Cracked weld in my coolant tank. JB Weld OK for a bit?

Technical and Repair Discussions

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PostPosted: Thu Aug 11, 2016 1:25 pm
The tank cracked due to a weird vertical wreck where the tail section flapped down onto the tank from above. It's a very narrow crack in the middle of the weld about 3" long.

I'll probably get it re-welded but if I can't get that done in time for the next race, would JB Weld hold for a weekend?

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PostPosted: Thu Aug 11, 2016 9:49 pm
JB Weld is a great product for shear stress applications in stable temperature locations. I'm not sure I would trust it for non shear pressure retention over multiple heat cycles in a environment that this application would require. Could work but I wouldn't risk my weekend hoping it would hold.

At the very least bend a piece of metal longer than the split at 90 degrees then attach it to the tank using JB Weld so the stress on the repair is in shear in two directions.

(Personally I would take it to my neighbor who owns a fabricating shop and could have saved the titanic by welding wet toilet paper in the hole, but clearly you lack that option)

Clearly an opinion as I have never tried it, good luck
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PostPosted: Sat Aug 13, 2016 8:50 pm
I had this happened twice (arggH!) and used an epoxy designed for wet applications (emergency fix at the track.) It hardened sufficiently within a hour to get through the weekend (only a minor drip came through and it survived a couple of weekends until I got the tank replaced once, and repaired another time.). It comes in a roll (sort of a fat "Tootsie Roll" looking affair). You cut off a piece with a knife then knead it to blend the two parts together. I pressed it over crack in the aluminum weld bead (the problem area), overlapping at least an inch in all directions.
Bob Breton - SRF 51 - San Francisco Region
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PostPosted: Sun Aug 14, 2016 12:31 pm
breton wrote:I had this happened twice (arggH!) and used an epoxy designed for wet applications (emergency fix at the track.) It hardened sufficiently within a hour to get through the weekend (only a minor drip came through and it survived a couple of weekends until I got the tank replaced once, and repaired another time.). It comes in a roll (sort of a fat "Tootsie Roll" looking affair). You cut off a piece with a knife then knead it to blend the two parts together. I pressed it over crack in the aluminum weld bead (the problem area), overlapping at least an inch in all directions.


Hey, Bob, what's the brand name of that epoxy? Sounds like handy stuff to keep around.

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PostPosted: Sun Aug 14, 2016 3:27 pm
Curious about how many others have experienced cracks in these tanks? We've cracked two within the last year. These are not cheap to replace. Any thoughts about how to prevent this problem?

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PostPosted: Sun Aug 14, 2016 4:50 pm
I've had the same tank for 16 years and never had it leak.

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PostPosted: Mon Aug 15, 2016 1:33 pm
Mine did this Saturday at Grattan Majors, after qualifying, while I was idling my way to impound. Water temp had reached only 187 while I waited for traffic. Then, poof, steam wafted over my head.
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PostPosted: Mon Aug 15, 2016 2:02 pm
Ha! Some thing happened to me at the exact same place - crack in the weld... Luckily there was someone at the track that could weld it (They could see the desperation on my face so it was not cheap :o )
Jerry Aplass SRF #204
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PostPosted: Mon Aug 15, 2016 5:28 pm
Exactly the same crack we just had.
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PostPosted: Mon Aug 15, 2016 6:10 pm
Lee Spuhler wrote:JB Weld is a great product for shear stress applications in stable temperature locations. I'm not sure I would trust it for non shear pressure retention over multiple heat cycles in a environment that this application would require. Could work but I wouldn't risk my weekend hoping it would hold.

At the very least bend a piece of metal longer than the split at 90 degrees then attach it to the tank using JB Weld so the stress on the repair is in shear in two directions.

(Personally I would take it to my neighbor who owns a fabricating shop and could have saved the titanic by welding wet toilet paper in the hole, but clearly you lack that option)

Clearly an opinion as I have never tried it, good luck


I think the 90 degree angle is the problem with the weld in the first place. Seems like I read somewhere that is why most pressure tanks have rounded edges.
Dave Harriman
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