thermostat install

[gman]

When installing thermostat, do you use just a gasket, just RTV silicone or both? Thanks!

[wcdrake]

I have always been a little leary of silicone when it comes to sealing water components.. maybe others have not had any problem.. I prefer permatex no. 2 for sealing all water connections and have had a lot better luck. Also, a good friend of mine who is an engine rebuilder taught me something very simple when replacing thermostats. He always drills a tiny hole in the thermostat ring (around 3/32 or 1/8 inch) to allow a small amount of water to pass through even when it is closed. This will prevent a motor from over heating due to vapor lock inside the block when it is refilled with water.

[COBALT]

Fel-Pro reusable thermostat gasket (#35562T). It's by far worth the $15 investment.

Otherwise stick with just a plain gasket and copper RTV. Don't use those "sticky on one side" gaskets, or the gray gasket maker crap. They're not worth a damn. The heat will separate the sticky side from the gasket and you'll end up with a leak. The gray gasket maker melts under heat as well.

Make sure that the surfaces are SPOTLESS (use some brake cleaner and some scotch brite). Also, make sure your housing is flat. It'll warp, and you have to use some fine sand paper to flatten it down. Clean out the bolt holes on the intake with a tap and some cutting oil, and use new grade 5 or stainless bolts. Grade 8 will rip up the threads on the intake if you over-torque.

[gman]

Thanks for the replies. I think I might try one of those Fel Pro gaskets. First I've gotta get the broken bolt out of the 'stat housing. The head of the bolt is gone on one of the mounting bolts. This should be interesting........knowing my luck it won't come out. Incredible that it hasn't started leaking yet. I've been drowning it in PB Blaster for the last week or two.

[72MARIO]

GM sells a really nice no too .

[COBALT]

...another suggestion: ditch the pot-metal housing and get a cast-iron one from NAPA. It works well with the fel-pro reusable gasket.

[Ed ke6bnl]

Originally posted by COBALT
Fel-Pro reusable thermostat gasket (#35562T). It's by far worth the $15 investment.

Otherwise stick with just a plain gasket and copper RTV. Don't use those "sticky on one side" gaskets, or the gray gasket maker crap. They're not worth a damn. The heat will separate the sticky side from the gasket and you'll end up with a leak. The gray gasket maker melts under heat as well.

Make sure that the surfaces are SPOTLESS (use some brake cleaner and some scotch brite). Also, make sure your housing is flat. It'll warp, and you have to use some fine sand paper to flatten it down. Clean out the bolt holes on the intake with a tap and some cutting oil, and use new grade 5 or stainless bolts. Grade 8 will rip up the threads on the intake if you over-torque.

I have had to deal with so many stats with all the kids cars and my own that we built an aluminum gasket templete and was fortunate to get a roll of felpro gasket material cheap and pop out 6 or so at a time. I also came accross a stant radiator and pressure cap tester that allows me to test for any leaks with working pressure. Before this I had a tappered rubber stopper that I used a regulator to adj pr. to 13# and would test with that. I feel a lot better with these proceedure and when replacing a stat in my boys 70 c10 we tested the pressure and found small leaks in other places. Ed ke6bnl

[robby]

I like to put in studs and nuts instead of bolts in the intake

[Sierra]

Use the Fel-Pro reusable gasket. It is money well spent and you don't even need to put any gasket sealant on it. You can reuse it whenever you want, and it never needs any additional sealant.