Thermostat Housing Won't Stop Leaking

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1969VADart

1969VADart

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I am getting really frustrated, so I figured I would search out the A body wizards to help me solve this problem. I cannot get my thermostat housing to stop leaking. It is weeping quite a bit around the seam where it joins the intake. I have tried two different types of gaskets, two gaskets along with gasket sealer, and then I just went back to one factory gasket. The housing and intake had been powder coated previously, but I stripped both down to bare metal. Changing this is obviously a constant mess-making endeavor. The underside of the housing has grooves that the thermostat seemingly sit in, but those grooves are obviously larger than the thermostat. Unfortunately, I don't have a pic of the underside of the housing to show what I am talking about. But this is what the intake and housing (mounted) looks like. Any advice on how to stop this leak once and for all would be greatly appreciated. Thanks.

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I had a similar problem and here is how I fixed it. You will need access to a lathe for this.
First I faced the gasket surface flat. Then I machined the gasket surface again another .004" but I stopped just after the bolt holes leaving a ring about .125" wide. You can see in the photo. It's the red ring. Now when you tighten down the bolts it pinches the gasket in place.
I realize that not everyone has the ability to do this but it's worth the trouble to find a machine shop that will do it for you.
Ted

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I used the gasket with a rtv sealer and mine still leaked. Cleaned it up again used a new gasket with permatex aviation sealer and no more leak.
Yote
 
DusTed74 said:
I had a similar problem and here is how I fixed it. You will need access to a lathe for this.
First I faced the gasket surface flat. Then I machined the gasket surface again another .004" but I stopped just after the bolt holes leaving a ring about .125" wide. You can see in the photo. It's the red ring. Now when you tighten down the bolts it pinches the gasket in place.
I realize that not everyone has the ability to do this but it's worth the trouble to find a machine shop that will do it for you.
Ted

View attachment 1715031826
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I had trouble w/ two diff housings leaking on my r/. I did the exact same thing as described here to my chromed alum. housing, it works !!
 
Well since I was taking it apart anyway, I figured I would snap a couple of pics of the thermostat housing. Note in the second picture that the recess in the underside of the housing is bigger than the diameter of the thermostat. Any additional thoughts based on these pics?

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That mating surface in the second pis looks pretty waffled to me. Take a piece of wet or dry sand paper, lay it on a flat surface, and sand that thing flat, by gripping the neck and moving it around on the sand paper.

The stat fits like most I have ever seen.
 
Take it to a hardware store and buy an O-ring for the ID of that housing, and use sealant on the bolts as they may not be blind anymore. O-ring will seal with pitting issues of housing.
 
pishta said:
Take it to a hardware store and buy an O-ring for the ID of that housing, and use sealant on the bolts as they may not be blind anymore. O-ring will seal with pitting issues of housing.
Click to expand...

Should an O-ring seat into the groove that the thermostat sits in?
 
1969VADart said:
Should an O-ring seat into the groove that the thermostat sits in?
Click to expand...
best to use a thick old piece of glass, laid on a flat table or something that is flat. sand that puppy till its smooth. I`d take it to a machinist and have him machine the bolt area down, quit just after the bolt holes. creating a raised area for the gasket around the stat. it will fix about any leakage problem with any housing. quite screwing w/ it and do it, u won`t be sorry.
 
That water outlet surface looks like crap. I would replace it. If you get a chrome one, block sand the finish off the gasket surface.
 
that link to ebay. describes a "chrome steel" thermostat housing. Obviously misleading. It's chromed aluminum. Probably Chinese manufacture. Not my cup of tea. Shiny doesn't make it better.
 
1969VADart said:
Should an O-ring seat into the groove that the thermostat sits in?
Click to expand...
the largest OD the stat housing can receive an O-ring in. Id say just outside of the stat itself. Its odd that the stat is smaller than the housing itself, its usually a nice fit. Some stats have a rubber ring around the stat itself, or its part of the gasket set. I wonder if that's a Chevy housing as one of those is the same as Mopar Bolt spacing but uses a different stat? (Not likely as it has a receiver for the stat as GM has receiver in intake side) check this out...

"..One is the older large size with a center to center bolt pattern of 3.25 inches. This pattern was used on all v8 engines from 1951 to 1978 ... The thermostat diameter is 2.49 inches for this size housing. The other water outlet bolt pattern is 2.875 inches. This pattern was used on all slant 6 engines and the newer small block engines made after 1978. The thermostat diameter is 2.125 inches for this size housing....In addition some of the thermostats were constructed to work in conjunction with the water outlets bypass and use a different size Thermostat. Most of these thermostats are 2.55 inches..."

So maybe the stat housing you have is a generic cross-platform design that sort of fits many apps.
 
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rustycowll69 said:
that link to ebay. describes a "chrome steel" thermostat housing. Obviously misleading. It's chromed aluminum. Probably Chinese manufacture. Not my cup of tea. Shiny doesn't make it better.
Click to expand...
I own two of these and can tell you there is nothing wrong with it and will seal. I cannot attest to your statement but feels heavy not like aluminium.
 
I had the same problem, I got the billet aluminum form Mancini and a FelPro gasket.
It so far is leak free.
 
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