Will a non operable heater core damage the engine?

I’m needing to replace the heater core on my Cadillac and since the car is driven only on the weekends I probably won’t get around to it anytime soon. If I drive with the heater off will any engine damage occur? How about a temporary fix with a sealant?

- No damage but you will have to stop the flow of anti-freeze from the hoses. Find one of the heater hoses where it comes out of the engine block and disconnect it, with that hose disconnect it from the pipe of the heater core. Lope the other hose from the heater core to where the anti-freeze goes back into the engine . If the hose kinks that’s fine. The fluid is not under that much pressure to force a rupture in the heater hose.If in no way its possible to bend that hose to fit (two different sizes) then you must cap of but ends of the heater hoses out of the engine. I think GM has two different size hoses for the heater core.
- Assuming there isn’t like rust flaking off the inside of the thing and going into the engine, no, it won’t.
If you really want to be sure, disconnect the thing from the engine, and just run a hose from the outlet to the inlet on the engine.
Also, if by sealant you mean stop-leak, that isn’t likely to work for very long. It probably isn’t an actual SEAL that’s leaking, and that’s the only situation in which that sort of thing is a good idea (also it can gum up the whole cooling system, doing FAR more damage than it prevents)
If you mean taking the thing out and using silicone sealant or epoxy or something, that is a better idea, however, it’s usually so much trouble to get a heater core out that you might as well just replace it.