993 crank cracked from bolt failure

[Mahler9th]

This happened a couple of seasons ago... was recently going through some files and pics and thought it might be good to post for posterity.

The engine is a 3.8 race config with a mild set of cams. Revved to about 6500-7000 typically at the time of failure. Ran a stock 993 pulley, but a smaller earlier-style alternator. Heading into the carousel at Sears Point in a race, the pulley bolt broke. Could not determine a cause. Not sure if this could happen on a street car.

The locating pin hole was damaged as a result of the failure. I was able to easliy remove the end of the bolt. I was advised to use one of the Patrick Motorsports pulleys to replace the slightly damaged factory unit, and have it machined to add a second pin. I also had to carefully drill a hole in the end of the crankshaft for the second pin. This was not so easy as the material is hardened.

Got all of that done and then I noticed the extent of the crack by the original hole. Put everything together and unfortunatley oil leaked out steadily through the crack. It was just enough to be messy-- too messy for comfort. It took some cleverness on my part to come up with a fix without removing and disassembling the engine, but I was motivated.

I was able to get it sorted out with some advice from my engine builder/friend, who is much more clever than I. I used a sleeve and a seal with a larger ID. And I had to have the pully machined for a cleverly-placed o-ring.

My engine builder/friend has seen one other crack like mine, and that was on a 3.8 TT motor he built for another friend.

During the prcoess of figuring out the fix, I showed my pictures (below) to some other expert friends, Mike Stimson and Armando Ayala (Pacific Perfmance and Custom Crackshaft Repair, respectivley), and they agreed the crank would eventually need to be replaced. I appreciated their opinions to add to the mix.

None of us knew how far the crack traveled along the crank, so I took my chances. Well, the fix held up just fine for two seasons.

I had the crank replaced by my engine builder/friend last winter. We went with a new GT3RS crank.

By the way, if you are in or visit the SF Bay Area and are doing some P-car related visits, note that Pacific Perfmance and Custom Crackshaft Repair are now in San Mateo, not Redwood City as mentioned recently in Excellence. The shops are right next to each other.

They have some really cool stuff in both shops if you are into crankshafts and cylinder heads. Those guys both do some amazing stuff. Very cool if you are into that sort of thing. They get projects from all over the country.

See pic of crankshaft crack below.

[Mahler9th]

That's Pacific Performance and Custom Crankshaft repair. I am challenged when it comes to typing and spell checking. But I CAN spell. So sorry for all of the typos.

- MM