yup. I have 2 617's with cracked heads from driving without coolant I'd guess...

A 123 diesel was in my indy's shop late last year with what they finally decided was a cracked head from driving with little or no coolant. The driver simply ignored the gauge as long as the engine kept running. The mechanic said it actually ran fairly well, considering. Last I heard they were shopping for a good used head.

Jeremy

I found a 15 in a JY years back, it was on a 3L motor (in an '86) if that tells you anything. Sold that off as I bought a fully refreshed 17 on the board with camshaft, new lifters, new springs, new injectors, etc.

Potentially I may have a few pictures of it still, if anyone cares I will look. I think it had the 'straight' injection still.

#15 head info
 

I bought an intact #15 head as a core to rebuild and replace my cracked #14. It appeared not to have been machined before it got to me. It had the collars with the splines and the newer angled prechambers. It didn't have the coolant passage near the timing chain filled in. The machinist put my old prechambers in this head so I could use my just-rebuilt old-style injectors. He has a long background machining & building Mercedes heads at a dealer, but had not put straight prechambers in a #15+ revised head before. They dropped in fine and the prechamber protrusion into the combustion chamber was within spec, but they all still leaked like crazy, which he says he has seen many times. He says he has addressed the problem before by using some kind of locking sealant on the prechamber mating surfaces and on the locking collar threads.

I haven't looked at all the prechamber leaking threads yet, so I don't know if refinishing the prechamber bore and/or adding a shim to create a better sealing surface is a better solution.