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m54 530 eng head bolt torque
#1
I asm currently replacing a cylinder head on a 2003 BMW 530. Head has been machined( overheated badly) . I installed head bolts # es 72943. On my final 90 degree torque each bolt had a snap during the torquring and now seem very loose. I have experienced this before , but not on every single bolt. The threads were checked as per the BMW tsb before any repairs were attempted, all threads held properly at that time . Is that condition normal, or did any machining it took to correct warpage make the bolts too long.
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#2
Hi James,

BMW has a service bulletin in regards to head bolts and engines that have overheated.

Before you started the repair, you would have needed to try to loosen and torque each head bolt before removal to see if the threads in the block will hold torque or not. If any of the bolts strip out (which is what sounds like happened to you), the OE procedure is to replace the short block. If the heads bolts are able to be retorqued, continue on with the repair.

That being said, you have a couple of choices here. Replace the short block, used or a remanufactured.

The option that may sound better is this - there is a company called Time-Sert that makes a tool set to replace the stripped out threads. It comes with a drilling jig, drill bit, tools and inserts to go into the block. THese are much stronger than Heli-coils. The kit will be fairly expensive, but much less than a new block. You will need to decide if the engine was so badly overheated that it warrants a replacement short block or a repair.
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