Good evening - got a little time in on the car today. Question: what are you all doing with a leaking aluminum thermostat housing on a 400? Replace it with a cast one from a newer car, replace it with a new aluminum one, assuming it's warped try to sand/grind the mating surface level again, RTV the crap out of it, or something else? I'm guessing either they warp from being over-torqued or from heat?


Bringing back lots of memories from working on the 70 Monte Carlo I had as a kid - especially repeatedly hitting my head on the underside of this massive hood that doesn't open very much. But, it's all fun!


Don

 

Replace with steel / iron unit is the factory approved repair

Originality sticklers often prefer the AL type.

 

I just replace it with a cast piece from the auto parts store. I learned my lesson on chrome ones back in the 70's also.

 

If you want to keep the original t-stat housing, simply sand the gasket surface using wet-or-dry sandpaper on a flat surface (glass is ideal). Be careful not to rock the housing as you sand, which will make it worse.

 

Once you have the stat housing flat use spray on gasket sealer on the housing to gasket interface. Apply a thin film of RTV to the intake surface. This usually cures the leaks for me. This method also allows for easy clean up/gasket removal on the next service. Also apply RTV to the fastener threads as coolant can wick up that way too. Allow everything to cure before adding coolant.
Another tip is to use the Stant HD tstat. Its got a different part number. It regulates better and is well... HD.

 

That is an excellent point. The t-stat housing bolts are among the few bolts on an Olds motor that thread into the cooling jacket and require sealer.

 

True that
in fact, that is one of the only sites where an Olds engine has a fastener exposed to anything oily or pressurized. Maybe the lower fuel pump bolt also. Lower two 1/4" water pump bolts.

I just acquired a new tube of Yamabond #4 semi hardening sealant. Designed for motorcycle case halves, I have found it handy for many other sealant jobs as well. I reckon there is probably a similar Hondabond...

http://www.ebay.com/itm/NEW-YAMAHA-Y...dR6VKo&vxp=mtr

PS I hate the phrase "one of the only"
It is meaningless. I use it for sport.

 

This is a common problem. I use double gaskets with RTV to help seal. I went through a 10 pack running 2 Olds powered vehicles.

 

One of the only
One of the only
One of the only