thermostat housing leak

[gaC5]

I changed the intake on my 78 to an aluminum and put on a chrome thermo housing. It has an o-ring for a gasket and was leaking some so I put on a regular gasket to and this stoped it. After awhile it started leaking some so I replaced the o-ring and gasket and it still leaked. I went back to the stock thermo housing and it leaks too.

 

[waterboy1976]

I have a chrome one with the oring, but I also use a little gasket sealer (small 1/16 bead around the outside of the oring, it sealed fine.

 

[JonM]

http://www.permatex.com/right_stuff/right_stuff1.asp

 

[norvalwilhelm]

For all those aftermarket housing take a piece of glass and a sheet of fine emery paper. Using masking tape tape the emery paper to the glass and then true up the mounting surface of the housing. Draw it across the sheet of emery paper, look at the pattern. You will see the high spots usually under where the bolt holes are will touch and show signs of the emery paper.
Keep drawing the housing across the paper until you get a uniform pattern. This is when the housing is flat, no longer warped. It will not leak after this with just the O ring.

 

[wicky88s1975]

I used permatex in addition to the gasket that came with the housing. no Problems.

 

[Mr. Chuck]

This method is great if the mounting surfaces of the casted housing are out of flat by small amount. If your housing out of flat condition is caused by left over casting flash (remnants of the molding process), a preliminary de-burring / removal of the flash with a file or heavier grade of sand paper may be in order. Then the emery paper to give you a nice smooth shinny surface, small surface pits are common and should not cause any leaks. Housing erosion problem are also found when installing new thermostats on higher milage cars. I have had to replace a few housing where owners don't maintain the correct anti-freeze coolants ratio. Some high milage (good for 100K) coolants will turn acidic and attack gaskets and metal surfaces, causing a number of other blown gaskets, leaking freeze plugs, & other leakage problems.

 

[KANE]

I changed the intake on my 78 to an aluminum and put on a chrome thermo housing. It has an o-ring for a gasket and was leaking some so I put on a regular gasket to and this stoped it. After awhile it started leaking some so I replaced the o-ring and gasket and it still leaked. I went back to the stock thermo housing and it leaks too.

Fel-Pro has a great plastic reinforced gasket. It will work even if the surfaces are warped!!

 

[gaC5]

Thanks for the coments. I'll try them.

 

[JohnZ]

GM also has a new gasket with a silicone bead molded on both sides (P/N 10105135) that is just as effective as the (much more expensive) Fel-Pro, and looks like a stock gasket when installed.