Found small crack in OM603 head

[jorgenbg]

Hi,

I bought an 1987 OM603.96 from a California 1987 300SDL and put it into my 1992 350GD. I had to pull out the engine to change the oilpan and some other stuff, and I thought the head gasket was leaking a little bit.(Water just above the waterpump, and oil by sylinder #1 and #2.)

So I decided to change the head gasket while the engine was out. I have been driving the car with the engine for almost a year without any mechanical problems. I went to this small machineshop to have the head checked. He told me the head looked good and probably never been overheated. I think the head nr is #20. But he found a small crack by one of the prechambers. It's about 1/5 of an inch long and goes straight out. Not to a valve. I did not notice unatural pressure in the cooling system before. This guy told me that I should take a "chance" and use the cracked head.

What do you think? I don't know much about these things.. The head from my 350 engine is also cracked. It has one crack from the prechamber and to the valve. The 350 head is the same number, only it's a #21.

[aklim]

Check with a local diesel truck shop. They might be able to weld it up or you might end up with a paperweight.

[Brian Carlton]

If the crack goes from the prechamber and does not enter the cooling system in any way, I'd be inclined to use the head without repair. The option of welding the crack introduces a whole new level of risk. The option of replacing the head introduces a whole new level of cost.

[Rich300TDMBZ]

You have the #20 and #21 heads, and they cracked? Humm, this brings a level of concern among owners of cars with the 603 heads. I thought these new heads, compared to the #14, rarely cracked. Does your #21 head cracked because of overheating?

[rrgrassi]

I have learned to never used a cracked anything. the new stresses caused by retorquing, etc can cause the crack to expand, and that usually happens when you are 100 miles from home, worst type of weather, etc. Do not chance it. Welding can work, but the chances of the weld cracking, or new cracks developing are increased due to the heat introduced by welding. Cast things like blocks and heads usually do not show good results from welding. Best thing to do is find a good one in a wrecking yard.

[Rich300TDMBZ]

QUOTE:Best thing to do is find one in a wrecking yard.

Are you kidding me? 603 heads especially the ones above #14 are very hard to come by. Let me know if you have one for sale.

[rrgrassi]

I wish I had one for sale.

I'm still looking for a MB diesel to drive. I do have a line on a 300d and a 300cd.

If the heads are very scarce, then you will have to do a nationwide search. If you have a local shop that you trust and are friendly with, they might be able to have a national database searched for you. I found a transmission for my truck that way. Turns out the automatic my 4x4 has is the "rare" one.

I am restoring a piece of railroad equipment, and have the same problem finding parts. When I do they are either too expensive, or someone else beat me to it. Ebay has not been a good source either.

[dieseldiehard]

The head rebuilder that does a lot of work for Metric Motors has tried welding cracked 603 heads - something like three out of four of them failed shortly after being put back on engines. His policy is never to try that again because he doesn't want to steer people into thinking its a reliable solution. It isn't reliable!

My "Data Base" Parts suppliers experience, while looking for a 603 head, is here:
By it so I dont 87 300d $400

[jorgenbg]

Does your #21 head cracked because of overheating?

I dont know, but the head was not even at all. I bought the car last year with the broken engine. But the 350 in a G-class is well known of overheating. Thats why I thought the 300 would be better. Mercedes never fitted the 300TD into the G-class.

I found used heads from about 800 dollars.. Have todo some more checking tomorrow. Thanks for the advice..

[blueranger]

you did well by taking it to a machine shop... The guy at the machine shop
has handled thousands of heads so I would not dismiss his advise so readaly.

It is true there are folks that weld heads with good results. They preasure test afterwards and normally you would use some one with years of experience. I would seriously consider this option.

The actually instructions on turbos say to exspect cracks and go ahead and resuese if the crack is not in a certian area or past a certian length.

There is a new thing out called alumaoloy. It looks like a welding rod but it melts with a torch and its used with cast metal....

What I think I would do is this: I would drill each end of the crack to stop it from expanding. Then I would enlarge the crack. Then I would use a torch and fill it with this alumaoloy. I would sand it flat and put it on and see if it holds preasure. Your risk is a new head gasket and redoing the work...

good luck

[dieseldiehard]

Originally Posted by jorgenbg

I dont know, but the head was not even at all. I bought the car last year with the broken engine. But the 350 in a G-class is well known of overheating. Thats why I thought the 300 would be better. Mercedes never fitted the 300TD into the G-class.

I found used heads from about 800 dollars.. Have todo some more checking tomorrow. Thanks for the advice..

603.xxx cylinder heads from the '86 - '87 300T/TD are known for cracking. Mostly the original #14 caasting but even a #20 head failed for a crack
But most people won't tell you or don't know that many of the aluminum heads (also used in gass engines!) have failed because of leaking head gaskets, or the engines were overheating and people didn't promptly replace their radiator or even bother to chem flush the existing ones, or the radiator plastic necks cracked and the coolant ran out, or the water pump impellers were eaten up by corrosion like the one GSXR pictured in a thread on his many experiences with these engines. ANd some failed for ruptured heater hoses. Anything that causes loss of pressure will contribute to overheating. Then there is the Nasty Trap Oxidizer. My belief is that this also contributed to head failure, that is a known cause for overheating. No one connects this item to head failures but it there and is a known factor in the '87 diesels.

There are lots of #14 heads still in service at over 250K miles (I can attest to personally owning 2 of them) and more than few have over 350K miles and are still running strong! If you get a good one its likely to be ok as long as it wasn't grossly overheated. If you find one that is still relatively flat and passes a pressure check it will probably work out fine. If it is warped serioulsy I would be cautious and I would never buy a cracked one and try to weld it (even if it was free!)

[Hit Man X]

Heck, I bought an entire motor for an updated vac pump and a No 18 head.

FWIW - you can see the mileage of my SDL in my sig with the original No 14 head. Hopefully I'll never need that No 18