Plastic Radiator Tank repair

Sun Jun 19, 2005 11:34 pm

This is a little off topic for even this forum. But you seem like the right people to ask.

I have a late model car with plastic tanks on each end of the radiator. There is a small crack right up on top of one of the tanks. It is about 5/16 inch long. When the radiator is cool, it can not be seen. If you let the engine warm up, a very small bead of coolant will gradually appear (and you still can't see the crack).

Looking on the web, I see repair kits for patching plastic coolant, windshield washer etc. tanks. Not clear from the description if they are supposed to work on pressurized tanks or only on overflow tanks.

Anyone had experience patching a plastic radiator? I was thinking about making a slight groove with a file then filling it with JB Weld. That sound like a good idea or not?

Mon Jun 20, 2005 6:29 am


There is a product called Wet Bond it is an epoxy product.You can get it at a plumbing supply dealer. I have used it on other things but not a rad. Plumbers use it to seal things with as it can be used under water. Hope this helps. 8) :) Bruce

Mon Jun 20, 2005 9:41 am


What does it look like
If it is glass filled nylon material which is most times what they use for the heat resistance you will have trouble getting things to stick. not to mention the pressures What is the pressure on these. I would like to se it. can send a private message if needed

Mon Jun 20, 2005 8:59 pm

Here is what it looks like, probably the material you are thinking of. I couldn't find a pressure label, suppose it is around 15#.

I also thought about just dumping some stop-leak in.


Mon Jun 20, 2005 9:31 pm

You might check with a radiator repair shop. They should know if there is anything that will stick, or may be able to plastic weld it. I have seen plastic gas tanks welded. Kinda reminds me of someone using an over grown hot glue gun.

Mon Jun 20, 2005 9:51 pm
Your local radiator shop can change the end tank. You can get the tank and rubber gasket and change it but the hand tools to open and close the tabs are very handy.

Tue Jun 21, 2005 6:29 am

I don't know if it's the same kind of material but my Dad had his travel tralier holding tank repaired by the RV place near home. They did what they called "welding plastic" they took the parts (he hit something on the road while traveling and busted a hole in the tank) and used a thing like a soldering iron to "weld" or melt the material back together. That was about 5 years ago and it was working fine when he sold it last year. Hope this helps you out.

Tue Jun 21, 2005 7:53 am

The RV holding tank is not the same. The RV tank is the same stuff as the spray tanks you see on tractors with sprayers mounted. You can buy a repair for then at most tractor dealers who sell the tanks. Changing the end tank is the way to fix it.

Tue Jun 21, 2005 9:36 am

Jim, I have a plastic welding kit for my Lincoln. LOL. Seriously I do have one of the plastic welding kits (Jarbor Freight), that comes with several differnet types of plastic filler rods that I have used on severla different items. doesn't look to good, but has always held. Never tried it on anything that flexed the way a radiator does when it gets hot and expands though. If you would like to give it a try i will ship it to you.

Tue Jun 21, 2005 4:38 pm


Depending on you're travels with this car, glass filled nylon is tricky as the glass leaves minnie holes, I asked around and my take would be see if the rad repair would change out, but the crimps are not easy. A new or reproduction one would be my take on this fix. Our shop deals alot with Glass filled nylon and we had a tough time welding plain nylon and hold no leaks at 5-7 psi. this was not glass filled . The welding gun may be more expensive to get and still not fix it.
Hope this helps decide.

Tue Jun 21, 2005 5:13 pm

Go to Wet Bonds .com. The list of material it will bond to will amaze you.But it not cheap,I paid $18.0Cdn. But it worked on everything I put it on.You can even turn bolts and nut on it after it cures. 8) :) Bruce

Tue Jun 21, 2005 6:56 pm

I couldn't find the Wet Bonds web site.

Given the ease of access to the crack on the car and the work involved in removing the entire radiator, I think I will check with a radiator shop and see if they claim any fix for it. Little to loose by trying.

I'll follow up on an off day, which probably won't be until late next week.

Tue Jun 21, 2005 7:31 pm

If you cannot find it under Wet bond try I found it under both. 8) :) Bruce

Tue Jun 21, 2005 10:08 pm

That link took me to an "under construction" web page. I googled it and came up with several sites that I didn't want to click on. Did finally find a Brit site with Mr. Sticky's underwater glue. They had specs. Looked pretty good until I found the max temperature, 200F. That isn't high enough. I suppose to depends on how conservative their ratings are.

Tue Jun 21, 2005 10:28 pm

If you not going to put a tank on it put some K&W Block Seal in it. It will stop your leak and plug up all the partly plugged flues in the radiator. In my 44 years of pulling wrenches I have found out that the best I can do is sorry enough.