Well its about time I tackled my head gasket problem....
Car is a Euro '85 W126.037 with M117.963 5.0 engine. 135k miles
I bought the car very cheaply about 18 months ago after it had been overheated. When I first got it, the quantity of steam from the tips was crazy. I retorqued all of the cylinder head bolts to spec, and threw in some bars leaks for good measure, flushed the brown sludge oil out, and i've been driving it ever since! The car does still use water, around a quart every couple of weeks, but the oil remains clean.

Anyway, down to business.... Whats the likelyhood that just one head gasket needs changing, and how do I tell? use a compression tester? I dont think I can read the plugs, I run propane, so no soot.
I'll be doing the work myself, so dont really want to do whats un necessary.
What else should I think about changing while i'm doing the job? Valve seals? I read that the chain guides should be changed... the chain is quiet at the moment.
I know that i'd have to get the head resurfaced.
I've done head gaskets and rebuilt heads before, but only on pushrod engines, so the removal of the timing chain to get the heads off is a bit daunting to me.

Hope someone can point me in the right direction...

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Ben

'85 500 SEL
'85 928S2
'88 560 SEC
'90 750i

W/O question both heads should come off. Chances are both will have Significant amounts of corrosion on them that will need to be tig welded back up and decked back to spec. Valve guides/seats/seals etc need to be tended to as well. Any timing chain/tensioner and especially the upper guides that are 21 years old Need to be changed..as do the oil line clips for the oil feed tube on top of the cam towers.

Jonathan

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Blue Ridge Mercedes
Jonathan Hodgman
http://www.blueridgemb.com/
Enthusiast Service, Restoration & Tuning.
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Specializing in all pre and post merger AMG's including Hammers and DOHC M117 engines.
Mercedes Repair Atlanta

One way you might identify the problem head would be to pressure test the cooling system overnight or repeatedly with the sparkplugs out. Then crank over the motor and look for coolant coming from a cylinder.

Then you should do both heads as it is 2/3 of the work to do just one head and they both fought in the same war.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

I thought as much... I 'll probably end up doing both heads. What I didnt think i'd have to think about was welding up the corrosion! I did an aluminium head on a different car, and that didnt have any noticable pitting, and after it was decked it was spotless. I guess I wont know until I pull the heads.
Whats the likelyhood of having to helicoil the head bolt orifices in the block?

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Ben

'85 500 SEL
'85 928S2
'88 560 SEC
'90 750i

it could happen. i havent heard of mb head bolts doing that though.

always a possibility with aluminum though.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.