Crankshaft pulley - stripped thread?

[Shougle]

I recently did a cam belt change on my K series and when I went to tighten the crankshaft pulley bolt it did not tighten properly. I torqued it in stages as I am always cautious in tightening bolts and started at 80Nm, iit clicked so altered the setting to 100Nm but the bolt continued to move for another 1/4 turn with limited resistance. Took out bolt, which seemed OK, but I couldn't see inside the crank to check the state of the threads. Re torqued to 80 and left it (should be 205Nm i yhink). Is it possible to strip such a large thread in steel or am I missing something. Is it safe to run the car with the pulley torqued up at just 80Nm?

[revilla]

I have a vague memory that Rover originally specified something like 165Nm for this and then increased it to 205Nm as they were coming loose, so I really wouldn't run it at 80Nm.

I'd be surprised if you had managed to strip it.

Is the thread possibly clogged with old thread lock? Just wondering if when it firsts seems to go stiff it's just binding on old thread lock compound and not actually nipped up properly, so you need to go a way further before it really starts to torque properly.

Have you got the crank pulley aligned properly, with the little cutout engaged with the raised tab on the cam belt pulley?

I've always given mine the full 205Nm, never felt like it was giving up and never heard of it happening.

One thing I will add though is ... 205Nm is pretty tight. If you're torque wrench is "normal" length and the engine is in the car, you'll be pulling very hard with your arms close to sharp bits. If anything (such as whatever you are suing to lock the crank) slips, you can hurt yourself. Ask me how I know! Deep cut on my hand and two badly cruised forearms. Went back to it with a leather jacket and gloves on and old towels laid over all the sharp bit and made sure the crank lock was rock solid.

[oilyhands]

It is probable that the pulley was misaligned and the torque just forced it into position. I would remove the pulley and inspect the back of the pulley and the cambelt sprocket to see if there is any evidence of a problem. It is unlikely that you would be able to strip the thread as it would require more torque than your arm could apply unless the thread was already physically damaged, the thread is very long and the material tough. It isnt safe at 80nm.

Oily

[Shougle]

Thanks, I will take the pulley off and have another go. The bolt did feel quite loose in the thread for some way in so I suspect there may be damage to the thread cut in the crank. Thanks for the advice on protective closing! Enough cuts on my hand from some of the sharp bits that seem numerous in a Caterham engine bay.

[revilla]

I usually find I can screw them pretty much right in with my fingers, so I wouldn't worry if it feels quite loose turn.

[Shougle]

Thanks for the advice guys. Took your advice and checked pulley alignment, peered into the crank drilling, looked clean and OK, checked the bolt thread was clean and reassembled it all. The bolt screwed right in with fingers and then torqued up to full loading as I would have expected. Engine fired up and all looks and sounds good.

[revilla]