I have a small crack in the plastic part of a radiator. I first applied JB Waterweld, and that didn't work because it didn't bond to the plastic very well. So, I removed the Waterweld by scraping it off with a screwdriver and applied JB Plasticweld. I am going to let it cure overnight. The package doesn't list operating temperatures though. Think this will work well?

  • It may work, but preparation of the damaged area is going to allow it to work or not. You need to rough the area up (scuff it up with sand paper) as well as cut a groove in the crack (grind a valley at the crack). For it to really work, it would need to have material inside the radiator cavity, through the crack itself, then more on the outside. Still it will be iffy as to whether it will work or not. Oh, you'll also need to stress relieve the end of the cracks as well, most likely by drilling it at the ends of the crack. If you don't, it will continue cracking. – Pᴀᴜʟsᴛᴇʀ2 May 29 '16 at 15:26
  • I wouldn't trust it. The first car that I bought when I was 16 had a crack in the radiator in a very obscure spot that the owner didn't tell me about. He filled the crack with some type of plastic bonding compound. It held for about 2 weeks and then I started loosing coolant very quickly. The first time it happened I was driving on the freeway and the car overheated. I was lucky to notice before it caused irreversible damage. – rviertel May 29 '16 at 15:41
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    That being said, I think the best that you'll find is anecdotal evidence either way. Some people have used it and it works fine for them. – rviertel May 29 '16 at 15:49

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