Water pump bolts stuck D3 4.2

Three bolts came out without issue, the rest seem to have bonded with the block.

I can move them back and forth a wee bit but I fear stripping the aluminum, or worse, snapping them off. I was able to work one out about 1/4 turn but am unable to turn it back in from whence it came; It feels to me like I'm buggering up the soft internal threads.

Application is 2004 A8L 4.2 engine code BFM.

How to proceed from here?

Thanks... Mike

I've been there on older cars' water pumps. Some things really should be put together with anti-seize from the factory.

I think the only real choice at that point is to try applying some heat using a torch.

If you end up stripping the aluminum threads, Helicoil or Timesert...

-Uwe-

OK, thanks Uwe; I'll grit my teeth and hope for the best.

Upon reassembly, what shall I apply to the threads to minimize the chance of this occurring the next time; anti-seize, a mild thread lock or other?

Mike

I like NEVER-SEEZ.

-Uwe-

I just realized that I failed to follow up on this. Applying heat was the bomb. I heated the bolts as much as I could with a small MAPP torch, then after cooling they came out with ease. Again, thanks!