was just wondering which years had the problem with head cracks. i know my 89 has the upgraded heads. im interested in an 86, and was wondering if that year had the crack prone heads. thanks!

 

Crackheads?

 

None. You are confusing some other engine with Porsche M28's.

 

I have never heard of it being a problem on any MY 928, can someone elaborate on whether or not the problem does/did exist and which MY?

 

89s were the first to have head revision because of a cracking that happened.

 

Any pre 89 would answer your question. Cracked heads are rare but I have seen a few on high HP cars.

This is why 89+ heads are worth a bit more than "regular" heads. Also why I purchased that burnt up 89 a few years ago. The heads alone are worth what I paid for the car

 

I think they were all pot heads

 

I bought an '83 Euro some years back that had a cracked head. Used in multiple open road races after rebuilding the engine and replacing the head. Still running fine ...

 

I have never had a head crack, and have seldom heard of such a thing. I've owned many 928's of all years. You will not likely suffer cracked heads ever, you're far more likely to suffer oil starvation, rod bearing failure, broken rings, broken timing belt, failed water pump, radiator failure, heater valve failure, steering rack failure etc etc.

 

Been awhile Paul ... so you never came up here huh

 

A local rennlister, who has an 87 or 88, can't remember, had just replaced a cracked head. He was all the way out in Washington(state) from Columbus when it happened. Let's just say, it wasn't a cheap tow bill....

He took the head to a machine shop and they did what they do, he replaced the head and it STILL leaked.

He ended up needing to buy a new head from 928intl. This proved to be successful. Shark was down 9 months...ugh...

 

Brad, why didn't he contact us?

 

Good question...he might not have had 'the list' with him. He was attending the 928 /Porsche event back in August of 06 in that area...I can't remember the event name though...

 

Sounds like he was here in Portland for the 2006 Porsche Parade.

 

The '87/'88 models suffered from the head cracking problem the most, although we've seen cracked heads in the '85/'86 models. The cracks occur in the radius where the head bolt washers sit, usually on the center two bolt holes. Very hard to see and very hard to figure out where the water is coming from....even with the heads off. On the early heads, the head bolt washer surface is machined down into the head and right where the flat surface for the washer curves upward (the above mentioned radius) the cracks form. Porsche solved this issue by raising this surface up by about 5/8" or so, which eliminated the need to cut into the surface of the head for the washer.

The water leakage from the cracks is very minimal and hard to figure out. Brian Donaldson had two cracked heads on an engine we put together for him. Took quite some time to figure out (over a year, for sure) where the water was going to. We knew the car lost water, but finding out where it went was really tough. It never lost enough water to do anything wierd to the oil, until the very end, when the water loss became severe enough to see in the oil hoses around his supercharger. You out there Brian?

It is common enough that we try to use the later heads on all our big engines. It would suck to put big valves in and port a set of heads, only to have them crack.

gb