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Bugger! Sheared Bolt..

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Right, 10min Job....yeah right! Started to strip Duff Alternator and couldnt get the bottom 8mm hex out! Plus gased for awile and tried again....SNAP!....Bugger!

Welded a nut to the stud that was left, but no chance. Just sheared again, soooo only option i can see is to drill out.

At present it is a threaded 8mm blind hole with sheared bolt in it. What i am thinking of doing is drilling right through as a clearance hole. Is this a wise idea in this area of the casing? I cant see an issue with it, but.....?

Any ideas, comments


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That bolt is into alloy isn't it? You can take the whole alloy casting off and do the job on the bench. I recently replaced the 'P' gasket on a 300TDi, and that casting had to come off. It would have to be a very accurate drill to remove the bolt only - it might be ok to drill right through with an M8 drill and then use a nut/bolt. It looks like it might even be possible to attach the alternator to the casting and then fit it as an assembly if that would make it easier.

Mind you, some of the bolts that need to be removed to get the casting off are a bit prone to shearing.


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Would have thought it would be a right bu&&er to drill out in situ accurately. Suggest removing casting as Les says and do it on the bench. You should be able to get at all the bolts if the alternator is still attached. Then you can do the P gasket as well! :P

I can confirm that the bottom mounting hole for the alternator is a clearance one, the thread is tapped into the casting, though IIRC there may be a thread insert in the alloy. Casting costs about £60 IIRC from when I needed one a few years back.

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In the end, removed Rad (needed cleaning after Billing) Ground the sheared M8 bolt flush with the mount and drilled out to M10. Needed to open up the lug on the alternator to clearance.

Cheers for all the advice, had consider replacing P gasket! But from previous experiance, the casting and bloody pulley bolts like to shear aswell!!!

If it aint broke....leave it alone...

Cheers for the advice

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