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Whilst removing the exhaust housing from my Garrett GT28R turbo, the thread of the bolts sheared off and needs replacing.

example

It's a blackened bolt, so I'm not sure if this has any significance? (heat resistant coating?). My question is can I replace these bolts with standard zinc plated grade 8.8 or grade 10 steel bolts? Or do they need to be some kind of heat resistant bolt/coating?

Thanks!

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    grade 10, and use high temp anti-seize on the threads.
    – Moab
    Commented Aug 8, 2020 at 17:29
  • is there a risk of the anti-seize helping the bolts come loose over time? Commented Aug 8, 2020 at 18:26
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    @SeanChapman anti-seize does not mean “come loose” unless you left it loose in the first place.
    – Solar Mike
    Commented Aug 8, 2020 at 21:25
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    "is there a risk of the anti-seize helping the bolts come loose over time" not if torqued properly.
    – Moab
    Commented Aug 9, 2020 at 16:54

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Any zinc coating is a serious NO ( liquid metal -steel- embrittlement risk of stressed component like a bolt). The exhaust components can get pretty hot . Any standard steel bolting ( eg.chrome moly ) is going to start relaxing at 800 F, I think design temperatures are well above that. [relaxing comes at lower temperature than creeping]. I expect they are nickel alloy , there are a bunch so not worth listing them . And ,you only can get what is available in the automotive world, So you need to check with manufacturers or re-conditioners. Or , I can promise you that MP-35N would be great,Standard Pressed Steel , Jenkinstown PA , or Rolled Alloys . ...Just stick with manufacturer and reconditioners.

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