Manufacturer | JBWeld |
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Brand | J-B Weld |
Model | ExtremeHeat High Temperature Resistant Metallic Paste - 3 oz |
Product Dimensions | 4 x 4 x 5.2 cm; 86.18 Grams |
Item model number | 37901 |
Manufacturer Part Number | 37901 |
Folding | No |
Assembly Required | No |
Cover Included | Metallic Paste Repair Bottle 3 oz. |
Item Weight | 86.2 g |
J-B Weld 37901 ExtremeHeat High Temperature Resistant Metallic Paste - 3 oz
We don't know when or if this item will be back in stock.
- JB WELD EXTREME HEAT: Is formulated for repairs to iron, steel and metal in high temperature environments 1000°F / 538°C. Non-flammable, it contains no solvents or Volatile Organic Compounds (VOCs).
- THE ORIGINAL COLD WELD: JB Weld was developed as an alternative to torch welding. Designed to be effective in extreme environments, once it sets, it creates a permanent bond stronger than steel.
- SIMPLE TO USE: When fully cured, this metallic compound can be drilled, machined or sanded. It is great for repairing cracks, small gaps, seam connections or holes.
- VERSATILE & DEPENDABLE: Ideal for repair work on : exhaust manifolds, pipe connections, mufflers, catalytic converters, outdoor grills, fire boxes, gas and commercial furnaces and water heaters.
- DO IT YOURSELF: Big or small, you can DIY it with J-B. Our heavy duty adhesives repair & restore it right the first time. JB Weld delivers the legendary performance of the World's Strongest Bond.
Product information
Technical Details
Additional Information
ASIN | B01IBOBY74 |
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Customer Reviews |
4.2 out of 5 stars |
Date First Available | 21 July 2016 |
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Product description
J-B Weld ExtremeHeat is formulated to allow for repairs to iron, steel and metal in high temperature environments (2400°F / 1300°C). When fully cured, this metallic compound can be drilled, machined or sanded. It is great for repairing cracks, small gaps, seam connections or holes in exhaust manifolds, pipe connections, mufflers, catalytic converters, outdoor grills, fire boxes, gas and commercial furnaces and water heaters. This product is water based, non-flammable and contains no solvents or Volatile Organic Compounds (VOCs).

J-B Weld ExtremeHeat is formulated to allow for repairs to iron, steel and metal in high temperature environments (2400°F / 1300°C). When fully cured, this metallic compound can be drilled, machined or sanded.

It is great for repairing cracks, small gaps, seam connections or holes in exhaust manifolds, pipe connections, mufflers, catalytic converters, outdoor grills, fire boxes, gas and commercial furnaces and water heaters. This product is water based, non-flammable and contains no solvents or Volatile Organic Compounds (VOCs).
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Black RTV Silicone Sealant and Adhesive | KwikWeld Quick Setting Steel Reinforced Epoxy | TankWeld Metal Fuel Tank Repair Kit | SteelStik Steel Reinforced Epoxy Putty Stick | HighHeat 550 Degree Epoxy Putty Stick | |
Set Time | 1 Hour | 6 Minutes | 5 Minutes | 1 Hour | |
Feature | Mold and Mildew Resitant | Strength 2424 PSI | Petroleum Resistant, Stops Leaks, No Welding | Strength 900 PSI | 800 PSI at Room Temp. |
Cure Color | Black | Dark Gray | Dark Gray | Machine Gray |
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Most helpful customer reviews on Amazon.com


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.

Reviewed in the United States on 27 March 2018
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.



Reviewed in the United States on 9 January 2019



First impression of the product - very small. It says 3 ounces, but that's by weight, so obviously much smaller than 3 fluid ounces. That said, it also weighed less than 3 ounces on a tested scale even with the tub included, so I feel like I've been cheated.
Next point: it was a thick, dense paste, not the liquid you see on the videos. I would guess that was because the foil was damaged or not properly sealed. It was the correct color: separate tan/black before mixing and cement gray after, but mixing took quite a lot of effort, because it felt like nearly cured cement when mixing.
I did each step quickly, with no time between opening, mixing, and applying, so as not to allow it to cure prematurely. Being a nearly-dry cement consistency, It didn't want to adhere at all when applying it to the clean metal. I forced it to stay on by placing wood objects to keep it in place.
I waited around around 30 hours. My setup to keep things in place worked. The epoxy became completely dry, but not strong at all. The very light metal parts separated with almost no effort beyond the parts' own weight. I was attaching a very light heat shield to a vehicle floor. The heat shield had two good bolts already holding one side and middle; I was just attaching the other side where the stud had broken from the vehicle floor. The bond didn't even last long enough to give the vehicle a test drive. The epoxy was just barely stronger than a dried sand castle. Strong enough to hold its shape, but noting else. I can crumble it with my fingers despite it having been given time to dry completely.
In closing, this job took a lot of time and effort, and it was quite frustrating and discouraging to see the results. I will attempt to return this to the seller. Regular JB Weld has been good stuff, but this extreme heat version turned out to be a total failure.
