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Repairing a radiator leak. On the cheap

1988 Dakota, 209,000mi.

Today, I found the (relatively new) radiator had come off of its upper mounts and had been abraded by the fan to the point where three consecutive coolant passageways had pinhole leaks.

Rather than buy a new rad, I was considering (1) applying JB-Weld to the leaks, or (2) heating leaks with MAPP gas until melting.

Any advice? Do any of these repairs have tolerable (meaning ~20K mi) longevity?

If you’re unable to repair this one, look for an inexpensive radiator from a salvage yard. I got one last year for $30.

On the cheap? Pour a tablespoon of black pepper into the radiator. Start the engine and let it idle. Let us know if it works!


The better of your two options you came up with would be to JB-Weld the places it is leaking. If the damage does not encompass a large area of the radiator, it will probably be okay. If it does, it could start overheating after the repair is made.

As far as using MAPP gas or propane, this is normally accompanied by a brazing or solder rod and is good for repairing brass tanks or sealing leaks where the brass tank attaches to the core. This, of course, won’t work with plastic tank radiators, but JB-Weld will. Trying to melt the core itself in a controlled manner to seal leaks will not likely do anything good for the radiator.

Well, repair complete! (Also, I did the air+fuel filters while waiting for the epoxy to cure).

With the rad out, cleaned the affected passageways w/ acetone, let dry and applied JB Stick to the passageways. Let set 90 min, filled with coolant, let idle until therm. opened, then 5-mi. checkout run.

No leaks so far…