While changing the oil on our old spare 95 Explorer today, I noticed a steady drip of coolant from the radiator. I had not noticed any pooling until today, but it is dripping enough to mark its territory. I spotted the leak on the radiator tank. There appears to be a small crack on the flat forward area of the plastic tank, right on the opposite side of the upper inlet. Other than this, the radiator still appears very clean inside & out.

Has anyone ever repaired a small plastic tank leak such as this with JB Water Weld? I've read more than a few posts of people sealing plastic tanks with this stuff that last for years. I figure it's worth a shot. If it doesn't work, and I have to replace the radiator, not much time or effort lost.  If it does work, $220 saved for a while.

edit: also seems to be suggested to drill a divot into each end of the crack to stop from progressing any further. I haven't removed the radiator yet to check it out. If it's bad enough I'll just replace it.

In college we tried fiberglass with little to no success and JB weld with a bit better success.

Neither one I would really put much faith in.  How much is an ebay aluminum one?

I havent had any particular luck with epoxy and coolant leaks.   Eventually,  heat cycling causes the epoxy to peel right off.

Best thing is to replace the radiator.

I've tried J_B Weld and epoxy but I've never found any type of adhesive that works on plastic radiator tanks. I know there are products available that are supposed to work but I haven't tried them. I have a friend who claims that he's fixed plastic tanks using a soldering iron to "weld" the crack closed. It might be worth a try. Otherwise you're replacing it anyway.

Have you looked at JB Marine Weld?  Supposed to work well in gas tanks and the like.

Without question, on all points.
Adhesives (epoxies) simply don't work well with thermal expansion/contraction

If you're hell-bent on delaying the R&R, I highly recommend Marine Tex. Only because of the ridiculous expense or the unavailability of a replacement, I've successfully used it to patch holes in construction equipment oil pans and front engine covers. Roughen the patch area with medium grit sand paper, ether it clean, and apply the directed thickness. Avoid multiple thin layers. Good luck with it.

I ended up slabbing on some JB Weld plastic epoxy just to get it moving down the road for a few days.
Amazon had blowout deals on radiators, nearly half the price of any of the local shops, so I ordered an OEM style radiator from them /w free shipping via Prime.

I did not like the idea of leaving the epoxy on there long term, especially since I use this truck to go up into the hills for hiking, hunting, camping, etc.

In fact the appearance of the crack looks like it may have developed due to the amount of trails the truck sees, as it appears to be a stress crack from the body flexing at the upper mount location. I may see if I can use a softer bushing with the replacement radiator mount.

I did attempt this but the tank appears to be nylon or some sort of polyamide, so taking a soldering iron to it simply burned it rather than fusing. Nevertheless I ran the iron along the crack to give the epoxy something to grab onto.

I used JB Quick on a cracked seam of a plastic gas tank while it was leaking.  I just roughed up the spot and applied it.  It lasted about 12 years and was still holding fine when I finally replaced the tanks.

I don't fuck around with radiators.  If they are old enough to leak, replace them, unless you like walking on extremely hot summer days.

Believe it or not I have had a much worse repair that held on with JB Weld. Years back I was four wheeling and had another guy on the trail hook up a tow strap to my radiator support (completely ignoring my frame mounted hooks), ripping the tank open near the fill cap. I was able to limp back to the staging area and plastered the entire fill neck with JB Weld, then proceeded to wait there for nearly 10 hours for it to cure. I was able to drive back nearly 50 miles to the nearest town with an auto store that night, and buy a new radiator. By the time I arrived there, the JB Weld had held on, but had gradually swelled to the point that it was a large semi-solid bubble full of coolant.

Worked on a Mustang I had years ago for about 2 years. The next time I tried it was a no-go. I never figured out what changed but it saved me money for a while.

Everyone knows pepper works All joking aside, i swapped out the fuel pump on my wifes 02 pontiac sunfire one day and when i was putting the gas tank back i broke the nozzle where the fuel line attaches to the pump, DOH!  got a q tip and some jbweld, put the nozzle back on with qtip inside to keep the jb weld out. Lasted 7 years until someone hit my wife and totaled the car.

JB Weld is decent.  I had a blow off valve JB welded to an upper intercooler pipe that saw 18psi quite often. It held for years until the engine blew and it was hauled to the wrecking yard.

I have made some good repairs with Brownells Acraglass as well because I always have some on hand.

Posted Via AR15.Com Mobile