Pin hole in thermostat housing

[Douglasdzaster]

https://tinboats.net/forum/download/file.php?mode=view&id=107978

Hopefully y’all can see the picture I tried to post. 1992 Yamaha 40 MSHQ. There’s a small hole behind where the thermostat goes. There is a water passage in the back of the housing on the right (can’t see in picture). My question is that pin hole supposed to be there? I had ran a wire brush on a drill in the housing a little cleaning and for all I know I may have put that hole there. Hopefully the attachment downloads so y’all can see it. I appreciate any knowledge you can share on this. Thanks

 

[RaisedByWolves]

That looks a little too neat of a hole to have been made accidentally.

Im thinking it is a drain hole so water wont freeze in there.

 

[DaleH]

Agree ... that or a vent, to prevent air blockage.

 

[nccatfisher]

TurboTodd would know.

 

[Douglasdzaster]

Thanks for the reply’s gentlemen. I am very appreciative as always. One more question should I use a sealant on the new gasket when I install the new thermostat? If so what’s best to use?

 

[CedarRiverScooter]

I don't use sealant, just make sure surfaces are clean & flat. Sealant just makes the next repair harder, IMO. Gaskets are designed to seal by themselves. If the surface is knarly then sealant would be justified. Permatex black stuff is good.

Another tip is to run a tap into the threaded holes to clean out the crud. I also use a little antisieze on the screw threads but that is controversial due to the change in friction coefficient for torquing.

Clean threads will help with the clamping & sealing.

 

[Douglasdzaster]

Thanks for the input. Got a new cover coming with new bolts.Threads are clean. For a final cleaning I was going to wipe it with acetone.Non metallic marine antisieze so there’s no bad reaction. Thought I had it covered but it hadn’t dawned on me the antisieze could effect torque.

 

[Douglasdzaster]

Check this out. Smart bolts. http://www.smartbolts.com/dti/
The color of the head changes from red to black when proper torque is achieved and it does this every time it’s removed and put back. Lubricant has no effect.