Have a 89 300E that has a coolant leak at the rear passenger side of engine that appears to be between head and block so I'm assuming that head gasket must be defective. After reading the crappy Haynes manual I have, it appears as though headgasket replacement is straightforward on this vehicle. Any comments or advice??

Earl
Find a experience tech do it for you
by the way how many miles on the vehicle ??
you may do the valve job at the same time to save some $$$$ on labor.
may should you have update head gasket set...
replace coolant by pass hose btw head and water pump. Hope this Help.

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MB STARS Master Guild Technician,12 years MB tech
5 years independent shop owner

On the drivers side of the head at the rear is the fitting that the coolant return hose from the heater connects to. This fitting has an o-ring that will cause a leak that can be hard to find. Have your tech check it out first!!

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MERCEDES BENZ MASTER GUILD TECHNICIAN
ASE MASTER TECHNICIAN
27 YEARS M.B. TECH

Thanks for the tip to check the coolant return. I will replace the seal there before proceeding. Having spent nearly 10 years of my life building formula ford and super vee engines I am not the least bit intimidated by replacing the headgasket on this car myself. The last headgasket I replaced on a personal car was a BMW with the 2.5 M50 engine which is more complex (dual cams/variable timing) than the MB M103. That car went 28,000 miles (with zero problems) after I replaced gasket before I sold it so I think that I obviously didn't screw it up. Also have the necessary tools, torque wrenches, torque angle gauges, etc. So, back to my original question, is there any thing abnormal or exceptional about replacing the headgasket on this engine?

M103 head gasket replacement should like a piece cake to you.
after reomve timing chain uper cover there is a metal pin inside the plastic chain rail
have to remove it first befor remove head
(special tool) if you don't have you can use
a socket and a bolt to force it out (don't damage the plastic rail)when reinstall uper
timing chain cover becareful the cam shaft seal and the u seal.
also chain tensioner must dissembled befor reinstall to do this by push the pressur pin (with detent spring) out of thesioner housing on one direction only....install put the tensioner housing back in cylinser head first then insert the pin(with detent spring)in to housing then the pressur spring and the cap with seal ring back.
hope this help.


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MB STARS Master Guild Technician,12 years MB tech
5 years independent shop owner


[This message has been edited by MB STARS (edited 06-24-99).]