Thermostat housing to head still leaks?

[lil corb]

So I have replaced my crappy T stat housing paper gasket with an oem one:EXTREME PSI : Your #1 Source for In Stock Performance Parts

I scrapped the old gasket off the head and t-stat housing and I am still leaking from under the housing. I was thinking it was going through the bottom bolt hole so I RTV Ultra Grey'ed the the threads but STILL LEAKS! I was under the impression that Ultra Grey shouldn't be used when a good gasket is used but I'm running out of ideas and thinking of ultra grey'ing it around the outside of the gasket. It's not a massive leak but small drops.

When I removed the housing, I checked for cracks or warpage on both mating heads and it was fine..

Any ideas?

Thanks

 

[luv2rallye]

I've found Permatex Ultra Blue RTV Silicone Gasket Maker 77B works best on thermostat housings.

 

[WES_393]

I was always taught RTV or gasket, never both. I'd only suggest Ultra Blue RTV for a 2g because they don't use a gasket. But for a 1g I would recommend installing the gasket completely dry.

I'd also check the mating surfaces with a flat edge to make sure they aren't warped.

 

[luv2rallye]

Well I can't argue that for most gaskets and that normally works here too. It's just been my experience that smearing a VERY thin coat on both sides of a thermostat paper gasket has solved many a water leak. Especially if the surfaces aren't absolutely flat or you know there's a leak there. I wouldn't do it on an o-ring or the 2g turbo's thermostat with the rubber gasket on it though. Just a paper gasket thermostat. But to each his own.

 

[miloolim]

Could be a hairline crack or maybe the tsh surface might not be completely flat.

 

[lil corb]

Thanks everyone for their replies. I am going to sand the surface on both sides down lightly and try again. If that doesn't work I'm going RTV time! (Although I don't prefer this method) Thanks again.

 

[92AWDHX40]

I used some grey rtv and a gasket no problems no leaks.

 

[miloolim]

I would put the housing on a belt sander. You will see right away if one side is uneven.

 

[miguelmcv]

I always use the gasket it self with out RTV, but if I have a leak which is very rare, then I go with Gray RTV and add just a light layer on both sides, practically, you just cover the gasket with rtv and remove it all what you can with your fingers to leave just a very tiny rtv on both sides and that will fo the trick and your RTV will not come out when you tight the bolts and looks like a mess.

 

[lil corb]

I always use the gasket it self with out RTV, but if I have a leak which is very rare, then I go with Gray RTV and add just a light layer on both sides, practically, you just cover the gasket with rtv and remove it all what you can with your fingers to leave just a very tiny rtv on both sides and that will fo the trick and your RTV will not come out when you tight the bolts and looks like a mess.

So sand it down to make sure it's flat, Then light coat of RTV on both sides of gasket then bolt it down!

Got it, thanks!

 

[lil corb]

So I actually removed all my hoses and looked at the housing up close. Still had very minor parts of the old gasket. Razor bladed it out and no more leaks!