I am putting new water necks on my flathead and am curious if people prefer using RTV gasket maker or the gasket that comes with the neck (which seems a little thin)

 

I use a thin film of RTV in the recess of the housing to glue the thermostat in, then smear a thin film of RTV on both sides of the gasket. It's very easy for the thermostat to slide partway out of the recess and then you have a guaranteed leak.

 

I'm not a flathead guy, but for everything else...I use the paper gasket with a thin coating of RTV. Not too much...you don't want gobs of that stuff in the inside of your cooling system.

Dan

 

I am so sick of cork or paper gaskets leaking even with a bit of RTV. I always wonder why I pay good money for a gasket only to have to put yet another sealer on it to make it work. I have moved on to The Right Stuff gasket maker. LOVE THE STUFF! It is in a can, easy to apply, little pricy ($14.95 per can at AZ) and you torque it down right away, no lag time. It really glues stuff on. That's what I use.

 

This is going to be a stupid question but is the thermostat supposed to sit neatly in the recess in the water neck? Mine is larger. In my case the gasket and the thermostat overlap.

 

Yes, the thermostat should be completely within the housing's recess, even a little sloppy (I'm talking diameter).

 

I use RTV on the water necks and water pumps. The sealing surfaces are rough from years of rusting so I don't think a gasket by itself would seal.

 

I bought the necks from Speedway (offenhauser) so I am assuming they are more correct. (the old ones are so degraded it is hard to tell what they are.) The neck has a diameter of 2-3/16" while the thermostat(duralast) is 2-1/2" in diameter. This is a thermostat that the local auto place swears is for this truck. I checked the old thermostat and it is 2-1/4" which is also too large. Where does one find a smaller thermostat. They don't list diameter when you buy one.


Frustrated,

 

Try cross-referencing this number: Gates #33008

More Information for GATES 33008

Past thread:

https://www.ford-trucks.com/forums/1...hermostat.html