273 thermostat housing leak- mystery solved!

[yarcraft91]

I've never been able to get this housing to seal completely and I've been trying for 37 years. It always seeped a little coolant and it was getting worse. Thanks to this forum, now, I know why.

I found several related threads here and learned several of you reported your housings were warped. So, I decided to used 600-grit sandpaper on a flat surface to make see if my housing sealing surface was flat. Sure enough, it was a bit warped, so I sanded, and sanded, and sanded as the sealing surface trued up and shined up. Once it was nice and shiny, I saw the problem. The housing has a fine crack between one of the bolt holes and the housing dome, running right through the sealing surface. No wonder it always leaked.

So, $5.49 gets me a new housing through Advance Auto. I'll put a new Stant SuperStat in the housing and should be good to go.

On to the next challenge.

 

[clhyer]

:thumrigh:

 

[RedFish]

A new one may not be exactly flat. Most times it's the chrome ones that leak.

Dont forget to put osme sealant on the bolt threads. I replace those 2 with stainless bolts whenever opertunity knocks.
Happy moparing

 

[yarcraft91]

Well, got the new t'stat housing, it was not chromed and the mating surfce was flat. Installed with a good FelPro gasket and sealant and, voila! After 30+ years of grief, no coolant seepage! Wish I'd found that hairline crack back when...

 

[cudaspaz]

I used a billet housing from Mancinis, still leaked.

Had to get a new, flat wet stone and meticulously cleaned up the stat housing mating surface on my intake which had some decent pitting.
That finally cured my problem.

 

[cudajim]

I had a similar problem with an oil leak on my 273. The oil filter adapter always leaked no matter what I did to it. Before I owned it the dealer had "fixed" it using RTV and it probably worked for about 10 minutes. Anyhow I cleaned it really good one day and found a crack. I replaced it and it never leaked again.

 

[b-sting]

I've never been able to get this housing to seal completely and I've been trying for 37 years. It always seeped a little coolant and it was getting worse. Thanks to this forum, now, I know why.

I found several related threads here and learned several of you reported your housings were warped. So, I decided to used 600-grit sandpaper on a flat surface to make see if my housing sealing surface was flat. Sure enough, it was a bit warped, so I sanded, and sanded, and sanded as the sealing surface trued up and shined up. Once it was nice and shiny, I saw the problem. The housing has a fine crack between one of the bolt holes and the housing dome, running right through the sealing surface. No wonder it always leaked.

So, $5.49 gets me a new housing through Advance Auto. I'll put a new Stant SuperStat in the housing and should be good to go.

On to the next challenge.

Hey man i have seen the fix for all leaky thermostats in all mopar big and small blocks .
Go to Terrysautolab.com and check it out i have 2 of these on a small block and a big block and they work.