Leaking Thermostat Housing

[SuperHart]

There have been several mentions in the past about leaking occurring when using the small block thermostat housing that uses the rubber O ring seal. Just wondering if any of the members have been able to solve the problem WITHOUT throwing the O-ring sealed housing in the trash. In theory this style of housing should work well especially with ease of removal since there is no stuck gasket to fool around with.

I have closely examined the rubber O ring seals that come with these housings and have noticed a potential defect in some of them where the two O rings are fused together. I wonder if that is the source of the problem and if anyone else has experienced the same thought and devised a correction. Please don't tell me to trash the housing and get one with a gasket. I'm looking for any legitimate fixes, thanks.

[Roscoe]

I use a silicone grease prior to tightening. Be careful and tighten the housing evenly. Any slight 'cocking' of the housing can cause leakage.

[marcalan]

I use RTV on the o-ring where it mates to the surface of the intake manifold. I have this type of housing on two different vehicles now with no leaks. I have removed one of them once to change the thermostat and had no problem with removal or afterwards, just be sure to clean of the gasket material. I do not put a lot on, a thin layer seems to work.

hope this helps

[RedBarchetta]

Originally Posted by marcalan

I use RTV on the o-ring where it mates to the surface of the intake manifold. I do not put a lot on, a thin layer seems to work.

Same here. Hasn't leaked yet.

-Dean

[CBattaglia]

Mine was leaking with the traditional gaskets. I switched to the O-ring and have had no problems since.

[patrickt]

Magic Goo:

[w-lewis]

I used a conventional gasket arrangement with a factory look alike overflow tank and it always leaked. About a year or so ago, I bought a FinishLine Overflow tank that used o rings instead of conventional gasket. It also leaked. In looking closer, I noticed the chrome thermostat housing was slightly warped a bit. You could place it on a flat surface and clearly see where you could slide a piece of paper under the center section, while the ends were firmly touching the table top. I planed down the surface till it was flat, reinstalled it on the engine and it hasn't leaked since........till now. I checked the two housing bolts and they were each about 1/4 to 1/2 turn loose. I tighten the bolts, drove the car once, parked it and it appears to be dry after about a week sitting up. Does anyone know the torque rating for the two thermostat housing bolts?
Walter

[bobcowan]

I use the chrome piece with an O-ring that so many have had problems with. It looks good, so I think I'll keep it.

Remove the o-ring. Get a sheet of 120 grit sandpaper and place on a sheet of glass. Rub the gasket surface on sandpaper. That will produce a flat surface that has enough texture to grab ahold of a gasket. Then I use a standard off the shelf gasket, with a slight smear of silicone.

Like anything, torque the bolts evenly and to the proper torque reading.

[SuperHart]

Walter, the water outlet bolts are 5/16x18 so they can be safely torqued to around 15 lb/ft. If using an aluminum intake manifold I recommend a little anti-seize cpd. on the threads to prevent galling.

Thanks everyone for the comments. I too like the O ring housings. When they work they work well. I especially like not having to scrape off gasket material whenever I want to remove the housing. I think I have just run through a string of bad luck lately with these housings. I checked two of them and both were warped. Looks like I need to do the glass pane and sandpaper routine. In the past I have used self-stick 220 grit on a glass pane with success.