I have a 94 4-Runner. On the front of the engine there is (a goofy) clamshell type coupler that the radiator hose connects to. It's leaking enough coolant to be an issue. I've tried replacing the the "O ring" which is actually square. Sealing it with gasket sealant. Tried putting a gasket in between the two metal pieces. I'm going to pull my hair out. Stupid design, I see no reason why they just didn't bring a hose out of the front of the engine, off the water pump going directly to the radiator. But it there and it leaks. Any ideas. I'm at a loss. Thanks

 

I have no idea what your talking about?/

Do you mean the Thermostat Housing on a 3.0

The only think I can think of.

Other then that I have no ideas Something added aftermarket .

Picture worth a 1000 words

 

^^ This.

 

OP, what engine?

If it's the 3.0 upper water outlet that attaches to the upper idler pulley, it uses FIPG/RTV in the groove on the upper water outlet and no "o-ring". You must have those surfaces very clean (coolant/oil free) for the FIPR/RTV to adhere properly.

 

http://personal.utulsa.edu/~nathan-b...67timingbe.pdf
(Step 16 of installation.)

As rworegon says, there is no oring (so what you got to put in there is unknown to me). I use a Permatex RTV that claims to be better than others when in contact with water. http://www.permatex.com/products-2/p...-gasket-detail I absolutely agree that the secret to using RTV is to make sure the sealing surface is sparkling clean and dry.

PS If you ever remove the timing cover (to replace the timing belt, for instance) you'll immediately see why the connection is designed that way. But that isn't your problem anyway; all connections have to be sealed, and yours just hasn't been done correctly yet.