Hi everyone,this is a great site here & you guys really know your Mercedes.My prob is I have a 190,000 mile 1989 300e 3.0l with an oil leak.About 1 yr ago I resealed the front timing chain cover & it still seems fine but now the head gasket is leaking in the rear & possibly the front also but mostly the rear.How hard is this going to be,Im sure I can handle it , I work on Audi's for a living & ive done worse jobs. Is this common & is there anything special I need to do or any tricks that can make this go as smooth as possible & are the front timing chain covers prone to warpage?Oh one last thing would anyone know the head bolt torque?Thanks again guys.

 

Franco, I also have a 300 E and the rear of the engine leaks at the head gasket. My mechanic says that most MB 6 cylinders leak there at some point. I experimented with different weights oil and some trusted additives and I have mine just about stopped. I don't think just the gasket change is much of a job but I hear that you should change out valve guide seals and have the head reworked which gets expensive. I didn't believe it at first but try different weights of oil. It worked for me.

 

If you've never done one of these before, The main things to look out for are. Make sure the head bolt lengths are within spec, and the timing chain tensioners can be a bit tricky. And make sure you keep everything clean during assembly. (of course that goes with any job)

Cylinder Head Bolts (Cold)
Step 1 ......................................... 41ft lbs (55NM)
Step 2 ........................ Angle Tighten 90 Degrees
Step 3 ........................ Angle Tighten 90 Degrees

NOTE:
Upon removal of the cylinder head, it is possible for engine oil or coolant to flow into the head bolt holes, filling the area of the bolt threads.
During reinstallation and tightening of the cylinder head bolt, this oil or coolant can get highly compressed by the threaded end. It is possible that the resulting pressure of the liquids in the bolt hole could cause the engine block to crack. So prior to the installation of the cylinder head, all fluids and dirt must be removed from the bolt holes. I usually use compressed air.

Hope this helps,
Cheers

 

I'm just finishing up the same job today on my Dad's 300E. Pretty common that these 6 cylinder engines have head gasket problems when they get up there in milage. I torqued my heads down to 70Nm (45FT/LBS) and waited 10 minutes, gave them a 90 degree turn, waited an hour and gave it another 90. I don't have the liberty of working in a shop here, so I'm inside right now due to rain waiting for it to clear up so I can put my cam back in and torque down the exhaust bolts and such and button everything back up, and of course run a few cleansers through the cooling system to clean out the rest of the oil that was shot through the cooling system when the head gasket failed. Anyway, good luck!