Quote:
Originally Posted by Speedy Squirrel
The 964 used these, according to the PET:
Always possible that someone substituted the older style Dilavar. Easy to check with a magnet.
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The stud in the OP pictures is definitely a coated Dilivar stud. I've seen hundreds.
All 964 engines came with a full array of coated, smooth shank, Dilivar studs.
It wasn't until the factory noted an unusually high failure rate of these Dilivar studs that they went back to steel studs in early 993 engines. This was very short lived. Warranty issues (weeping heads) caused them to reevaluate their choice of steel and reinvented the Dilivar. This time with an all thread monstrosity that offered a slightly more aggressive clamping force and marginally reduced failure rate.