JB Weld on plastic radiator neck.

[Donald]

I have a crack in the plastic radiator neck. I have a new radiator but cannot get it installed for a few weeks and my Jeep is losing more AF that I would like to see. I was thinking of draining down the radiator a little, sanding the crack (or split), cleaning the applying some JB Weld. If it will slow down the leak (its at the very top) and buy me 2-3 weeks I will be happy.

 

[Trav]

Do just as you describe but use JB Water Weld (white) instead of the normal stuff,it should work with no problems for a long time.

 

[Autografe]

I did what I thought was a temporary fix on the radiator on my F-150 with JB. A seam was split at the bottom tank and the local radiator shop stated the don't do repairs anymore but the could order me a replacement for $60 more than I could get it the local parts store. Same radiator with plastic tanks. The all brass radiator's price approached the price of a new truck! A friend recommended JB Weld and having nothing to loose I gave it a shot. That was 4 years ago. Just make sure the area is really, really clean

 

[CharBaby]

This is great news as I have 2 neice/nephew that are in need of just that. Great to know!

 

[Quest]

a note here: you have to check the condition of the plastic radiator for if it has accumulated quite a bit of mileage and the ABS plastic body maybe on it's way out, then it makes no sense to patch it only to have it develop cracks again on some other parts of the radiator down the road.

I had similar situations on dad's old 323 ('88) , only to realise a few months down the road that it's getting so tired that it would develop some other cracks/leaks down the road. REplaced it with a Spectra Premium plastic rad and all was well again.

Q.

 

[SuperDave456]

I have friends who have also made permanent fixes to their radiators with JB weld.

I agree with the statement "Make sure the area is clean". Also give it at least 12 hours to dry/harden before going and testing it out, I'd prefer 24 hours, but that may be difficult if this is your daily driver.

 

[mechtech2]

That temporary JB Weld fix is likely to last for years.
Use JB Quick Weld so it doesn't run down while you wait for it to cure .
CLEAN an ROUGHEN the crack and surrounding area first!
For some cracks, a metal patch over the epoxy is best for strength.

 

[Trav]

I tried the JB Water Weld on a large 3/4" sprinkler pipe wet with water and it set in 30 min,no running.Its been holding up for a long time now,no leaks under even under water main pressure.They claim its ideal for radiator and fuel tanks.

Some info...
http://jbweld.net/products/water.php

 

[JimPghPA]

Clean the area with 91 percent alcohol that you get at the drug store. Then rough up the plastic with ScothcBrite general purpose grade (dark red). Then clean again with the 91 percent alcohol, then dry with hot air (a hair dryer works good).

Be sure to use the slow JB Weld. I tested the gray vs the white and the gray is a little stronger, but that was not for a radiator.

Give it at least 24 hours to dry and the ambient should be 75 F or above. The longer you let it set up the better. The best would be to give it seven days.

 

[mechtech2]

Why "be sure" to use the slow JB weld? JB Quick is perfect and preferred here.
Does your radiator get to 400+ deg F?

Scotchbrite is better than nothing, but is too smooth for good epoxy 'bite'. Good for initial cleaning, but roughen it up more for your best chances of success.

 

[JimPghPA]

Slow epoxy grabs into what ever you are bonding it to better. I have seen slow vs fast on many applications over the years and the slow always holds onto what ever it is applied to better than the fasst.

Also the slow JB has a higher temperature rating than the fast.

 

[mechtech2]

Yes, you are right - slow versions of the same products ARE better.

But if the fast product is more than enough, then usability is the prime concern.
Slow stuff runs all over and can be a real pain.
JB Quick is very good stuff.

 

[TedT]

When I fix tanks I use a JB layered with fiberglass cloth. I makes a very strong repair. I rough up the tank with 120 grit sand paper.

 

[Spazdog]

I drilled a tiny hole at the ends of the crack in hopes of preventing the crack from growing. Then JB Welded the crack

It worked well. Lasted another 6 or so months before it cracked somewhere else.

 

[XS650]

Originally Posted By: TedT
When I fix tanks I use a JB layered with fiberglass cloth. I makes a very strong repair. I rough up the tank with 120 grit sand paper.


That's what I do for a strong JB patch. Clean and roughen surface, Spread a thin layer of JB, work a piece of woven fiberglass cloth into the JB, then smooth the surface of the glass by spreading a thin layer of JB on top of the glass.

The thinner the JB layers, the stronger the patch, as long as the glass is completely filled with JB.