Much has been said about oil usage in M103 engines. In my case, it appears to be coming from around the camshaft seal. While picking up some parts at my local MB dealership last weekend, I was told this is all too common on these engines. The parts counter employee indicated that a special tool was required to drive in the new cam seal. Do I REALLY need a special tool to replace an M103 cam seal? Are there any other special tools required? Thanks for your time.

Mike Murrell
'91 300-SEL
Boerne Texas

A special tool is required if you are only replacing the seal and not resealing the cam cover itself. If you take the cam cover off you can tap the cam seal into the cover with just a hammer. Most of the time it is the 'U' seal at the bottom of the cam cover that is doing most of the leaking. In that case you should get a tube of the MB Black sealer for the edge of the 'U' seal that butts up against the head. The tricky part is installing the cam cover over the top of the 'U' seal and without disturbing the cam seal. You may be better off leaving this for your MB mechanic.... But if you do tackle the job yourself, then be patient, and if it leaks the first time, then learn from your mistake and try again.

Now you mentioned oil consumption. That is most likely NOT from the oil leak at the cam cover, but rather from the valve seals. Is there a deposit of carbon from the spark plugs?? I saw a bad case of carbon on the plugs just yesterday at work, and the customer declined the repairs.

Eithe rway, Good luck!

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Metricman - thanks for the info. MB made the 300-SEL from 1988 -> 1991. According to a couple of other sources, the valve seal/guide problem existed on '88-'89 models. 1990-1991 models supposedly came with new/improved guides/seals. Mine is a '91 model. The plugs have a tannish color after 10,000 miles of driving...no indication at all of oil getting past the guides/seals/piston rings/anything of that nature. When I change oil, I pull the large plastic encapsulation cover from the bottom. There's a spot on it where oil is landing that's pretty much underneath the distributor area. Regards.

Mike Murrell
'91 300-SEL
Boerne Texas

If the exhaust guides are the ones that are leaking, it will not show up on the plugs. On the exhaust stroke, it just blows it by.

The tool is not 100% needed, but I always use them to insure a good job. (Without, you can roll the seal.


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Benzmac:
Donnie Drummonds
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The can cover is relatively easy to take off, if you put in the new seal and push the cover on while turning the engine with a wrench on the crankshaft you can avoid damaging the seal. With some help this is not that difficult (a can of beer is cheaper than a special tool).