Stainless or galvanized bolts

[sailr4]

In removing my thermostat housing, as others have, I broke one of the bolts. I was wondering if this bolt should be replaced with stainless or some other material since it is attaching mild steel / iron engine parts.

Rob

[KWKloeber]

Just a standard grade metric bolt is fine. 

The issue with the Tstat cap is to make sure that there is good electrical continuity between the T cap, bolt heads, and engine so that the temp gauge and hi-temp switch (if you have one - didn't state which engine you have) operate correctly.

If you depend on the bolts, use copper content never-seize on the threads and a biting lock washer under the heads to make contact, paint over them to hold off corrosion.  Or you can electrically bond the temp gauge sender to the engine negative ground somewhere (like on the alternator negative post.)

Ken

[sailr4]

Thanks Ken.  I have the 25XP. I have not been able to remove the bolt stub yet.  I will try again when the weather warms just a bit.  Might end up drilling out and thru bolting.

Rob

[KWKloeber]

Ya, I stripped the head of one seized bolt on my M-25 10 years ago, tried to drill and E-Z it out. 
My mind has blocked all the sordid details, but the end result was the drill ran off center and thru the side.  I ended up buying a new Tstat cap (with the port for the hi-temp switch this time.)

k