RTV sealant is leaking.

[dalegov]

I have a stupid question, but heres to hoping. I used permacure black for a thermostat housing. Let it sit for 3 hours, turned it on, did not leak. When I was driving home from work it started leaking. I got it home and am letting it sit. Is there a chance the sealent will still cure in light of all of that? It was globbed on.

 

[96EXXLTinCO]

Nah, heat from the motor and coolant accelerated the curing. But why didn't you just use a new seal? They're cheap as hell........

 

[Flash]

If you're going to use RTV, this is how you do it.

If you ever want to remove the part again, smear a light coat of oil on one of the sealing surfaces.
Run a bead of RTV around the sealing surface then wait for it to go off but not fully set.

When the RTV is 'off' place the parts together and install the bolts doing them up finger tight taking care not to squeeze the RTV out.
What you're doing at this point is flattening the RTV out and forming the gasket in place.

When the RTV is fully set torque the bolts.

RTV is great when used correctly, globbing it on isn't good, bits can break off and block holes.

 

[BrooklynBay]

Use a gasket which doesn't require any sealant. Fel-Pro makes one.

 

[96EXXLTinCO]

use a gasket which doesn't require any sealant. Fel-pro makes one.

x2

 

[rb142]

I assume this RTV was "globed on" the outside of the housing in an attempt to stop a leak without taking it apart and fixing it right. No it is not going to get any better -- it will get worse. You need to take it apart and change the seal. You probably need a new housing too (common issue).

 

[Mr. Alligator]

Thermostat Housing

I agree that you need new gasket, and very probably also need new housing. Be careful of being too cheap on the housing assembly with internet parts. I bought new set with gasket, sensors, and upper and lower assemblies for about $25.00, but it only lasted a few months before it leaked also. Good luck.

 

[boominXplorer]

Black RTV is for sealing Oil. Red RTV is for sealing coolant.

 

[matt351]

Use a gasket which doesn't require any sealant. Fel-Pro makes one.

Part number by chance?

 

[koda2000]

Black RTV is for sealing Oil. Red RTV is for sealing coolant.

Actually red is high-temp and blue is for coolant, but I pretty much use the red for everything except coolant. For coolant I smear a thin coat of clear silicon on the housing side of the gasket only and I like to dress metal housings with a file. The plastic housing should just be replaced.

For my money Felpro Perma-Seal gaskets are the bomb. No goop required.

 

[SoNic67]

Black RTV is for sealing Oil. Red RTV is for sealing coolant.

+1. http://www.permatex.com/products-2/...l-resistance-rtv-silicone-gasket-maker-detail

 

[alohamonte]

I've been using black on all my tstat housings. Over 225k on my Xplorer never had a housing leak.

I use the rubber gasket that comes with the new tstat and apply the black on the mating surfaces.

 

[masospaghetti]

It's not clear from the OP if he used the RTV in lieu of a gasket, or to just patch a leak.

After a few heat cycles a newly installed part can loosen up quite a bit. The RTV probably cured fine. Check the bolts to see if they are loose.