'92 300e - PeachParts Mercedes-Benz Forum

#1 10-20-2004, 08:07 PM

I am at the point to make effort to stop the oil loss on the MB. After having it for 4K miles now...it goes thru a quart of oil in approx. 700 miles. Testing after a complete oil change. It does not leak any oil on the ground or leave anything more than a slight trace on the under pan. Nothing like 4 quarts that have been lost in less than 3 thousand miles since I changed oil. The plugs don't show oily like my 190E did that the quides were worn out in. It doesn't appear to smoke any either. I was wondering if there was anything I should check possibly for the problem before I tear the top end down? The car has 90K on it, and has had the oil & filter changed in a mercedes dealership every 3 thousand miles. I, also, would like to know if it is guide problems in this car also...if there are any better ones I can get to use than factory ones. I wouldn't want to have to redo this again, if in fact that is the problem. Any help or advice that you can offer would be appreciated. Thanks, Rebe

dirtysocks · #2 10-21-2004, 03:15 AM

VERY typical problem with the m103 engine. Look all around and below valve cover gasket, and just under the distributor cap for signs of oil, probably need to clean the engine with some degreaser first. This engine will usually leak from these two spots when running, so oil does not really collect in the underpan or on the driveway.

p.s. A search should bring up a ton of info on this.

neanderthal · #3 10-21-2004, 03:24 AM

i think he meant the radiator cap.
use a thicker oil. get ready for a top rebuild.

dirtysocks · #4 10-21-2004, 03:51 AM

Did you mean that I meant radiator cap, neanderthal? Huh? I was talking about the upper timing cover.

Also, I think it is a bit premature to be talking about rebuilding the entire top end. Many people on this forum have had similar oil leaks that were fixed by much less than a full rebuild. It only has 90k.

nglitz · #5 10-21-2004, 10:27 AM

Read Lino's thread "M103 Oil leak or burning" Exactly this problem. Lotsa pictures.

Bruno_300TE · #6 10-21-2004, 10:50 AM

The typical leaks of the timing chain cover or valve cover gasket cannot account for an oil consumption of 1 quart per 700 miles. If so, you would find a big puddle under the car. It must be burnt.
Regards, Bruno

michael cole · #7 10-21-2004, 03:25 PM

my theory on this.at higher engine rpm more oil is present on top of engine splashing around and possibly turning to oil mist at which point this oil mist is sucked up the pcv hose into the intake manifold where in small but significant quantities it will mix with more air and fuel and easily burn off in the combustion chamber.my 300e seems to consume more oil on highway runs.i have taken care of the obvious like valve cover gasket,filler cap.plug fouling is minimal

Jackd · #8 10-21-2004, 03:59 PM

Valve guides/valve seals time
jackD

#9 10-21-2004, 05:21 PM

I call the shop forum parts department today. He told me he didn't sell many guides for this mercedes, but valve seals. So, maybe it just needs seals if what he tells me is correct. I am not real familiar with the engine to know how to separate out if it is seals or guides.

psfred · #10 10-21-2004, 07:06 PM

If the plugs are clean, as they probably are, replace the oil filler cap and valve cover gasket before getting too excited.

The cap will ONLY leak at speed, when oil is thrown off the cam onto it, it won't leak idling or in town. Clue is that there is always oil around the filler cap even if you wipe it dry carefully betweel fills. The oil will run down the head and off the rear of the engine, and since there is so much, and it's hot, it won't collect the black crusty stuff a typical leak does.

If you smell burning oil occasionally, the valve cover gasket is leaking all round, too, replace.

Front cam cover seal is also a known leak on these cars, but that usually causes oil to run of the oil pan. Not always, though -- that sound panel under there holds quite a bit.

If the plugs are crusty, time of a valve job.

A quart in 700 miles with bad guides would be obvious from the blue smoke on startup and after sitting at lights.

Peter

#11 10-21-2004, 07:51 PM

PSFRED I noticed you have a 300E with 220K on it. How did it do on oil consumption, and has the guides or valve stem seals ever been replaced and at what milage if they did?

psfred · #12 10-21-2004, 07:57 PM

It had a valve job with new valves, guides, cam, and rockers at 160,000 miles (and a notation on the bill that it needed to have the oil changed much more often..... I bought it at 196,000).

It used about a quart in 1200 when I got it a reeked of oil smoke on the highway -- new valve cover gasket dropped the consumption some, but the rear cure was the new oil filler cap.

Just replaced the gasket again (cover has been off a couple time for various reasons) to cure an oil smell, but it's only using a quart in 3000 miles or so now, maybe less.

Peter

stevebfl · #13 10-21-2004, 09:06 PM

The valve guide seals are simple and relatively cheap and always the problem. If the guides are wore the seals won't last as long. Even poor guides are usually sealed for 10-20k with new seals.

There is no reason to rebuild the whole head untill the seals don't last but 10k or so