Heater core connection

91 OCC Replacing leaky heater core, Have one "quick connect" and other side already was 5/8 hose and gates clamp. Replacement is aluminum construction. Should I smear silicon on "quick connect" to assure sealing? Anything to put on gates clamp side for sealing so I don't tighten clamp so hard I bend or break the aluminum?

Nothing needs to go on the clamp side because that is what the clamp is for. Slide the hose over the connection and snug up the clamp. Don’t go caveman on it and nothing will get crushed. Not familiar with any quick connects on these cars but I would assume that nothing is needed there either. If it doesn’t seal I would eliminate it and use a clamp.

The quick disconnect has an O-ring in it, so it should seal without an issue. You can replace the hose with the quick disconnect, and put a regular hose clamp on it. If you delete the valve, you need to put the restrictor valve from a 92 or later, and block the vacuum line. You must also put a direct hose to the radiator.

I must have got lucky. The O ring in that 31 year old quick connect didn't get lost or break. I didn't even know about it but figured something had to make the seal. Thanks for all the advice. Next 2,000 mile trip north will have some comfort.

Just a note to anyone undertaking 91-93 heater core replacement. If you're replacing "quick connectors" , both heater core connections are 5/8. The heater bypass valve (under the hood) has one 5/8 and one 3/4 pipe. I used 5/8 hose connections on both with success. Do not use a 3/4 hose or it will leak at the heater core under pressure.

Walterf wrote:

Just a note to anyone undertaking 91-93 heater core replacement.  If you're replacing "quick connectors" , both heater core connections are 5/8.  The heater bypass valve (under the hood) has one 5/8 and one 3/4 pipe.  I used 5/8 hose connections on both with success.  Do not use a 3/4 hose or it will leak at the heater core under pressure.  

The 91 models have a completely different valve assembly that is vacuum operated via the HVAC control panel. You can replace the vacuum activated unit with a 92-93, but you must plug the vacuum line from the HVAC unit. I believe there is a restirictor valve that will fit from a mid 90s Camaro, and it has 5/8" lines on both ends. I have one in my 92 OCC.