Hi Guys again!
I've decided to go forward and get my OM636 rebuilt. Now the hard part. I don't know anyone . Do any of you know of a quality diesel engine engine rebuilder? Preferably on the west coast , I live near Seattle Wa, Metric motors in Ca, said no, Reinvent the wheel in southern Oregon said no.
Any help appreciated! thanks Angus

This is our vintage Mercedes part of the forum. Someone there my know more.

Vintage Mercedes Forum - PeachParts Mercedes-Benz Forum

There is also another forum benzworld.org.

Before I correct all of the below these are spacs for an om636 Diesel engine. The specs for an OM621 are different.

As it happens, I have a real Mercedes repair manual on the OM636, 621.

Looking up some specs. You will have to do any conversion math.
1 kiogarm force per square centimetner = 14.22 psi.


Compression Taken at 200-250 rpms

normal 22-23 kg/square centimeter (312-327.137 psi is normal compression)

Lowest limit 17kg/square centimeter (241.79 psi is the lowest allowable compression)

Practical compression. It is a normal winter cold day (not unusually cold) and using the glow plugs normally my engine starts fine. Nothing to worry about there.
The same situation and you have a lot of trouble starting and your glow plug system is working perfectly. You have a compression issue or a valve adjustment issue effecting your compression.

The above focuses only on compressing issues. Hard starting can also be from fuel injection pump timing Ing and poorly atomizing injectors.

Permissible hot oil pressure is 2-8 kg/square centimeter. (28.4467-113.787 psi is a normal hot oil pressure.

If I remember from your other post your compression and oil pressure seem to be normal. Meaning no real need to overhaul the engine.

What I did not see is there is normally a spec as to what differences in compression pressure area allowed. As an example, you would not want to have one cylinder down at 300 psi while the others are up at 327 psi. That could be an indication of a piston ring/groove/cylinder issue or some leaking valves seats.

General engine overhaul stuff. You don't really know what can be fixed till you take the engine apart and measure and compare that to the factory tolerances.

As an example, you cannot tell if you can simply go in an install new piston ring. Because you don't know if the ring grooves on the poisons are worn out and you don't know if the cylinders are too oversized or out of round for new piston rings.

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84 300D, 82 Volvo 244Gl Diesel

it looks to me as if the engine is in good running condition.

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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.

Besides no. Where any reasons given for them not wanting to rebuild that engine model? Mercedes have any older rebuilt short or long blocks left?

If parts are still available as needed there have to be very competent rebuilders out there. A little historical research might also turn up what to expect for parts needed and some estimates of parts cost plus availability.

Perhaps the Mercedes center in California could suggest who they would use. They do general restorations so they have to have someplace they use.. Plus a general indication of expected cost.

I would also Like to see a description of why you think it needs a rebuild. As there are various issues that can be deceptive. The integrity of the engine itself has to be tested usually. Compression and leak down. Those older injection pumps for example do have different issues than the later ones. Plus there may be routes that oil can be going where it should not be. Head gasket rotten with age.

Thank you guys for your input! I'm thinking I'm ok, It does have some pretty bad oil leaks that I'll be fixing. I'll see if that helps. OK thanks again! Angus

I’d be interested as to why these companies say no. I’d suspect that parts availability is the concern.

I can’t imagine that rebuilding one of these is that much different from an antique tractor, wwII truck, etc. stuff that folks would have interest in rebuilding.

I’d probably look for someone that works on old tractors or old collector cars.

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)