Thermostat housing question

[snrusnak]

Hey all I have a question. I replaced the oem thermostat housing with the new updated metal 2 piece housing that I bought at autozone. The original one failed shortly after 100,000 miles. I believe the new one is leaking where the 2 parts of the housing join together. The thermostat gasket is supposed to seal there but I don't believe it is thick enough. The thermostat(with the gasket on it) sits in a recess in one half of the housing then the other half of the housing tightens down over top of it. The problem is once I set the thermostat(with the gasket on it) into the recess, it is sitting flush with the metal, and I don't believe it is sealing. Is there a thicker gasket, or has anyone had this issue? Autozone said they don't carry the gasket.

[Tony_B]

Yup! Had the same thing happen to me. Leaks where it is metal-to-metal. I plan on this weekend to cut a gasket out for it or using some liquid gasket material.

Our housing busted open and my wife drive for a few miles with no coolant, so engine may be shot anyways...

[snrusnak]

I replaced it with ANOTHER aftermarket one and seems to not be leaking. If it happens to leak again I'll be doing the same and making my own gasket somehow. I think the best thing would be to cut a piece of gasket material and use it to shim the tstat(with oem gasket) out a little.

[petrified.rabbit]

might not be seated correctly? but there is a possibility that you need a better thermostat, not sure if the oem changed the thickness of the seal going from metal to plastic, but the aftermarket may have not. This thread is really the first time i have heard of the metal thermostat not sealing.

(and i know its op is old.)


odds for you are once it cools down which i am sure it has already, to start it and see how it runs, it would take 3-4 minutes at least to get hot.. so you can run it for a minute to see if it runs..

[petrified.rabbit]

As soon as i hit submit i remembered something, iirc the oem plastic bolts were longer than the metal housing bolts. so the tighten into the head threads without fully seating the new housing. I can't verify this myself, as i have an ecotec. but if you still have the old housing, you could measure or just compare them..

[snrusnak]

I am the OP.

The housing is fully seated, and the joint between the two halves of the aftermarket metal housing are pushed together snug. I can't tighten the bolts anymore as it is all pushed together tight. The issue is that the recess that has been bored into the tstat housing is deeper than the thickness of the tstat gasket. I've used both the oem tstat and an aftermarket tstat and it leaked both times. The gasket wraps the edge of the tstat, so there's really no way of changing the thickness. The problem is that the aftermarket housing has the recess bored/drilled too deep. I'll see if I can make a sketch to illustrate what I'm saying...

[petrified.rabbit]

ok, i understand what you are saying.

I think a simple solution would be to find an oring/gasket that you could stick in the recess first. It would need to be tight, then put the thermostat in, the issue with this may be the two gaskets not sealing together properly or heat changes.

You could also try grinding (its got to be flat) the face of the housing off until the recess is smaller. but i doubt that will work since its not a prefect slip joint (your just make the housings loose to each other).

I feel like this might be the first aftermarket housings i have heard used as well. I woulc also suggest buying some:

Mr. Gasket 77C - Mr. Gasket Universal Gasket Sheets - Overview - SummitRacing.com

and making you own inner and outer gaskets for the tstat. maybe even taking off the original.

[snrusnak]

Yeah that's exactly what I was thinking, cut another thin gasket material to shim the tstat(and gasket) out. I think if you cut a nice piece to use as a shim it's seal ok.

I know you said you understand now but since I took the time to render this terrific piece of artwork I'm still going to post it



Black is the half of the tstat housing with the recess that the tstat sits in.
Purple is the other half of the tstat housing
Red is the tstat gasket
Green is the tstat itself

I'd put a "shim" piece of gasket between black and red on the left side.

[Tony_B]

I'm afraid that our engine is shot now... My wife drove for a few miles with no coolant because the housing (old) broke apart while she was driving. Now my lifters are ticking...

[petrified.rabbit]

lifter tick is typically more of an oil issue then a coolant issue. Are you sure it is the lifters?

coolant would blow a head gasket, kill the water pump, warp the head, etc.