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- Jonathan, You have a great website here. Many of us Mercedes drivers often don't
know where to turn when major work is needed and or suggested by our friendly dealers.
Nice to know there is a legitimate source for info. Which leads me to my question. I
recently purchased a 1989 300E with 78,000 verified miles on the car. It is a very well
maintained car with all service records. I noticed a small puddle under the car and have
traced the source to what appears to be a head gasket leak at the rear of the head. The
coolant is clear ( no oil in it ) and the oil is clean and shows no foam. What kind of
money am I looking at to have the head gasket replaced? Is it possible that it is a simple
matter of retorquing the head? Any other issues I should worry about? The car is under
warranty ( as good as a used car warranty can be) so I'd like to get it addressed ASAP.
Many thanks for your help and insight. Steve
- Steve, This is a common problem with the 300E 86-91. The fact that you have
no foam in the coolant is a good sign. The Mercedes Benz coolant when left
in an engine too long becomes very acidic and eats the head gasket in one of
the water jackets and because oil runs at a higher pressure than coolant the
coolant foams. Watch the reservoir for oil. The oil leakage is another
problem all together and a common one to boot. The main oil feed hole for
the head is in the right rear corner by the Trans dip stick tube. When the
gasket ages the oil seeps out, really not a big deal unless you start to
smell the oil or see it on the floor. If the oil level does not drop between
changes enough to turn on the light then you might consider living with it.
On the other hand if you do change the gasket it will not only solve the oil
leak at the back of the head, you will get a new u-seal at the front of the
head and guarantee yourself that the eventual entrance of coolant in the oil
will be postponed for many years. Change the coolant to green in a 50/50
mixture with distilled water and get the gasket changed. It should not cost
you more than 900.00 in any case. You might consider a new timing chain at
the same time. JON
- Jon, Thanks so much for the response. My note was not clear in that the leak that
I have identified is not oil, but antifreeze. Does that change your
diagnosis or create any other concerns? I also just learned that the head gasket
was recently changed ( by a Mercedes dealer) . Would this be as simple as
retightening the head? One last question, how long should I expect a gasket to
last ? Thanks again for your help and interest. Steve
- Steve, if the dealer just put a new head gasket on and there is a coolant
leak it is almost impossible for it to be the gasket. I have been thinking
about this, it seems to me it is either the coolant hose at the back of the
head by the oil filter or the water pump. There is a bracket that the hose
connects to, the bracket is then held into the head by two Allen bolts with
an o-ring on the shaft where it goes into the head. This o-ring leaks alot,
and unless it was replaced it could leak. If the MB dealer had one of the
apprentice teenager mechanics do the head gasket it could have been torqued
down wrong and leak but I doubt it. Let me know what happens . JON
- Jon, You were right. The culprit was the O-ring. I really appreciate your
help and insight. Any plans to open a shop in Portland Maine???? Thanks again.
Steve
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