I recently purchased a used OM603 head via ebay (with the help of gsxr). It was advertised as "excellent working condition." The casting number had been ground off (strangely enough), but the oil and coolant passages suggest it is a #22 head. I received the head yesterday and plan to take it to a shop to have it inspected for cracks and have its flatness measured. I will share those results as they come available. But upon arrival, there is a significant other concern which has come up.

The head has major erosion at locations where it meets coolant passages in the block. Some of the erosion is deep, but narrow. I measured one to be 0.12" deep (1/8"). Some of the erosion is wide, but shallow. Some are stained green, so I suspect this is due to use of green coolant by the prior owner. It appears to have occurred in places where a coolant passage in the block meets the head, but does not continue into the head. I have no idea why they are designed this way. In looking at pictures of the head gaskets, it appears that they have holes at these locations, but for reasons which don't seem clear since the coolant has no where to go (but erode the aluminum near the hole).

I have attached some pictures of the problem areas. The first photo shows the general head condition. The problem areas are the oblong larger discolored areas which are vaguely triangular. The second photo zooms in on the deep, narrow damage. It is hard to tell it is even there until you see it in person. The third photo shows the widest erosion area. I think the coolant got behind the head gasket at this location, since the damage is wider here than the head gasket hole. The 4th photo shows where the erosion is closest to the cylinder. It is hard to see, but the erosion is within 0.03" of where the metal band of the head gasket used to sit.

Most of these are too deep to machine off. You can only remove 0.02" from a 603 head, so eliminating a 0.12" deep eroded spot isn't possible. What do you all think? Should I send it back (seller has a 30 day warranty, but I have to pay shipping)? Would you use this head on your car? Is there an easy fix like high temp RTV to keep any future coolant (zerex g-05 of course) from getting to these spots. If it requires welding, I am not going to bother (or risk damage to the rest of the head). Maybe with proper coolant, no more damage would occur, but who knows.

My #14 head is not showing signs of cracks, but you never know what tomorrow holds. I bought this used head to be a permanent solution. But with these erosion problems, I am not sure I will have any confidence in it. Any suggestions on how to proceed? This was a big purchase for me, so I am a little disappointed in finding this significant damage.

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).