M103 Oil leak or burning? - PeachParts Mercedes-Benz Forum

lino · #1 09-05-2004, 05:51 PM

My 1989 M103 engine is losing oil. I'm not sure if it's buring or leaking.

I have read that the M103 leaks Oil at Top of the Timing Chain Cover, because of the gasket. I have also read that the M103 leaks Oil near the right rear of the engine block - Head gasket. I'm not sure how much oil the M103 engine normally burns.

In my car I see some oil on the plastic guard under the engine below the alternator. I'm not sure if it's freah oil or old. The right rear of the engine block looks dry. I took a quick glance. I will give it a thorough look and then I will clean the engine to see if there are any visible leaks/spots. I'm not sure if the engine is burning oil either. The previous owner spent a lot of money maintaing the car. I was looking in the service records and found this:

14MAY99 189 338 km
Wheels - Two, R & R $57.32
Brake Pads Rear R & R $19.92
Cylinder Head - Single, R & R $602.91
Replaced Exhaust Manifold Gaskets $99.60
Engine Cooling System, Flush $349.21
Inner Door Panel - On One Front Door, R & R $490.64
Door Lock Cylinder - For L/Front Door, R & R /Replace If Required $33.20
TOTAL $1652.80

27OCT97 179 989 km
Exhaust System - After Catalyst/Front Pipe Connection, Replaced $612.89
Belt Tensioner Shock Absorber - Single Belt Drive Replaced $91.23
Automatic Transmission (722.0 TO 722.4) R & R $356.40
Crankshaft Driven Plate/ Ring Gear R & R $32.40
Starter Motor Replaced ( While Transmission Is Removed) $446.92
TOTAL $1539.84

***Cylinder Head - Single, R & R $602.91
Does this mean the Head Gasket was replaced?

BTW- Does anyone know what this is:
***Automatic Transmission (722.0 TO 722.4) R & R $356.40

Thanks in Advance

sixto · #2 09-05-2004, 06:03 PM

Check for an oil leak on the front right of the engine below and behind the distributor. It will leak down to the alternator then to the plastic cover or ground. You can ususally fix this leak with a new horseshoe gasket.

Sixto
95 S420
87 300SDL

lino · #3 09-05-2004, 06:25 PM

Quote:

Originally Posted by sixto

Check for an oil leak on the front right of the engine below and behind the distributor. It will leak down to the alternator then to the plastic cover or ground. You can ususally fix this leak with a new horseshoe gasket.

Sixto
95 S420
87 300SDL

I will take a look. Thank you very much.

Gilly · #4 09-05-2004, 09:06 PM

Yes the "R&R headgasket" means the headgasket was replaced.
The other one, the R&R Transmission 722.0-722.4 means the transmission was removed. It's all rather cryptic, but I am assuming they may have had to replace a cracked "flex plate", which is what drives the torque converter. Either that or there is more to that work order you're not saying, like they resealed the front pump in the transmission, or replaced the rear main seal in the engine, something like that. No other good reason to R&R (remove and reinstall) the transmission.
The "right rear" leak on the engine, that's not common in this engine, it's common in the dual cam (M104) engine, not the M103.
I agree that what is referred to as the "horseshoe gasket" (first time I think I've heard it called that!) could be the problem. They HAVE to use the correct sealant on this job or it won't last long. The PROPER sealant is ONLY Loctite 5900, and the procedures must be followed, especially in terms of cleanliness and cure time of at LEAST 2 hours, I prefer an overnight curing time if possible (do the job in the afternoon and do NOT start engine until the next day). The seal is usually referred to as the "lip seal", also called the cylinder head front cover lip seal. It's not a gasket it's a rubber profile seal.

Depending on miles, etc and how bad the leak actually is, the problem could also be the valve stem seals. Usually a quick spark plug inspection will reveal if these are worn out or not (heavy deposits on the plugs, usually a normal tannish color and may have a "glazed over" look to them. The seals are replaceable without removing the head by using compressed air to pressurize the combustion chambers, then the valve springs can be removed and the seals easily pop off and on.

Gilly

lino · #5 09-06-2004, 12:53 AM

Thanks Gilly for that detailed response! I was using the SEARCH button earlier and did some reading about the "lip seal" as you call it and it I think that might be my problem. I will check to confirm as soon as possible.

My car has a little under 120,000 miles on it. I changed the spark plugs approximately 2000 miles ago. The plugs that were in the car looked like new. My mechanic said that they looked like they had 6000 miles on them at most. I changed the oil too and it was clean. I'm using Liqui Moly 10W40. When I went to change the air filter, I found a K&N filter which was also clean. I wonder if my valve stem seals need to be replaced.

I have most of the service records for my car. I am missing some of the last ones and you can see them in this thread. Look at post #12:

http://www.peachparts.com/shopforum/showthread.php?t=96057&highlight=Driven+Plate

Gilly · #6 09-06-2004, 04:49 AM

I'll try to look at the service history later. In general the spark plug deposits are the key thing to look for in determining if the valve stem seals are shot. The usual complaint is a poor cold start; it'll do what's called a "false start" in the morning, on the second attempt it'll start right up. Occasionally the complaint is long cranking times to start.

Gilly

psfred · #7 09-06-2004, 12:22 PM

Two quick and fairly easy things cause oil leaks on these cars -- bad oil filler cap and bad valve cover gasket.

The filler cap is plastic, and they crack. Causes about a quart in 800 miles or so oil use if you do any highway driving, and doesn't always show oil drips because it only leaks on the highway. Clue is that the depression around the cap will always have oil in it even if you remove the cap and wipe it up. Oil runs down the front of the engine, looks exactly like a top chain cover leak except there is more on the left side (where you cannot see it easily).

New filler cap is a couple bucks, less than a quart of semi-synthetic oil.

The other leak is the valve cover gasket -- they get rock hard and crack through the seal surface after about 30,000 miles or so, and dribble oil everywhere, but mostly out the exhaust side. It burns off the manifold when they really get bad, so if you smell burning oil after a highway run once in a while, replace the gasket. Instructions have been posted, but you MUST get the valve cover and head completely clean and dry before installation and must not use ANY sealant on the valve cover gasket, else they always leak! I always wipe the head down with solvent where the gasket seats, never had a leak with a new gasket.

Older M103s would be needing valve guides by now (the TE got a valve job at 160,000 miles), but an 89 should have the harder guides. You'd see serious oil ash deposits on the plugs if this were the case, though!

Peter

autozen · #8 09-06-2004, 09:57 PM

If you don't find any leaks, I'm bettin on the guides. My experience with these engines has been that worn seals will cause smoking, and worn guides will cause oil consumption. They should have been done while the head was off.

Peter

lino · #9 09-11-2004, 03:24 PM

Please accept my apologies gentelmen. I had a heck of a week. Here are responses to all of you in no paricular order. I will have to probably do multiple posts due to the number of pics.

psfred:
I checked the oil filler cap and it looks fine. There is no visible sign of oil leaking from there. I have a spare oil filler cap that I bought from the Mercedes dealer for my W201 2.3 8v. It has approximately 20,000 miles on it. Is it the same as the W124 cap? I was thinking of replacing it anyway with this one. Here are pics:

Part # 111 018 03 02 REUTTER

Should I replace it with one?

lino · #10 09-11-2004, 03:37 PM

Gilly:

Here are pics of my spark plugs. They are in order from 1 through 6:

Spark Plug 1:

Spark Plug 2:

Spark Plug 3:

Spark Plug 4:

Spark Plug 5:

Spark Plug 6:

psfred · #11 09-11-2004, 03:42 PM

I can't tell from the pics, are they wet and oily or just covered with fluffy black stuff?

If dry, you are running WAY rich, you have a fuel problem. If bad enough, this can cause excess oil consumption due to oil dilution (this is VERY bad for the engine, by the way).

Îf oily, it's valve guide time. You would be making smoke at that oil consumption rate, too.

Peter

lino · #12 09-11-2004, 03:45 PM

I have some pictures of the engine that I am sorting through right now. May camera is entry level 2.o megapixel Sony and so quality is not the greatest, or maybe it's my photo-taking skills that not so good

. Anyway, I'm reducing the size and cropping. I'll post them soon.

Thanks everyone!

lino · #13 09-12-2004, 03:16 AM

Quote:

Originally Posted by psfred

I can't tell from the pics, are they wet and oily or just covered with fluffy black stuff?

If dry, you are running WAY rich, you have a fuel problem. If bad enough, this can cause excess oil consumption due to oil dilution (this is VERY bad for the engine, by the way).

Îf oily, it's valve guide time. You would be making smoke at that oil consumption rate, too.

Peter

Those pictures are of the spark plugs I took out of the car appoximately 3000 miles ago. They were the ones that were in the car when I bought it. I saved them and labelled them. I do apologize for the quality of the pictures. I will take another set when the batteries finish recharging, because the plugs in reality are much lighter in color. I just looked very carefully at them again and they are not as black as they look in those pictures. I am looking at the inside cover of a Haynes manual that describes the different types of spark plug conditions. I think this is in the inside cover of all the Haynes Manuals.

1. Normal - Mine look very close to this.
2. Worn - Mine do not look like this.
3. Carbon Deposits - Sort of like this.
4. Ash Deposits - Mine do not look like this.
5. Oil Deposits - Maybe ever so slightly.
6. Gap Bridging - Mine do not look like this.
7. Too Hot - Mine do not look like this.
8. Preignition - Mine do not look like this.
9. High Speed Glazing - Mine do not look like this.
10. Detonation - Mine do not look like this.
11. Mechanical Damage - Mine do not look like this.

lino · #14 09-12-2004, 03:30 AM

Here are some pictures of the engine on the passenger side. Sorry about the quality. The sun was out and I still haven't figured out how to take good pictures with this camera.