J-B Weld ExtremeHeat

I purchased this item to repair an ash fettle in an old Vermont Castings wood burning stove, and it completely exceeded my expectations outlasting an entire season of direct fire contact. The fettle was cracked into two pieces and a prior owner had drilled two holes on either side and tried to connect it with an aluminum "bridge." The repair interfered with the door closing, so I needed to seamlessly "weld" the two cast iron sides back together. Before going through the trouble of taking it to a welder and paying to have it repaired properly, I took a chance on this J-B Weld ExtremeHeat. I used a Dremel tool with a fine grinding stone and cleaned up the two broken faces, along with about 1/4 inch of the area on either side of the crack. Following the advice of another review, I then took a cotter pin, stuck it into the chuck of my battery powered drill, and used that to thoroughly stir the J-B Weld in the container (this is a one-time use container... once opened and stirred, use it and toss the rest). After stirring for just under 2 minutes, I immediately applied it to the two surfaces, pieced them together, and then spread a little more on either side to ensure a supported bond. I then set the item on a flat piece of cardboard to cure for 2 days. (NOTE: you have to support the joint while curing, because the J-B Weld provides no structural support until completely cured. While wet, the item will just fall apart again if the pieces aren't otherwise held together.) When it was done, I replaced the fettle and lit the first fire of the season (crossing my fingers at the same time). Several months and probably 100+ fires later, the piece was still holding strong like the day I put it in. The fettle sits right against the fire, and many logs have rolled into it while it was extremely hot, with no noticeable damage whatsoever. I would absolutely recommend and use the J-B Weld ExtremeHeat again on future projects. As long as the proper preparation is done, and you follow the instructions, it's an awesome product!

I used JB Weld 36901 Extreme heat. to stop and exhaust manifold leak. A section of the gasket was missing. I just wanted a temp fix so it didn't damage the head on my tractor. This stuff worked great.

I bought this to patch a hole in my two stroke exhaust chambers. It worked well enough in the places that were completely dry and flat. Trouble is there arent many of those places on a two stroke exhaust. I think the oil soaked into the material. This stuff dries like a cement, so not great for my vibrating racket machine, but I think it held up well for what I asked. Took about 4-5 rides to start losing it. Was worth a try, probably work fine on a normal car exhaust. Maybe better if you can wrap with fiberglass. Dries quick, seems to be water based.

Since my old kitchen stove is my daily battlefield, I grabbed this after seeing a mom on Instagram patch a crack with it. I used it on a small crack in the cast iron part above the burner where grease always splashes. I cleaned the area, pressed the paste right into the line, then let it cure overnight before cooking breakfast. The next morning, I made eggs like usual and kept checking that spot every few minutes. Nothing bubbled, no weird smell, and the repair stayed solid even with the pan heating and cooling. I was really glad when my husband tried to wiggle the piece and it didn’t move at all.

Worked well for a cracked oil pan. I was able to ride this out for a week until I bought a new pan and installed it. Was very easy to mix and apply. Used a hair dryer to speed the curing process.

tl;dr - I applied this carefully over a crack in my exhaust manifold, the paste cracked in the same place. Tried again, cracked again. Long version: After 230k miles I ended up with a crack in the exhaust manifold of my Accord. It was a fine crack, and the manifold has long since been discontinued so it's an inordinately expensive part. The crack was on the back side of the manifold, next to the engine, so surface preparation was a nuisance but I did it very carefully. I applied the paste, let it set for a couple days (the instructions say one day), then started driving the car and the exhaust smell came back. I took off all the heat shields, put the inspection mirror behind there, and lo there was the crack. I emailed JB Weld and they were helpful. They mentioned the importance of surface preparation, but adhesion was not my problem. They were kind enough to forward my email to their chemist who suggested reapplying waiting 24 hours, then running the engine at idle for 30 minutes to let the paste cure that way. I followed all the instructions the letter, but when I started driving the car again the crack immediately reappeared. Now the paste does adhere well and withstands the heat well, and that's good. I'm sure in some situations this product is going to save people a lot of money, and since it's so very inexpensive compared to other ways of fixing the problem you should almost certainly try it. But this product doesn't seem to handle expansion well. Cracks appear in manifolds and fireboxes and so forth because they get hot and expand, so wherever you see the crack, that is exactly where the expansion happens. If that's where you put the paste and the paste doesn't expand well, the crack will come back. I wanted this to work and tried very hard. JB Well products are great and their people are very helpful. But a product intended to patch expansion cracks that cracks under expansion doesn't make a lot of sense.

Bought this due to the high temp claim. tried it on my small 24 hp kohler exhaust pipe that 90's angles into the muffler, sealing around the pipes. Firstly it completely separates sitting in the jar for more than a day. Once stirred up it turns to the gray color of standard jb weld but the consistency is more watery and drops instead of staying in place. i allowed more than 24 hours ( 1 week) to cure before running the mower. After a lawn cutting (about 45 min) I can see half of this jb weld has cracked and fallen off, the rest can be popped off easily by hand and I tried to layer after finding it failed the first time, that didn't make a difference. I will just end up actually welding the joints vs this junk. I was really hoping that this would work since their normal jb weld stuff works well. it also it turns white once a heat cycle has been applied to it, it doesn't stay gray in color.

Kneeling the 2-inch adapter into position, I utilized this product as a filler between two components that sit directly in the same cup without a divider. I wrapped a stainless shim around it to ensure a snug fit and secured everything with a clamp. So far, it handles thermal changes pretty well. I plan to see how it holds up after a week. I'm pleased with how helpful it’s been so far. An AI tool mentioned it has good adhesive qualities and durability, although I haven't tested those features myself yet.

kanon

Amazing result. Used on an old gas oven door. Unable to get parts to repair handle but this product did the trick. Very pleased.

I bought it to fill the gap developed in high pressure vessel..it is very good and handy in such situations..highly recommend.

Reparer un coude d’echapement sur un bateau le temps d’avoir la piece de rechange.

This glued me and my wifes marriage back together