Toyota does a good design job of making a 95 Camry heater core easy to get to. But you have to disconnect the core inlet and outlet from the heater tubes thru the firewall first before you can slide out the core. The hassle is with the replacement and reconnecting the tubes and core. At the junction of the tubes and heater core inlet and outlet, they are held together by an O ring and a tiny clip that clips around the tubes lips and the core flange lip. That's supposed to hold the joint together under 13 lbs. of pressure, and one of the joints has a leak when I got the car warm again. Does anyone know...can I use an RTV sealant in addition to the new O rings and new clips? There HAS to be something better to hold the junction together! Any tip on this? Thanks.

 

I have no direct experience with the heater core, but o-rings are designed to seal better under pressure. The pipe that goes into the back of the water pump also uses an o-ring to seal. I suspect there is some scale or other dirt preventing the o-ring from making a clean seal. Are you using new o-rings and have you tried cleaning the surfaces with fine emery paper, maybe 800 -1000 grit? I guess you can try touse RTV, but it should not be necessary.