Thermostat Housing Leak

[Supra88]

Since I've changed my thermostat/ gasket I've had a problem with a leak. I originally cranked to the factory torque spec plus a bit more and noticed the leak. I pulled it apart and set it to exactly the factory spec, voila the problem went away. It's been about a month without a leak and now all of a sudden I have a leak again. Naturally I torqued it down some more and the problem has gotten worse - WTF?

Did I get a bad thermostat or gasket?

 

[TheFuzz]

Did I get a bad thermostat or gasket?

Probably. I'd start at the inexpensive end and buy a replacement gasket first, see if that solves the problem. I doubt that the problem is directly attributed to the thermostat itself, but stranger things have happened.

 

[Glacierskier]

X2 try a new gasket.... my old fj62 did the same... It was the gasket

 

[OregonLC]

Did it may be get pinched by over torque on the first pass?

 

[Supra88]

I did pull the assembly apart looking for burrs, cuts, etc. but didn't see anything out of the ordinary. The new thermostat looked like it was from a different manufacturer ( still OEM ) than the original one. I'm guessing there's some sort of stack up problem. I may grab my micrometers and measure to see if there's a difference. I've never seen this issue before on a Toyota.

 

[Serge]

I am having the same problem. Did getting a new gasket fix it?

Thanks

 

[APKhaos]

When you drop the new gasket in, clean the joint surfaces carefully and butter it with Permatex Hylomar. Its a great sealant and never dries in the joint which makes dissasembly a snap even years later.

 

[Serge]

Thanks, APKhaos, sounds like a great tip. I have never used this sealant and just read up on it. Seems like a very good product and would be perfect for this application.

 

[rusty_tlc]

There is also an O ring that seals the housing to the block, that should be replaced when you replace the gasket.

 

[Serge]

Thanks, got a new thermostat, gasket and two o-rings ordered from Dan today (along with four brake rotors and accompanying pads) Hopefully this will stop the leak.

 

[Supra88]

When you drop the new gasket in, clean the joint surfaces carefully and butter it with Permatex Hylomar. Its a great sealant and never dries in the joint which makes dissasembly a snap even years later.

x2 - this fixed my leak.

 

[hankinid]

When you drop the new gasket in, clean the joint surfaces carefully and butter it with Permatex Hylomar. Its a great sealant and never dries in the joint which makes dissasembly a snap even years later.

Great stuff.

I've used it to seal case halves on large British bikes; never had a leak between cases or covers.

Nice to keep on hand just on general principle. OT but Permatex' grey RTV sealant is sweet. Seals anything that's relatively clean and dries quicker and a little tougher than regular silicone

Steve

 

[APKhaos]

Hylomar is formulated for typical situations where paper/fiber gaskets are used. I use it on my race engines, which get hours of very high temp running. Not sure I'd want to use an RTV in these. RTV has its place though, and there are some pretty decent materials, expecially for case sealing applications.