Leaking thermostat housing

95Cobra302

Founding Member
Apr 9, 2002
394
3
19
Daytona Beach, FL
I picked up a chrome FMS thermostat housing awhile ago and threw it on, even though I heard of all the troubles some people on here have had with them. It just started leaking and I'm wondering if anyone has found a fix to it or should I just paint the original one and put it back on???
 
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One thing I always have trouble with when putting a thermostat housing on is trying to keep the thermostat seated in the housing and not letting it slip between the intake and the housing.

A few tricks I've learned:

1. Only use a thin film of RTV on both sides of the thermostat gasket.
2. Get the sealing surfaces surgically clean with a razor and some brake cleaner on a rag.
3. Use a dab of some black or hi-tack RTV to keep the thermostat seated in its groove while installing.
4. Get a thermostat gasket with an adhesive side (made just for this reason).
5. Put thread sealant on the housing bolts that go into the water.

Good luck!
Wes
 
Over the years I've tried two different FRPP chrome t-stat housings. I was never able to get the big bolt head thingy on either one to seal completely. I tried teflon tape, plumber's putty and even putting an o-ring under it. It always seeped, no matter what. I finally took off the second one and polished up my old one. Good nuff.
 
One thing I always have trouble with when putting a thermostat housing on is trying to keep the thermostat seated in the housing and not letting it slip between the intake and the housing.

A few tricks I've learned:

1. Only use a thin film of RTV on both sides of the thermostat gasket.
2. Get the sealing surfaces surgically clean with a razor and some brake cleaner on a rag.
3. Use a dab of some black or hi-tack RTV to keep the thermostat seated in its groove while installing.
4. Get a thermostat gasket with an adhesive side (made just for this reason).
5. Put thread sealant on the housing bolts that go into the water.

Good luck!
Wes

That is how I do it and have never had one leak ever, there is some good advice offered in that post, that or ditch the FMS cover. As soon as I read your thread title I knew it was the infamous leaky chrome cover lol.
 
Have you checked the housing's edge for plumb?


Wes's post was excellent. Another way of keeping the stat from dropping out involves looping a string through it and back out the housing's hose bung. Just keep the string taut.
 
I went threw two of them myself and was unable to stop the leaks. You would think FMS would redesign the thing :shrug: I ended up getting one from autozone with the removable plug for the autometer gage temp sensor. I cleaned up all the casting flash and powder coated it myself with reflective chrome. Looks good, no leaks. :nice:
 
I ended up getting one from autozone with the removable plug for the autometer gage temp sensor.

I would not use this port for your accurate temp gauge. If the stat sticks closed, the gauge will not relate accurate engine temps to you.
I put the stock sender in the stat housing and the aftermarket gauge sender in the stock sender location on the intake manifold.