JB Weld Original Cold-Weld 8265-SUK Steel Reinforced Epoxy (5020 psi) I did some science to destructively test a join made using JB weld to see just how strong structurally adhesives are vs their claims. Interesting results.
There is a letter (not le--er) T in the alphabet. Please use it instead of the glottel stop. It's no wonder that Americans cannot understand the British (or is it Bri-ish) way of speech.
Just try listening to more British speakers, there are lots of good videos available. Their accent will get more easily comprehended the more you do this. They speak the way they speak, just as you do, you can't expect a change.
I’m an American and I always make fun of them for the lack of T’s. For example hearing then tell their kids to settle down is funny. (Se-uhl down) but we also replace the T’s with D’s when we say water. English is funny
@@ericsmith1086 Indeed! Listening to Americans speak, what often strikes me is the heavy rolling "R's", which sounds to me a bit similar to an Irishman speaking English, as opposed to Gaelic. I also find it amusing how New Yorkers truncate some words, so that "hammer" becomes hamma, or "give me" transforms to "gimme" for example. Yes dialects are interesting and British English is particularly interesting to me because a trained ear, one superior to mine, can accurately place a person's birthplace and social status the minute they utter a few words.
This is a true story: Way back when I was about 18 years old (around 1978 or so) I worked as a mechanic in a small (tin shed) mechanic shop. Most of our customers were lower income and we were always having to find ways to fix their cars on the cheap. Well, one day, this old man drove his old truck in with a water leak. I climbed up under it to see what the problem was and low and behold, he had a huge crack in the side of the engine block. If you added water, it just poured out the side. Clearly he needed a new engine. But sadly he didn't have two dimes to rub together. So I suggested to my boss that I try cleaning it up real good and putting some JB Weld on the crack. We figured nothing from nothing leaves nothing (that song just happened to be playing on the radio at the time) and we didn't see how it could make it worse. So I did. Well sir, believe it or not, it worked. For years we'd see that old man driving his old truck all over town with a free JB Weld repair. Yeah, we didn't charge him for the fix. You never know when you'll need some good Karma.
We smashed an aluminum oil pan on a chevy van. Had all the pieces and jb ed it back together held great . Same thing with my diet bike. Held for years.
dude so many people talk shit on me for using jb. i feel like its got its good and bad applications.i feel like alot of people dont understand that more prep=exponentially better result. ive used it successfully on cylinder head pitting, pvc pipe joint seal, black iron pipe crack (high heat)!!! and a bunch more than i csn remember. not to mention the clear stuff! im hoping itll work for hairline cracks on alloy wheel. :/
@@sbibbity_bobbity_bup I made some mess. Do you think it's good enough to connect two aluminum pipeline together or brazing them is good enough for AC on cooling coil sides? Both sides, input and output. I think they must hold the pressure around 300 psi
@eone2345, I haven't experimented with containing pressure using the thicker JB Weld that comes as the two separate tubes or any glue/epoxy. However, when dealing with a similar situation in the past, I found success in locating a pipe section with a slightly larger inside diameter than the outside of the broken pipe. Filling the larger section with the jb version that comes in two separate tubes that resemble toothpaste , the original i think? I slid it over the broken area after preheating the ends. Applying heat with a torch or heat gun can aid the curing process once the new pipe is in place. thanks to chatgpt for shortening my explanation lol
@@sbibbity_bobbity_bup Seems like our thought on it are just the same to use that sleeve and having you verified it, now I have some confidence. Hopefully it will works because I'm kinda short on budget currently, especially when it's not even the main components that needed fixing, I still have to overhaul the AC compressor itself to change the seal 😅 Have a good day mate. Thank you for your answer with tips and swift reply, I really appreciate it.
JB Weld is incredible. While active duty in the air force, we used EpiSeal 20/20 for recovery of damaged aircraft when time was a constraint. We applied a thin coat of the adhesive to each face and then laid a piece of cheesecloth over the adhesive. Worked the 20/20 through the cloth and then stuck the parts together with clamps. The cheesecloth maintained a thin bondline between the metal and never failed us.
Shear strength: 10/10. Compressive strength: 10/10 Tensile strength: 8/10 Adhesive strength: 9/10 Peeling strength: 3/10 Shock strength: 2/10. That's my rating from years of use and testing! Nothing else is close!
@@PureNationalism13 If the lid or door is not too heavy or gets slammed a lot, it will probably work. If it fails, no harm is done, just bolt the hinges on.
Went on a camping trip and while towing my camper, my radiator reservoir cracked and caused my car to overheat and my whole car would steam up. Radiator fluid leaked all over. Where I was camping at was 45min deep into the forest. Thankfully, I always prepared myself with a good toolbox with essential needs. I happened to have my plastic welding tool and hooked it up to my generator and spent some time welding the large crack. I made sure it was good and sealed and sanded it down a bit so the surface can bond better. Then I busted out the JB weld and pasted it all over the crack for extra reinforcement, i made sure the surface was clean and debri free. Its been 12 years and this thing still holds up like a champ.
The bonding strength can be improved somewhat by "roughing" the surfaces with an abrasive wheel. I use a 3M Paint and Rust Stripper abrasive wheel for gluing metals. I find JB Weld quite good.
For Automotive structural joints, often the choice is between a welded or a bonded (using adhesives) joint. However, with the adhesive joint there is usually a preload clamping device in place while the adhesives cure, many times rivets are used (sometimes spot welds), where they remain and are not removed. From a design standpoint we have different unknowns which factor into the quality (strength) of the joint in how it is loaded. With aluminum welding can reduce the maximum tensile strength in the welded zone (heat effected zone), but there are many variables as to the magnitude of this reduced strength such that the joint safety factor is increased to compensate. This can add weight, which is not beneficial in weight sensitive applications. The interesting thing with your demonstration is how the adhesive fails. The shear is not transmitted to any fastener, because there are none. But if there was a preload device than shear never would be transmitted to the clamping device, because the failure mode strength of the adhesive is so much greater than the preload the force, the fastener would just be overwhelm during failure. In other words, the failure mode is catastrophic and without warning, except of course for the cracking sound before the joint explodes. The better test would be for shear fatigue, because the joint surface area is so much greater with adhesives. So what would be the fatigue life loading and cycles between a common two row riveted lap joint one without adhesive and one with keeping everything else the same? As you mentioned the applications of adhesives are confines to relatively low temperatures as comparted to a welded joint. Although metals also exhibit a reduction in strength with temperature but at much higher temperatures as compared to adhesives.
Also good for body repairs, if you got a side panel that's rusting out you can just cut it with a grinder, and put a new piece of stainless there instead. Then Fill, sand, prime and paint.
Hi Jon, I really loved this video mate. Very informative and well presented. I have been using this stuff for years with simple electronic projects and had no idea how strong it was. Much appreciated.
Thanks for the excellent Demo mate. About five years ago I did a "temporary" repair on the exhaust manifold on my yacht's diesel engine with JB Weld. The stresses on the repair site were vibrational and extreme heat mostly and I have to say that JB Weld amazed me to the point that I am still waiting for it to fail.
It wouldn't break apart at all if it was welded properly. You would just crush it. People don't realize how dangerous these tests can be. could kill you tbh.
Had very good service using JB weld never failed me yet. Had a farmer friend repair an injection pump for diesel had cracked housing. Used JB to glue it together and its still running 20 years later
Yep...JB Weld is amazing stuff. I've used it for years repairing motorcycle cases, radiators, etc. Use common sense and prep surface well. It's not great for all applications but will usually get you by in a pinch until you have time for a proper repair. Although I repaired a leak in a KTM radiator 23 years ago and still perfect even with all the heat cycles.
My first real encounter with metal filled epoxy was in 1982 when on the road with my friend in his Datsun 510 (the "Rotsun"), my dad recused us by providing us with some Devcon product to repair a leaky radiator. He warned "you get that to a radiator shop ASAP". Turned out Jim never did any further repair, and sold the heap on several years later. Many a dirtbike has had engine cases put back together with JB Weld. I did this with my daughter's Honda she flicked into a boulder pile. Well I remember her thinking she'd killed it for good - hot oil on the rocks. We carefully collected all the pieces and that night I put Humpty Dumpty back together again. BTW, I've had very good results with "G-Flex" toughened epoxy for bonding various plastics. These joints need to be flexible and strong, if not as strong as the components. I use a variety of fillers, lately I tried the powdered PMMA that is used for artificial nails (!). I like it.
My dad has a hotrodded 510. ~270 hp in something that weighs about as much as an empty bubba of beer sure is fun. Great looking cars, they're like a stumpy version of the Hakosuka, it's just a shame the coupe didn't make it to North America (just the 2 door sedan). If he still had it, he might actually get decent money for it (compared to back in the day). Paint some strips and a #46 on the side and it's worth twice as much.
Used it on radiators all the time good as brazing it which in those days what was done with brass radiator. Now with plastic tanks it's disposable, but can't be repaired on the side of the road.
Wow what a Great video with so much information . This was definitely a TRUE test done the right way ! I truly appreciate you taking the time to preform this rest and then sharing it with us !
Awesome testing! I love it! It is - after all - still a type of glue. And glue has certain properties that make it excel in one load type and pretty much suck an another. All glues love shear forces. All glues hate tension. And worst of all: Peeling tendencies that combine tension with a stress riser. It is the task of the designer, to enable the first and prevent the latter. Your test is primarily shearing. The side pipes turn a little but then carry all the load on the inner edge. This is why you hardly see any peeling. If they were longer and would bend and turn under load, the peeling action would be much more pronounced.
Great result opening up many applications. Might be good to see how differences of extreme ambient temperatures affect the bond. Also removal of the zinc plating under the bonded surface.
I love JB Weld! I've used it for years and it's never let me down. I decided to watch some testing videos and this one is great! I was actually surprised that it held up under that much actual pressure. Gave you a like.
Just a quick note - I cannot in any way advise on individual projects. As with most things, engineering can sometimes be complicated an a one word answer is not applicable without knowing the project in detail. Refer to the caveats at @8:00
Great test Jon, I had a good chuckle when it let go! My test was not as in depth, but I could see that in my application and the saddle surface area a long with the rivet nuts, I'm confident all will hold up well. Thanks for your original vid. I no idea that the chassis could fail by the shifter. Really looking forward to your vid on the race cage. Ross
I found that JB Weld seemed to outperform pretty much every other epoxy that I've tried... and. of course, the fast-cure ones are pretty much 'plastic'... and, indeed, certain materials just don't 'wet' well, and are rather hard to get together. I had quite the argument, about 30 years ago, about adhesives, versus welding, for assembling a large opto-mechanical system, and I was convinced that the large wetted area of a tube mounted to a curved surface, would give large enough retention, without all of the issues that welding make for distortion and retained stress... sigh. But, even at that time, adhesives were being used for precision optics, using 'cure-in-place for accurate alignment/centration, and reduced cost. Great video!
Totally agree, and it's not even close! You just have to watch out for shock loads. You can adhere metal members together and can't pull them apart with a truck, but they will easily break apart with a light tap with a small hammer.
JB is one of a kind. I have made several fixes with it on many different materials over the years and only the ones in vehicles eventually failed. If it isn't subject to vibration it holds forever.
The cross member of the press trying to fly off was an eye opener - - there are occasional times when I'm leery running my own press - - adding top bars would perhaps offer some restraint - - I'm going to employ that idea when I think it might be helpful going forward. My personal experience with JB has ALWAYS exceeded my hopes, it is a crazy good product - I always keep an ample supply.
JB worked wonders for a hole patch on my MGB floor panels. I had two small pin hole rust stops, cleaned up and the stuff works as well as anything out there for that application.
That's very interesting! And great results! I'm investigating how to make a DIY oil filtration centrifuge (to filter alcohol from dissolved printing resin). Most demos I've seen show it made from steel and with welding. But since I have no welding skill or experience I'm considering alternatives. One is to make it out of plastic, and on paper it seems to be still possible (with appropriate sizes). But if JB-weld is this strong I'll be able to do it with stainless steel. There is only one rotating part (attached to a motor by a single axis). That part - inner spinning cylinder - has roughly cooking pot shape. The main difference (besides having no handles :)) is having a ridge partially narrowing the top circular opening. That ridge if cut just to fit inside the inner diameter of the top opening wouldn't be affected too much by the spinning force (I'm guestimating 3000~5000 RPMs), because the ridge ring would be held by the cylinder wall like by a hoop. Same goes for the bottom, which is going to be a full circular plate (with only few holes drilled in it - one for mounting the rod used for rotating it, and 2-3 drain holes for the dirty fluid). The bottom of the housing also have couple of specific circular ridges, to keep 3 separate areas - for clean fluid, for dirty fluid, and the inner most a hole for the rotation rod - but the housing wouldn't rotate so it doesn't need to be very strong. If this JB-weld works even half as good it would be few times stronger than what I need :)
It's strong, but it's shocking that the Titan sub's end caps were glued on with it. It would be interesting to know how it holds up over time of being under stress cycles like the sub was putting it through.
so imagine that over 5 tons of pressure were exerted on the sub at that time then understand the explosive forces produced in this video were exactly what has occurred inside the sub at the time of implosion.
@@godw1ll99 Not really, the forces there were much different after failure. Here the parts are moving freely in air, there 1.8% or so compressed water was filling basically a void.
That fracture was AWESOME 👌 thanks for sharing your fun bud glad the sims came out looking more trustworthy. Deformation discrepancy might be down to the fixing conditions in the sim not allowing the bottom beams to rotate so they react the moment differently🤷♂️. Awesome work.
Main reason is I never expected the thing to support 4.5 tons, so I under developed the sim so it seems. Even now its hard for me to get my head around. Yes the steel box did not deform like what the simulation said it would, infact it looks quite unaffected. I used standard materials but that steel box section is clearly stronger than the 220MPa I used on the simulation. The fixing didnt allow for rotation either which as you say would affect the stress at the bottom part. I don't think the 'epoxy' is the correct hardness either, it tends to stretch on the simulation where as you can see it doesn't do this in real life - it's extremely stiff. Good to do physical tests though as it highlights these mis-conceptions.
Thanks for this video, I love your explanation, especially with the explanations and models of a structural engineer. I have a blown out hole on a carbon ebike frame of 1 of 6 motor mounts. Since the manufacturer doesnt want anything to with garauantee I am going to dry this JB weld and drill a hole in the middle. I hope it works.
I have this really old single-cylinder air-cooled 2-stroke outboard motor with a broken skeg. I was planning on taking an original good condition Scag up to my old Junior High School metal shop class and have some new ones casted out of aluminum. Then I also got the idea to attempt to make the entire skeg and lower gearbox cover out of JB Weld. Mix it up, pour into a mold, sand down the mating surfaces and screw holes, do the little blue paint on it and see what happens. Your video just made me want to make that idea happen sooner.
JB Weld is always impressive in my experience. It will not do EVERYTHING a weld could do, but it's still very versatile. I have even had the putty perform well, but mainly used that in compression and put screws through it.
Wow great video... Not many focusing testing structural integrity of glue and epoxy. A other guy on RU-vid did a similar test for creating a drill sander. JB weld came out on top yet again as the best epoxy for the task.
Thanks for posting, a very interesting test. I have a little experience of bonded aluminium structures. I would comment that "Sand blasting" the adhered structure's faces to increase their bonded area may have improved the bond above what you managed to achieve. Chemically bonded structures are everywhere these days and offer some impressive options as a "Cold" joining medium.
Yep, most manufacturers I have spoken to suggest shot blasting, but don't really like the idea of heavy abrasion - I'd suggest they are worried about micro peeling leading to premature failure. One company suggested a smooth finish for that very purpose which is why I tried this test without a mechanical key. I was shocked the glue held up to very near the advertised strength. As I mentioned there are certainly caveats to using glues but I'm certainly going to be using them more and more, because in some cases they have clear advantages over welding.
@@JonHimself My own experience is with aluminium racing car tubs. The addition of solid rivets aids the resistance to peeling. In most cases, the material around the joint fails long before the bonded / riveted joint. I'm looking forward to see how you employ this newly gained knowledge to your projects! 👍👍.
@@speedfinder1 yep mechanical fixings are essential, I'm going to use them in the final design I am working on the the Esprit gear lever re-enforcement.... more to follow
Very impressed with your meticulous technique. For a future project, it would be very interesting to contrast compare these results (JB weld) to a few other scenarios, such as welding or bolting these pieces together. A lot of car reviewers mention how many cars are replacing welding with structural adhesives, so it might be interesting to compare the failure characteristics of those two scenarios.
Great video, I've been enjoying your scanning videos for a while now, and saw this whilst scrolling through. I've been thinking of using jb weld as a liquid shim. As a bonus it's good to see how well it adhears to simply preped metal.
yep its outrageous how well it bonds - I've not tested its crush resistance yet so it depends how much load you wanna put on it, it's pretty versatile stuff.
We use an epoxy at work called metalset but we have used JB weld in the past. If you drill holes through the glue section on both pieces and allow the glue to pass through and sag while it's curing it holds much better. It becomes more like a mechanical bond we've even reached in and smeared it where it has passed through the hole to give it even a better bond. We have noticed mixing thoroughly or not changes the bond significantly. We have checked out the glue they use to bond an aluminum car frame together. The name of the glue I can't remember at this point. Extremely expensive works very well but if you need something to hold together that well weld it.
I have used J B Weld to repair holes in small motors for many years I have two engines with 15 years of running and vibration with patches on them that as far as I can tell are as good as the day I put them on. Preparation is the key if you take the time to make sure the bonding surfaces are completely clean as you did in your test the stuff is pretty amazing, roughing the surfaces with sandpaper makes it even better. They have a putty mix called Steel Stik that is 4000 PSI and will withstand temperatures up to 300ºF. you can file drill tap it just like metal.
JB Weld is good stuff... I've always known that, but now I know HOW good it is... I have used it to bond some things in firearms with great success and now I have even more confidence that those bonds will endure.
Years ago I knew a guy who worked on the old Volkswagen Beetles. He had one that thres a rod and poked a 2 inch hole in the crank case. He replaced all the parts necessary and cleaned up the blodk in the ares of the hole. He thentaped some cardboard inside the block to cober the hole and patched it from the outside with JB Weld and It worked. The last time I saw the car about a year later it was still running with the patch in the blodk. JB Weld is tough stuff!
That’s awesome! I’ve never seen a test before that closely confirms it’s tensile strength. When using epoxies, I usually perform a mental calculation to estimate its suitability for the repair. Now I can really trust it. Time to go jb weld my bicycle back together. Very nice!
I hope you're joking. Epoxy is amazingly hard, approaching steel. But don't mount critical parts on your bike with it. (Unless it's composite carbon fiber or the like, then skuff up the sufaces before applying the epoxy.)
Yep....us old rednecks have figured out that if you clean it well....brake cleaner works great for most metal parts as a degreaser, especially the NON-FLAMMABLE brake cleaner....!!! and you have a good chance of one of 2 things happening 1 - your repair will last long enough to get the job done 2 - your repair will last until you've forgotten about it or - both.....lol Mix it well!!! MIND THE POT LIFE!!!!!
Used it to fix rust holes in a fuel tank once. JB weld is known as metal re-enforced epoxy. Kind of how hard angular aggerates enhances the sheer strength of concrete
I had a Ford v-6 some years ago where one of the spark plugs blew out. There was enough thread left in the aluminum head to feel threading the plug back in, but finger pressure was enough to pop it out. I put some JB Weld on the plug, threaded it in loosely, and removed the plug, which left a trace of the stuff on the head. After that cured for a day, I put more on the plug and threaded it back in - only finger tight. I let that set for a couple of days. After that, the engine started and ran normally. I traded the van off a few months later, with the engine still working normally. Never had any problems with the plug. I have used JB Weld for more than fifty years. It always works.
I was putting a thermostat in my van about 25-30 years ago and snapped off one of the ears on the cover 🤬. I couldn't afford the real Ford replacement at the time so I JB Welded the ear back on. This worked perfectly fine. I eventually found an affordable generic thermostat cover and replaced the JB Welded one but probably didn't need to.
Ive fixed many things permanently with good surface cleaning and proper application! This stuff really is quite amazing @ what it can hold up to if done correctly. Ive had things fail as well but you never know until you try!
I have a 20 year old two stroke Lawn Boy mower that still runs like a top but the deck is showing its age. I keep it repaired with JB Weld and it has never failed me. The stuff is great!!.
Interesting test, thanks! I'm not familiar with that simulation software, so I'm wondering if the force applied in the sim is tantamount to the gradual application of the press, or if it's simulating impact at that force (i.e. a sudden force vs. a gradual one).
Thanks for the video I had always heard this stuff works great if you clean steel mating parts well it sticks to fresh steel. I have a situation where someone drilled out a bolt hole for a shock mount larger then the bolt it would move up and down making a clunking sound when driving. Normally with this I just find a big washer that fits the new bolt with tight tolerance and weld it over the existing hole making the bolt fit tight again. The problem is the fuel filler hose runs right by this while I might be able to rig up a shield I rather not use a mig welder near a gas tank, and rubber filing hose. I'm going to try JB weld I will take a wire wheel and clean the steel on both mating surfaces. From what I seen in your test 4 tons should be more then enough to hold a shock mount on a Honda Pilot. I did notice the bolt got some JB weld on it as it tightened down I removed it again and cleaned it put some oil on the bolt keep the JB weld from welding the bolt into the hole. Probably could use some grease also.
7:39 "I didn't see the deformation it was warning me about" FYI Ansys autoscales your deformation to make it more clear, in your recording it says it was at 186x scale. You can change it to True Scale and it should look like what you physically saw
I used JB weld to repair aluminum railings with missing spindles at work. I tested it first on new extra pieces of square aluminum tubing. The aluminum surface is naturally oxidized, even when it is bright and shiny. So, I cleaned each bonding surface with a wire wheel, then glued and clamped the parts overnight. The next day I tried pulling the pieces apart. None of the glued joints broke. I could break pieces of the aluminum off, but the joints remained intact.
Been using JB for about 20 yrs, its awesome stuff, if i want a perm fix its my go to adhesive, they do many forms of it too, like JB Quick for a fast bond
JB Weld is an essential part of my "MacGyver Kit" aboard my sailboat, along with duct tape and wire ties. You can fix anything with JB Weld. My best example is a "temporary" fix to the timing case of a friend's Yanmar marine diesel. That "temporary" fix has held for over 14 years now. :-)
I'm not an engineer or professional but I put a diesel engine water pump back together with JB Weld that had broken into about 6 pieces. I put it back on the engine the next few days after it broke. Cranked it up and it n2ver needed to be exchanged for a new one. Though a new water pump was ordered it stayed on the shelf. That's amazing. If I were you I'd rough up the surfaces as adhesion would be much better.
I used to cure gauss sensors in JB Weld, then machine the JB weld in a threaded housing and then run the sensor in an elevated temperature environment. Never had a single one fail. Hundreds of them. It’s amazing stuff.
Nice test and impressive results. I would have liked you to compare to brazing or even soldering and of course mig/tig. The key to using adhesives is maximize surface area. I am amazed that weak bonds that are multiplied create great strength, like lots of little screws, but of course ultimately molecules are incredibly weak, but billions of them create very strong bonds.
Excellent test. I would love to see a comparison where you "rough up" the surfaces with a file or other to make deep scratches and see if there is any difference.
4 tons? That's just insane. I just repaired/covered a hole in my intake manifold using steel epoxy (JB weld equivalent) and was slightly worried if it would stand 20PSI of pressure and heat cycles. I guess no worries then huh =D Thanks for showing this in practice!
Thanks for sharing. I haven’t seen someone do such a shear test before. I suppose your setup has a bit of shear and tensile pressure given the force angles created. I am curious how well pure tensile strength is for jb weld. That’s where I have seen it fail sometimes, but I believe prep and applying it is very key for tensile strength success.
Me either which is why I did this test - I think people are like me and don't think it can withstand the forces, set up tests and cant break the stuff 😂 Tension test would be the next logical investigation but you need to prevent peel around he edges as the metal deforms.
I forget what car I was looking at but I know they used glue/epoxy to bond a lot of the body panels together. I think they found they could use thinner metal (lighter) than would be needed for the same strength using spot welds or pinch/crimp welds. It also allows for bonding dissimilar materials together (IIRC) like carbon fiber or fiberglass to metal. JB weld is some amazing stuff. I had a fairly decent size crack on the oil pan of my car & could not find a replacement for over 6+ months, so I emptied it of oil, cleaned it like 4-5x with solvent, used 40 or 60 grit sand paper to rough up an area 2-3" on either side of the crack (from all edges), cleaned it with acetone very well, then covered it with JB weld original. It's held since 2008 on an aluminum pan that gets pretty hot! I was told over & over from mechanics that it would NEVER work let alone last.
I've used JB a couple of times on pinholes and deep rust pits on floor pans with very good results. Anyone have experience on cast iron exhaust manifolds with JB or can you recommend an alternative. Thanks
@@vicfelton3594 The JB weld will almost certainly fail after the car has been running for a little bit & the engine & exhaust get up to temp. At this point it's going to just cook the JB, possibly even starting a fire. If you need to fix a cast iron exhaust manifold then I'd suggest someone who is good at welding & if it can't be done then try brazing the crack.
If i remember correctly (been some years) there are some 3M Pads that promise structural cold "welding" that can also adhere to oily surfaces(!) without any cleanup. You can check them too.
Now imagine the strength if you had provided proper bond-line spacing (using sand, glass bead, etc.). The effect of that is staggering but you did a great bonding job at the end of the day.
I was concerned about that too. The clamps squeezing the bonding agent out of the joint was worrying. Glass bead would have improved the bond uniformity.
When I was 17, I skeptically used JB Weld to fix a crack in my radiator and it held for 2 years until I got a new car. This was also in 05 or 06, so I'm sure further improvements have made it even stronger.
Unless I'm mistaken, JB Weld is thermally rated for repairing exhaust manifolds. I'm not sure about a blast furnace, glory hole, or ceramic kiln, but it should do for nearly any mechanical weld up to any engine temperatures.
My dad had a service station back in the 60's and 70's. He had a tire balancing machine that wouldnt stay in place with drilling into concrete and adding leaded anchor bolts used at the time. One day an old mechanic came by and my dad asked him to look at the problem and see if he knew a better way. He just laughed and said go the the drug store and get a bottle of "Flour of Sulfer". My dad said he would. So the next day he found some and the old mechanic told him to put enough in an empty coffee can and heat it till it became liquid and then put a bolt with the head down ito the hole and pour that stuff into it. I helped my dad as a young kid with this project. Ill never forget the surprise on my dads face when it held up. Years later we moved to a new location. My job was to move everything. When I tried to remove those bolts by every method I could use, nothing worked. My dad when he saw all my efforts fail said" just cut the bolts off even with the floor. Thats some kind of strength. I dont even know if this stuff is still available. Oh and it stunk to high heaven when melting/heating it.
