water neck (thermostat) gasket

[Edward S.]

Before posting this thread, I check the archives and got a lot of great information about the gasket for the thermostat. While the Fel-Pro 2022 seems like the easiest remedy, I would like to try it with the correct gasket first. I have checked the neck and manifold and made sure they are nice and straight. In reading the archived posts on this issue, I did not see anyone suggest putting a thin bead of the Permatex "Right Stuff" to make up for any imperfection or very minor gap. I did see folks writing about using Permatex Ultra Copper. Is either ok to use? In the past, I simply used a gasket dressing. But, on my '66 I seem to remember changing the thermostat several years ago and getting a perfect seal was a PIA.

Any insight would be appreciated.

[Michael M.]

Re: water neck (thermostat) gasket

Edward, if both surfaces are nice and straight I would not use any type of Permatex. When ever I did use something other then a gasket it seemed like after heating up the engine a few times I got leakage that ran down onto the intake manifold. I am sure you will get plenty of opinions on if you should use something other than a gasket.

[Joe L.]

Re: water neck (thermostat) gasket

Before posting this thread, I check the archives and got a lot of great information about the gasket for the thermostat. While the Fel-Pro 2022 seems like the easiest remedy, I would like to try it with the correct gasket first. I have checked the neck and manifold and made sure they are nice and straight. In reading the archived posts on this issue, I did not see anyone suggest putting a thin bead of the Permatex "Right Stuff" to make up for any imperfection or very minor gap. I did see folks writing about using Permatex Ultra Copper. Is either ok to use? In the past, I simply used a gasket dressing. But, on my '66 I seem to remember changing the thermostat several years ago and getting a perfect seal was a PIA.

Any insight would be appreciated.

Edward------

Use gasket GM #10105135. This is a conventional style gasket but it has a silicone rubber sealing ring on each side. It requires no added sealer and no one will ever know it has a silicone sealing ring.

[John F.]

Re: water neck (thermostat) gasket

I have never had a leak using the gasket only from your local auto parts store. Just clean up both surfaces. I use a wire wheel on a drill.

[John D.]

Re: water neck (thermostat) gasket

When restoring the 57 to 65 FI's I always resurface the water outlets on a surface plate with various grades of sandpaper. Never saw even one outlet that didn't need it. Try sanding a cast iron 63 to 65 water outlet. Not fun but the end result is perfection.
A typicaly gasket from Car Quest does the job. They have one that is shaped quite close to the outlets also. C25930 by Victoro Reinz. I used 100's of them with not one leak providing I lap the water outlets flat.
Remember I said "Surface Plate". Not some hunk of glass or big buck kitchen counter top scraps. JD

[Joe L.]

Re: water neck (thermostat) gasket

I have never had a leak using the gasket only from your local auto parts store. Just clean up both surfaces. I use a wire wheel on a drill.

John------


You've been fortunate as the thermostat housing gasket often leaks. And, GM didn't come up with the silicone-beaded gasket because the old style worked just as well. Using the silicone-beaded gasket I described above will eliminate leaks even if there is a minor surface imperfection.