Thermostat gasket question

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Thomas Dennis

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I have my 84 Plymouth Gran Fury with a 318. The thermostat housing is leaking. The book I have says install the thermostat then put the gasket over top the thermostat then install the housing. Is that right? It seams that if I did it that way it would leak since the gasket won't lay flat. It's been a while since I changed a thermostat
 
I have tried a few different methods of installing a thermostat, and stopping leaks, one I found to finally stop the leak was using studs into the intake, and lock washers, and a good bead of high temp silicone.
 
I have my 84 Plymouth Gran Fury with a 318. The thermostat housing is leaking. The book I have says install the thermostat then put the gasket over top the thermostat then install the housing. Is that right? It seams that if I did it that way it would leak since the gasket won't lay flat. It's been a while since I changed a thermostat
It might depend if the water pump housing or the thermostat housing are machined for the thermostat. If the water pump housing is machined, the thermostat goes in then the gasket then tstat housing. Just the opposite if the t stat housing is machined. It looks like your T stat housing is steel and not cast and that the thermostat goes in the housing and the gasket on top. I use gasket sealer to keep the gasket in place before bolting it down. Check it out before bolting it down. Figure out how it's supposed to work and pay attention how it comes apart.
 
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A tube of hi temp silicone $5.00 . Surfaces super clean, a medium bead of scone, studs and flat washers, maybe nyloc nuts, tighten a little. 10 minutes and more tighten. Then more. My studs are 7/16" . Allow to dry as long as possible.
 
This is a project car I'm selling. So I didn't feel right about it leaking I'm going to order that other gasket to use when I put the intake on the Duster Thanks everyone
 
If it's a chrome one it is probably distorted. Check it on a flat surface to make sure housing isn't warped. I had to buy a billet one to eliminate mine from leaking. Throw out the cheap chrome one.
 
If it's a chrome one it is probably distorted. Check it on a flat surface to make sure housing isn't warped. I had to buy a billet one to eliminate mine from leaking. Throw out the cheap chrome one.

Or put it in a lathe and turn the gasket surface down .040-.060 , to just inside the bolt holes , leaving a raised ridge to seal the gasket.
Make sure to straight edge the pump flange to see if its warped .
 
This is real simple to determine. The thermostat installs on the side that has the recess for it to fit into. Most times it's on the intake manifold. I've seldom seen the recess on the thermostat housing.
 
Issue fixed When I replaced the original that was rusty crumbs. I replaced it with an oem style new one. What I didn't notice was that the new one had bumps near each bolt hole. I filed those flat and installed it. Doesn't leak anymore Only removed it twice before I noticed them
 
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