Need to Repair pin hole leak on my radiator

[GPintheMitten]

I have a pin hole leak near the top of my radiator on my Kubota B2620. The top of the radiator, where the leak is, is some sort of plastic.

Do you think if I drill it out to about 1/8" and put in some JB Weld, would it hold?

 

[Gary Fowler]

I think I would take a wire wheel on my grinder and rough up the area and reduce the thickness a bit but not all the way thru and then JBWELD it. Be sure to clean the area well with some Dawn dishwasher soap and water first then, dry it and just before applying the JBWELD, clean it well with some acetone to soften the plastic and remove any greasy residue.
Remember that JBWELD will creep on you so it needs to be flat where the repair is. You may need to apply a second layer to get the buildup needed if it creeps on you too much.

I have used it on a plastic diesel tank and it is still holding after 5 years but there is very little pressure on it as opposed to the 10-15 PSI or so on your tractor's radiator.
It is worth a try but if it doesn't work, a radiator shop might be able to make you a solid brass one for less than a Kubota plastic replacement. I did this on my John Deere garden tractor. It wasn't cheap, IIRC about $200, but it got rid of the plastic end pieces.

NOTE: This pin hole leak might be just part of a linear crack that may not be visible to the naked eye. I cant imagine plastic having a pinhole leak like a metal one might get from corrosion.

 

[TractorGuy]

Buy a new radiator! Engines are much more expensive.

 

[MMagis]

If you clean it well and rough it up, it’ll hold for a while. Maybe a long while, but it’s tough to tell. There’s no reason to go buying a new radiator just yet, it’s not like your engine is going to suddenly explode. The hole is at the top, there’s literally no way for the water to run low enough to cause an engine failure. Besides, I assume most here know how to read a temperature gauge.

 

[Coyote machine]

Can you show pics of exactly where the rad is leaking? Most plastic header rads end up being replaced by copper ones. Most fail at the gasket that seals the header to the core, though having a pinhole from a defect in the plastic header is a possibility too, I suppose.

 

[GPintheMitten]

Picture of radiator. The engine is cold and not running so no leak in the pictures.

 

[GPintheMitten]

Here's a close up. I can't see the pin hole.

 

[Billrog]

I would consider making a rubber washer and sticking a small sheet metal screw in the hole. I've had a roofing bolt in a tank on a compressor for the last ten yrs. and it still doesn't leak with up to 120# pressure. A short one with coarse threads would be the best.

 

[Travelover]

I'd do the JB Weld first. Pressure is less than 20 PSI and you've got a tiny surface area if you don't drill it out.

 

[Coyote machine]

I'd sand the area to give the JB Weld something to grip. If that doesn't work then a self tapping sheet metal screw with a rubber o-ring might be enough to seal it with JB Weld surrounding the screw and washer as a belt and suspenders approach.
Thanks for the pics, seems the end cap portion of the header has a hole in it, if I'm following where you indicated with your finger?

Usually those rads fail where the header is crimped to the core, as can be seen in your pics. This one might be saveable. Note: Some plastics can only be sealed with a plastic welder, but I think you can get around that here due to the small hole size.
When did you do your last coolant changeover/flush?