I have just replaced my heater core on my 1990 toyota with the 3.0 engine. I had problems with the flange oring and C clip that holds one of the pipes together. The heater core i bought was aluminum and my pipe going through the firewall was copper. So soldering was out of the question. I could not get the C clip on to mate the pipes together. Rock auto doesn’t offer any heater core that comes with the C clip and correct oring. I simply cut the flange off of the heater core which still leaves about 2” sticking out to clamp too. I used a piece of 5/8” heater hose about a 3/4” piece clamped the heater core and copper line together which solved my problem. Really easy to do doesnt hurt a thing. The pipe on the heater core is slightly larger in diameter but with a little grease on it, it will slide on and clamp tight. It will fit the copper line snug. Ive read several articles about trying to get the correct orings and all that but I didn’t trust any of that. Its too hard to get to the heater core for a leaking oring. Im sure some will say oh you voided the warranty of the new heater core. I didn’t really care about that i just wanted something i trusted to not leak. That is one of the worst setups that i ever saw that C clip is a joke trying to mate those two pipes up Anyway i hope this helps some that is working on the same thing.

 

Good job finding an alternative and thanks for posting it for others to glean from. 👍

 

I wished I would have got pictures of it but it worked great. Its a whole lot better than the oring and c clip Just dont use cheap clamps and it works great. I searched all over reading what little i could about it but I couldnt for sure find a different oring or new c clip but this worked out great.