Rocker bolt stripped thread

[DJM]

Great forum, and I've been using the advice on it for a while. I've now done something stupid and can't find a good solution.
I am installing 964 cams into my 3.0SC, and am just about to setup the timing. I was torquing up the #1 intake rocker bolt and it just didn't reach the 18Nm. I then noticed that the bolt was turning in the nut but not moving in or out as it turns. I think I've stripped the thread in the nut or off the bolt, but the bolt now won't come out. Any ideas / recommendations?

[TimT]

Need more info

are you talking about the bolt to adjust the valve lash? or the bolt to hold the rocker shaft ?

[DJM]

The bolt to hold the rocker shaft. I can't tighten it up and I can't get it out.

[K Sykes]

Are you talking about the Allen nuts that expand the shaft? If so are you turning the smaller one or the larger one? And are you counter holding the one you are not turning?

[chris_seven]

Nightmare -

If you can put a key into the bolt and get at the other end and apply a small force to the end of the bolt it may just grip well enough to wind itself out.

Don't push on the nut - just on the bolt.

Good Luck

[Lapkritis]

If what Chris recommends doesn't work then I would try the same method but spin the bolt rapidly with air while applying the same lever pressure to the bolt through the center of the stripped nut. Apply little to no pressure at the air tool end.

[DJM]

Thanks guys. Tried applying pressure and tried speed, no joy. Instead, I unbolted cam chain cover, couldn't remove it due to the cam, but had enough clearance to punch the shaft, bolt, nut, collar assembly out.
Will be purchasing a set of new bolts, nuts and shafts.
Anyone seen this happen before? I was using the directions from Wayne's engine tear down book and was holding the nut while turning the bolt.

[Walt Fricke]

Don't recall having this problem. I think I broke a bolt, and maybe stripped or almost stripped the bolt inhex. And the expanding ends of the shaft. But not the threads on the bolt or nut.

Did this turn out to be, in a sense, a self correcting problem? As the stripped threads stripped themselves a bit more as you tried to get them to grip each other, would that have released the clamping force, which in turn allowed the tapered pieces to back out a hair, which released the expansion against the cam carrier bore? Just like unscrewing things a bit, as in normal work?

Sounds like spinning clock and counter clock should both help with this machining process?

[TimT]

Since you drove out the whole rocker shaft assembly with force, you may have damaged the rocker shaft bore. There is a possibility that you just created an oil leak.

You may need some additional sealing tricks may be needed if the cam tower was not damaged to badly, i.e. 935 shaft seals..However since you say you never were able to tension the rocker shaft bolt, the ends of the shaft may not have expanded.... etc..

Additionally there has been quite a bit of debate regarding how much torque the rocker shaft bolts require...