I've had a slow coolant leak from my heater core for years. Do I have to remove the dash to replace the heater core? Any thoughts on the various radiator leak sealers available??

Brian

 

My 92 requires the removal of the entire instrument panel to get to the heater core. That means the entire dash and floor console. I looks like you even need to remove the steering column mounting bolts and lower the column to get the dash out. No small job. I don't think it would be hard, just time consuming. Body components are often interlocked and need to be taken out in a certain order. You will need to move slowly and with patients. A very expensive job to pay a repair shop to do. As well I have found that on older vehicles that have seen a lot of sun the dash components get brittle so you might break some plastic mounts that will need replacement.
You can try a stop leak as you have nothing to loose. I would not do a rad flush as that may remove some deposits that are slowing the leak. What's the future of this vehicle? Is it worth all the labor if you can live with the leak? This is why I take great care of my cooling system, doing regular flushes and coolent changes. Just for laughs go to a dealer and get a quote on replacing the heater core.