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I have heard a few different ways to fix a pin hole leak in a radiator. I have heard put a small amount of black pepper in the radiator, or use jb weld to patch the hole, and not to use the stop leak antifreeze.

Any suggestions?

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up vote 5 down vote accepted

If you are willing to drain the coolant, most radiators can be brazed or welded to fix pinholes.

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does this include aluminum radiators? – BrettAdamsGA Jan 24 '12 at 16:27
Aluminum radiators can be welded by someone who knows what's they're doing. – Timo Geusch Jan 25 '12 at 0:28

If I didn't really care if I might hurt the car, I might be willing to try JB Weld...

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Seconded. At worst you'll ruin an already-dead radiator, not any other part of the car. I've had luck with this method in the past, although it was a giant gaping hole and I added some radiator stop-leak too after using the JB weld. – R.. Jan 25 '12 at 5:18

I've fixed radiators in the past, but unless your car is one where the replacement radiator is really expensive, you're probably better off just replacing it. A new radiator will usually give much better cooling performance. Last time I replaced a radiator is was just $70 or so...

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