Originally Posted by barry12345

Cars are disgarded for reasons. This could be why that one in the wreckers was.. If you are going to persist. Go back to the car to see if there is anyway to contact the last owner. Some people leave papers in cars they send in and perhaps even licence plates in certain states.

Personally I suspect the cracks in these heads act like one way valves. Under high combustion pressures they admit pressure to the coolant passages. Under low pressure they no longer leak.

This is kind of verified by 603 engines with cracked heats still have coolant system pressure the next morning as a test. Logically to me if they also leaked at low pressure. There would be no retained pressure in the coolant system the next day. The pressure input could be very high also but any accumulating above the radiator cap limit. Would just be relieved by it.

I am not suggesting what you should do. Yet if I lived in your part of the country myself I would look for a newer head. Primarily because the odds of finding one are very high there compared to my region. Those cracks may also be a good reason for an engine to run hot.

Also other members could comment. We have quite a few members that have changed cracked 603 heads. Was there coolant in those cylinders that had the cylinders with the cracks in their heads? If my thoughts are right in many perhaps none was observed.

Since of course I only have limited abilities and experience. I am almost positive that you can find a rebuilder of Mercedes heads in your general area. The most famous one is even in your state I believe.

My suspicion is they will tell you that any cracks found of your type existing in that number fourteen head. They probably do not even bother testing it. Simply because it is what it is. A number fourteen head that has cracks. In addition all cracks of that type you have always create issues they found.

There are heads with real obvious cracks like the early Volkswagon water cooled diesel engines. The first one I pulled scared me . Until I found out they were normal unless really wide. Every cylinder had them as well. Yet they never caused me a problem. We pulled a lot of those heads to change failing head gaskets.

Plus if by some odd chance my thoughts are correct. They may have found out they do not leak test in the conventional way a long time ago. Again just a suspicion of mine. Unless the cracks really open up. The hot water expands the alloy head of course. It is just not restrained when it cools down like it would be to some extent when mounted on the block.


Also remember that an alloy head on a cast iron block has movement in relation to the cast iron block. So in service this can actually manipulate the cracks slightly. Yes it slides on the head gasket but the forces are still substantial on the casting. Over the years I have thought there are perhaps many contributors to the high failure rate of these heads anyways. Just food for thought.