OM603.970 Engine question - PeachParts Mercedes-Benz Forum

635CSi · #1 02-02-2015, 07:14 PM

So it turns out that my 1990 350SDL is burning a lot of oil and piston noise, after tearing the engine down it turns out I have a very slightly bent rods in cylinder 1 and 2 and damaged cylinder walls. I know I can get a 603.96X engine but I really do like the 350 engine... so much so I've already got all new internals coming in, the block will get new cylinder liners and is at the machine shop right now. the head is getting machined and rebuilt and the crankshaft is getting some work done as well.

Once the engine is all assembled and ready to be started, what is the break-in procedure for this engine?

Cheers

vstech · #2 02-02-2015, 07:43 PM

I would keep rpm below 3000 for the first 500 miles. Then change the oil no synthetic still then drive smoothly next 1000 miles then change it again.

rob300SD · #3 02-02-2015, 07:48 PM

If it was a high reving engine I'd say don't take it up past 6000 rpm for the first 500 miles. But I don't think it's an issue with the diesel. Just drive it. Varying city driving. Not just at one rpm on the highway for instance.

Change the oil and filter after 3000 miles. Then go 5000 between changes. Some people might say to change it sooner the first time, but the filter will pick up the tiny amount of any metal that might make it into the oil. (You can change it more often, definately won't hurt anything)

PS:Not posting this to disagree with vstech. He posted before I did and I didn't even see what he had written.

rob300SD · #4 02-02-2015, 07:49 PM

I agree, no synthetic. It won't break in well with synthetic, or it may take 20,000 miles to break in.

635CSi · #5 02-06-2015, 05:04 PM

Great, thanks guys

Sveinn · #6 03-01-2015, 05:44 PM

Sorry to say, but the 350 diesel engine does not use piston liners, like the 300. You have to bore out the block & get a whole set of oversized pistons.

I would have rebuilt my 350, but I couldn't see paying more for a set of pistons, than I paid for the car. I put a 300 engine in it.

compu_85 · #7 03-01-2015, 06:03 PM

There are liners available for the 350, but they are quite expensive.

-J

sixto · #8 03-01-2015, 09:29 PM

How does the cost of what you're doing compare with a $6400 short block from Metric Motors?

If money's no object, how about a set of custom rods from Carrillo or whoever makes high end rods these days?

Sixto
MB-less

mytmousemalibu · #9 03-01-2015, 11:50 PM

Just a little break in tip, get you some really powerful rare earth magnets, hard drive magnets work quite well and are cheap or free. clamp a couple around the oil filter housing. You would be surprised at what a good powerful magnet can do to pull ferrous particles from the oil. It works real well on spin-on filters, every one I had cut open had a big dark patch of ferrous grime where the magnet was. Its like free filtration that works endlessly. Works good on steel bottom oil pans too.

635CSi · #10 03-02-2015, 07:19 AM

Quote:

Originally Posted by sixto

How does the cost of what you're doing compare with a $6400 short block from Metric Motors?

If money's no object, how about a set of custom rods from Carrillo or whoever makes high end rods these days?

Sixto
MB-less

The cost in parts and machining has worked out to 5000.00 Canadian dollars. The biggest issue was time frame to get custom built rods. When looking at the new rods there's a huge difference in the thickness, I'll post pictures as soon as I get back from Vancouver.

635CSi · #11 03-02-2015, 07:21 AM

Quote:

Originally Posted by compu_85

There are liners available for the 350, but they are quite expensive.

-J

Liners weren't too expensive, 81.00 Canadian taxes in.

Maxbumpo · #12 03-02-2015, 03:02 PM

I have heard that swapping in a later OM606 turbo is a pretty good way to go. Keep your mechanical injection pump, get a more powerful turbo-diesel with intercooler.