# JB Weld SCREWED me with false advertising



## TheEgg (Oct 29, 2017)

I've made several attempts over the past 2-3 years to repair a coolant leak in a hard to reach area of a cracked engine block.

It kept failing and each time I kept taking it apart all over again thinking that I just needed to clean and scuff it better.

The product I used was ORIGINAL JB Weld which is rated for temperatures up to 550°F and recommended for automotive use.

Now I see they have a HIGH HEAT version that is also rated for 550°F. What gives? Well the High Heat packaging mentions that it will only withstand that temperature intermittently and that it can withstand up to 400°F continuously.

...


So the whole time...the WHOLE effin' time, the JB Weld that I've been using...that claims to withstand up to 550°F, can NOT withstand that temperature continuously??? Then what temperature IS it rated for continuously? It doesn't say. 

A reasonable person would assume that the advertised temperature IS continuous unless otherwise stated. Imagine buying a stove that can heat up to 400 degrees...but only for 10 minutes at a time.

I would have gladly chosen the High Heat version had I known what I know now. But the packaging on the original version had every indication that it would work. I had no idea there even WAS a High Heat version when this all started.

Right now I have a vehicle that I thoroughly cleaned, scuffed, and coated the hell out of with original JB Weld. If it leaks now, I'm in worse shape because it won't be a tiny hole anymore and would be leaking along the whole perimeter of the large surface area I covered.

Hopefully it will hold. Probably it will not. And likely because of the temperature conditions. Imagine all the unnecessary grief I could have been spared if I was able to choose the proper product from the beginning.

TL;DR JB Weld's packaging is misleading.


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## Tymbo (Jan 18, 2018)

A cracked engine block cannot be fixed with JB weld, no matter how well you prep it. Every time the block goes through a heat cycle, it will expand and contract, breaking the bond.


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## TheEgg (Oct 29, 2017)

Tymbo said:


> A cracked engine block cannot be fixed with JB weld, no matter how well you prep it. Every time the block goes through a heat cycle, it will expand and contract, breaking the bond.


If thats the case, then they're REALLY lying, because their website and packaging specifically says engine blocks.

https://www.jbweld.com/product/highheat-epoxy-putty


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## 3onthetree (Dec 7, 2018)

I think you have misunderstood their listed uses for "automotive" regardless of the marketing terms used. You could possibly repair a cracked metal trim piece or something more substantial if it were plastic. However, a _cast_ engine block crack can not be repaired with a magical fix. There has been a reason evident from the beginning of combustion engines, that because of the cost and difficulty, cracked engine blocks are useful as anchors.


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## Bigplanz (Apr 10, 2009)

JB Weld: friend of every used car lot in the country.


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## SeniorSitizen (Sep 10, 2012)

Yes, marketing, and you've been screwed of about 10 bucks and your time. That's really a pretty inexpensive lesson learned.


Now do a little research on stitch locking.


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## Oso954 (Jun 23, 2012)

> Hopefully it will hold. Probably it will not. And likely because of the temperature conditions. Imagine all the unnecessary grief I could have been spared if I was able to choose the proper product from the beginning.


Whether it is temperature, vibration, Mfg defect, road debris strike, or some other factor is hard to say, but the bottom line is stress cracked it. Some of these can be temporarily repaired with JB weld.

But there is no “proper product” to fix a cracked block permanently. Replacing the block (or the entire engine) is the only true fix.


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## TheEgg (Oct 29, 2017)

Oso954 said:


> Whether it is temperature, vibration, Mfg defect, road debris strike, or some other factor is hard to say, but the bottom line is stress cracked it. Some of these can be temporarily repaired with JB weld.
> 
> But there is no “proper product” to fix a cracked block permanently. Replacing the block (or the entire engine) is the only true fix.



Yeah. Its an old vehicle (not mine) and its time for a different one. If it gets this person through the winter I'd be satisfied. I'm a little bit relieved to learn that it wasn't my shoddy handiwork. I put a lot of time into trying to do the best job possible.


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## Rough Rooster (Feb 7, 2015)

Repaired an aluminum timing cover on a 302 Ford that had rotted away from galvanic corrosion in the water pump passage. It was done from the inside with a tapered hole using JB original. So far it has lasted 18 months. I am experimenting to see how long it will last.
Hole was about 1/2" in diameter after cleanup. Used LOTS of JB Weld.

RR :smile::smile:


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## lenaitch (Feb 10, 2014)

I don't want to sound like the thread police, but isn't a post that is solely about dissing a product considered inappropriate?


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## huesmann (Aug 18, 2011)

Rooster's post isn't dissing it.


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## Davejss (May 14, 2012)

Repairing a cracked engine block with JB Weld is like repairing a flat tire with a can of Fix-A-Flat.
It should get you back to the garage so you can do an actual repair.


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## lenaitch (Feb 10, 2014)

huesmann said:


> Rooster's post isn't dissing it.



I meant the OP topic.


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## ron45 (Feb 25, 2014)

Okay.

Engine blocks are not that much.

This one $695.00

https://www.google.com/search?q=eng...lAhXSTd8KHZOxDnYQsxh6BAgQEEY&biw=1920&bih=937


https://spprecision.com/products/ch...MI88Wa39zq5QIVEIvICh2UTw1NEAkYAiABEgLawPD_BwE


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## edfiero1 (Mar 6, 2017)

ron45 said:


> Okay.
> 
> Engine blocks are not that much.
> 
> ...


True,..... but the labor to remove the engine, and transfer all components to the new block and replace it is THIS...............................................................................................................................................................................................................................................................................much !!!


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## ron45 (Feb 25, 2014)

edfiero1 said:


> True,..... but the labor to remove the engine, and transfer all components to the new block and replace it is THIS...............................................................................................................................................................................................................................................................................much !!!


The egg said,

"" I've made several attempts over the past 2-3 years to repair a coolant leak in a hard to reach area of a cracked engine block.""

How much is this.?

If it was easy everybody and their Grandmother would do it.


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## ukrkoz (Dec 31, 2010)

https://www.google.com/search?sxsrf...hUKEwji7fHjyYDmAhVzLH0KHaoNC7AQ4dUDCAc&uact=5


This should have been done BEFORE attempting such repair and then getting upset with something. Basic research. Also, I know how to fix such things with resin but, it takes much more than just slapping some JB or else onto the crack.


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## Bigplanz (Apr 10, 2009)

As noted in the above link, JB Weld is a temporary fix. That is wby every bottom feeder used car lot in the country has a case or two in the back storage closet.


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## ktkelly (Apr 7, 2007)

JB has it's place.


Had a bell housing hit a rock and it busted off one of the dogs that the flywheel cover mounted to. A little JB build up, drill and tap a bolt hole, and it works as it should. JB is good for a no stress not so important job.



Never thought about using JB to attempt fixing a cracked block.


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## ukrkoz (Dec 31, 2010)

I can resin stress areas too. Not that hard to do, if you have access. Just needs to be done right. JB Weld is nothing but a 2 part resin. I work with resins since my childhood. And, as part of my profession. 

Btw, if you want REALLY good resin, look up Fabtech 2 part glue. Just don't go for 25 second one. It's done before you mixed it. 60 sec one works great. 

https://www.fabtechsystems.com/pluseries-60-second-adhesive-220ml.html


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## Bigplanz (Apr 10, 2009)

ktkelly said:


> JB has it's place.
> 
> 
> Had a bell housing hit a rock and it busted off one of the dogs that the flywheel cover mounted to. A little JB build up, drill and tap a bolt hole, and it works as it should. JB is good for a no stress not so important job.
> ...


It works fine for situations with no flexing or heat caused dynamic stress. Bell housing? Yeah, I can see how that would work. Engine block crack? No way.

I have used it before, and it has worked, within its limitations. I still have some here in the basement.


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## raylo32 (Nov 25, 2006)

I love JB Weld for a lot of uses but no way it will repair an engine block. Never would have occurred to me to try that. And always remember, this is the USA, where it is pretty much OK to make any false claims you want as long as it helps you sell stuff and make $$.


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