Hello everyone!

I have just started into the world of the Mercedes diesels, and am currently working to figure out what exactly to do. I just picked up a used OM603.970, unfortunately it is the original block. Unknown mileage as the guy I bought it from bought it from someone else, though says he will see about contacting the other guy, who bought a project truck with the engine in it. Of course I can feel plenty comfortable in knowing this will go great....since both of them thought it was an OM606, which the guy I bought from I can at least give some relief to as he probably knew about as much about these engines as I did 3 months ago which was just that they existed.

All I know is that it was running, IP seems to have been rebuilt, or at least noticeably clean compared the engine, as it was described as a "performance fuel injection pump," and was daily driven for 2 years before being pulled for a project truck.

Here is what I know for sure though, turbo will need to be replaced, though was part of the plan anyway for my project which I need a lot of research to learn about turbos as I currently know jack squat about them. Oil pan had been removed at some point since they used gasket sealer on it, hopefully I can find out something about that from the previous owner.

I imagine I probably should have just passed on it overall and waited to have the cash to afford a whole donor car for a OM606 turbo, which of course being stuck to 2 year models for my options makes slightly fun when I have other financial obligations at the moment that make an immediate $3-6k investment, depending on mileage of the donor, slightly difficult. Hopefully if I do lose on this, I only end out a few hundred dollars, but do at least get to figure out for my setup in the meantime for my swap, which is going into my 1992 Ford Bronco. Main power goals are more towards torque, which gets difficult to find good answers on, but I'm only looking to beat the old 5.0 that will be coming out of my Bronco, at least until I can source a heavier duty transmission as the current one is only rated (from what little info I can find) for an input of 330 ft/lbs. Of course the other reason I want to go diesel is for hopefully better fuel economy. Currently running about 11.5-12mpg isn't necessarily too great, plus the "typical" diesel options aren't too appealing in availability or cost due to their popularity, and who wants to be running around with an American diesel anyways?

So, if anyone has any advice for routes to take with the OM603.970, or can point me in the right direction for sources of information, it will all be appreciated.

So as a minor update on info about the engine. The car had about 200,000 miles on it, so probably safe to say at this point, without disassembly for now since this is going to be a slow process, that it is "safe" from suffering from rod bender status.

Read Turbochargers by Hugh MacInnes
https://ia800104.us.archive.org/4/items/TurbochargersHughMacInnes/Turbochargers%20%28Hugh%20MacInnes%29_text.pdf


just note that some info is a little outdated, and we use wastegates commonly now instead of bigger A/R turbine housings

I've seen stock OM603 turbo engine withstand 30psi of boost from a borg 200 series turbo and a 7.5mm pump, if it bends rods, it is due to a hydrolock.

You will need headstuds and a modified OM606 headgasket for any serious performance use. ARP can sell you studs, but you'll need hardened washers to get the right height, most of their 10mm studs are a bit to long or too short IIRC. A small t3 / t4 hybird turbo would be perfect for the om603, a .48 turbine hsuing with a stage 3 wheel and the biggest s60 t3 compressor or the smallest 60 trim t04e etc with cover. use the small t3 hotside, the integrated mustang and ford turbo outlets are nice, available in 3 inch outlet, easy to use with a stock style spring loaded gate, and cheap as sin on amazon etc.