my 1992 300 CE has a oil leak at the back of the cylinder head. i have 86,000 miles on this vehicle and i want to remove the cylinder head, replace gaskets, valve seals, re-surface cylinder head, and replace head bolts. i am not to familiar with this type of engine and i would like to know if there is anything else i need to do to complete this job. because the engine has 86,000 miles on it, i do not want to replace to many parts. my other concern is what kind of special tools do i need in removing the cylinder head.


many thanks for your input.

You ought to be able to run the valve seals for awhile longer unless you are seeing smoke from the exhaust. About the only special tool required is the socket you will need for this models cylinder head bolts. The Snap On truck has em. The most pia part of the job, in my opinion, will be getting the front sealed properly. Do a search on here - lot's of write ups.

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Jim

Should be no need to surface the head, replace the head bolts, or valve stem seals. You can have a machine shop measure the head for flatness. The headbolts can be measured for stretch which rarely happens.

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Scott Diener
89 300E
93 300E
92 Volvo 740 Wagon aka "Mutt mover"

I would replace the valve guides, as they can only be replaced with the head removed. The valve seals can be replaced w/o removing the head.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

That's a lot of work to solve an oil leak on a car with only 86K miles. Cylinder head gaskets should not be the source of oil leaks except at the point where the oil transfer passage to the head is located, and they rarely leak there. Most head gasket failures are at the cylinder seal. I'm not sure of the head oil transfer passage location on the 103 engine, but I suspect it is up front, since the oil pump is towards the front.

A more likely source of your leak might be the back of the cam cover gasket. My 2.6 began to leak there a few years ago, so I changed it. Suggest you clean the engine thoroughly in the vicinity of the leak and monitor it closely until you are absolutely certain of the source.

Swapping the cam cover gasket is a no-brainer and cheap compare to the cost of a complete cylinder head refresh!

Duke

It sure is a lot of work and money to solve an oil leak on a car with only 86K miles, but these engines are notorious for oil leaking externally at the right rear (passenger side) corner of the head gasket. The original gaskets had a poor design. The new gaskets are redesigned with copper inserts that prevent the gasket from failing.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

I don't have too much tech data on the 103 engine, but I do have an oil system schematic for the 102 engine in my "Model Year 1984" D-B manual.

Indeed, the oil transfer passage to the head is at the right rear of the block, so an oil leak at the head/block interface in this area would make the head gasket suspect, but if the leak is minor it could be left alone until the cylinder seal goes or coolant begins to leak. Minor oil leaks are a nuisance, but don't have much potential for consequential damage.

I had a similar problem many years ago on my '72 Vega GT. Oil seepage began at the right front of the block/head interface where the oil transfer passage to the head resides, and since the car was still on warranty I had the dealer replace the head gasket, and the problem did not reoccur.

The shop in San Clemente, CA that replaced the valve guides in my Cosworth Vega head last year (the owner also has a CV and just finished a complete rebuild) primarily works on Merc and BMW heads and has a steady flow of business. He says the guides wear fairly quickly because they are relatively short.

If one were to pull the head to change the gasket, it would probably be a good idea to go ahead and have the head completely refreshed to include new valve guides, valves (if necessary due to stem wear or seat condition) and valve seals along with a reseat of the valves, pressure test, and head surface check. Even if a head measures flat most shops like to take a .005" cut to ensure that all the old gasket is removed and the head surface is dead level. That virtually guarantees a good seal as long as the head gasket design is okay.

With a fresh head and a good gasket, the engine should run at least another 100K miles without major attention.

Duke



Duke

Actually, 1990-1992 300CE's have an M104 engine (104.980), not M103. It is a 3.0 liter engine with dual overhead cams, and is an early version of the later 3.2 liter M104 engine (104.992), that also benefited from variable valve timing, as well as all electronic fuel injection.

For the record, 1993 300CE's actually have the 3.2 liter M104 engine found in 1994-1995 E320's (and 1996-1997 W210 E320's). They just didn't change the badge.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Just a note regarding valve guides on these engines, the M104 head design has minimal vave stem/quide side force [ cam-valve swipe] . Mercedes seems to have solved the common M103 valve guide problems with this far superior design and it is not unusual to see them still tight into the 200K figures.

The 104s have a very strong top end....along with some pretty good breath....I would normally recommend to do them on M103 engines just because the 103s have a lot of swipe [side] force compared to engines like the 104s.

So they are just more prone to wear by valve train design....

Having said that, I still redo the valve guides and valve seals simply because the head is off the car and they are cheap.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

The oil leak has been addressed by applying a SILICONE BEAD around the oil and coolant passages on the head gasket. If the head is FLAT, have a clean-up cut done on it. BETTER YET . . . If you have a machine shop in your area that surfaces heads with a belt sander . . . do that . . . If the car doesn't smoke at start-up and the COMPRESSION, POWER and IDLE are OK . . . you can get away with just doing a HEAD GASKET . . .