed later to feed basically back into the crankcase. Just something to consider. highway revs of an older 115 car are high at seventy and usually will increase oil use a little.

If the breathing vent from the engine to deal with base pressure where blocked then The oil cap being sealed or not might make a differance. I am not sure exactly where that venting hose is on your earlier engine. Common place is right on top of the valve cover though. Although sealing the oil fill hole should make the problem even worse if the main vent line was obstructed. You may also have missed an engine leak that is only really active at high rpms. I guess I have to also ask what amount of oil in quantity was absent in how many miles.

Thanks! No oil in vac line entering manifold, line looks clean, have not checked the other circuit headed to Brake Booster. I just drove the car very actively without a trace of consumption and at sustained freeway speeds of 65 to 70 . . . my breather runs to the intake manifold

I wonder when your oil level dropped then if it was a case of built up water condensate from slow around town usage, Then out on the highway you boiled the water off. I have seen this before on a couple of gas cars. One dropping two quarts in 125 miles. The car had just been aquired and the past owner probably only did very very short trips with it. Building condensation up over time.

Did you ever figure this out? I just noticed around half a quart of consumption after 1000 miles of highway driving at 50-75 mph. My W115 240D has never noticeably consumed oil before and I just changed the oil 1000 miles ago.

A few points:

1. I have had enough blow by to make the cap dance but not fly off since I purchased the car
2. Compression, power, performance and economy are very good.
3. Valve adjustment done
4. Diesel purge done
5. Fuel system ancillaries are all new or renewed and the car is obsessively maintained

__________________
Why I will never do business with "DieselKraut" again

http://www.peachparts.com/shopforum/mercedes-benz-used-parts-sale-wanted/378935-why-i-will-never-do-business-dieselkraut-again.html

This to me is not extremely abnormal. Especially on the 616s as they rev so high at the speed you indicated.


When these engines where new. I think the manufacturer required straight 40 grade oil. As it was possibly before multigrades.


A straight 40 grade oil will signifigantly lower oil consumption over a say 15/40. At higher highway speeds. You could run the straight forty in the warmer season if you reside where it gets cold in the winter.