J-B Weld 2120 Radiator Repair Kit

It works, if done correctly. Most important is making use of the mix within a minute. I benefitted from reading these reviews, learning how quickly it begins to set and the suggestion to mix only a small amount. I mixed four servings and still have half left over. I realized when working with my first mix, how quickly it sets, that its a setup for failure to mix the full amount of black and clear fluids as instructed in their package, for it's much more adhesive than what can be worked with effectively before it begins to set. Cutting off a small corner of each sealed package, I squeezed out a small amount from each onto a piece of cardboard - no bigger than a dime, keeping them separate from each other. This gave me time to wipe off the package corner and fold it over a couple times to seal it. Kept separate, the chemical action had not begun until I mixed the two with a popsicle stick. Both are quite fluid and spread out when squeeze out, so give them room to spread and not make contact. It's easy enough to see when there are about equal amounts, adding more to one or the other to make them look equal. It's an advantage not to use too much. My cardboard piece was the size of a business card, stiff enough where I could hold it flat, mix and scrape off the stick on the card edge and work that mix into the whole amount. Because one is black, the other clear, it's easy to see and judge how the two mix. Using the brush, I brushed it into the prepared surface, kind of scrubbing it in to invite the paste to mix with the radiator plastic, leveled it off with the brush, applied the precut piece of fiberglass mesh, then brushed a coat of the mix over the fiberglass. By this time, it was becoming obvious the mix was hardening and would no longer be as binding. Knowing I had planned to apply additional coats, I stopped working with it and let it set for about 15 minutes. The brush also set up and was no longer usable, which added to the misrepresentation of the instructions. It's quite fluid when mixed, so if applying a thick coat to a vertical surface, it will drain down, adding to the challenge of keeping it in place, applying the fiberglass and coating that and keeping that covering in place, all before it begins to set. Knowing I had planned on additional coats, I could concentrate on placement. Inspecting that first application after it set, I could see where I could improve upon the coverage and mixed up another serving, applying it with my rubber gloved little finger. Because of how fluid the mix is at the beginning, it kind of self levels, though not applying too much for it to run down. Initial preparation of the plastic tank is critical. I sanded the area, beyond the crack to invite bonding. I had two cracks to fix, one about 3/4" long on the flat surface just below the upper hose connection tube, the other, an inch long on the top of the tube, from the opening coming in. After sanding, I used a wood burning tool - the V tip, to melt the crack line, about 1/16th of an inch deep, then melted the plastic over the crack. When hardened, I sanded that surface to roughen it. I had no engine oil to clean off, so it was just cleaning off the sanding dust with a alcohol moistened lint free rag. My fiberglass application on the round upper radiator tube, created a ridge where the fabric ended. After my first application, I filed that edge to be round for the hose to seal right and sealed that off with my additional finger applied coat. My patches are holding for a week, with no sign of failure, with both looking so well glued in - especially the edges, that they should be a permanent part of the plastic radiator.

Needed to repair plastic faring bracket in motorcycle. Thought fiberglass and mat would be strongest but it would have been $35 to buy small can of resin and mat. Found this and it worked exactly as expected. Mat was cut to size so it could wrap broken area. Mixed epoxy, put a coat on, pushed mat into wet epoxy, smoothed and covered with another layer. Within 10 minutes it was cured and solid. Expect it to be much stronger the original design. So there is no confusion, repair was made on inside of faring. Would not use if surface finish was important.

I hit a turkey, and it cracked the top of my radiator!!! I cant notice the crack by eye, nor can I feel it with a fingernail.. But it does lose and spurts out coolant.. I' on a fixed income and can't afford a new radiator right now.. We are going on a trip next week, so I have my fingers crossed!! Fist off, I went through the process, laid down the fiberglass cloth and it looks nice!! And not one leak or spot of dampness!! First, carefully cut the 2 bags apart from each other, but do not cut them open!!! Sand sand sand, do a nice job... Clean it and the surrounding area really good... Alcohol, etc.. I used windex.. Cleaned it, dried if.. Then cut and shape your fiberglass cloth to size.. You want plenty of overlap over the crack or hole.. This is getting things ready.. Knead the black bag, unopened.. Mine was quite hard, but loosened up after kneading.. Cut the corners of each bag, about a quarter inch.. Here's the trick!!! Squeeze out just enough to do the job!! And do not squeeze them out on top of each other or let the black pile touch the clear pile... Once they touch, it starts the curing process.. They call for 50-50 of each, black and clear.. I used less clear in the mix.. The clear makes it harden faster.. Know where you're gonna put it before all this and get the right tool to mix and the right tool to spread or apply it. I used an old ins card to smooth and spread and a popsicle stick, to mix the two, together!! Mix the amount you need, and apply, spread it.. Put it in the cracks or holes and spread it fairly smooth.. While still wet and tacky, put the cloth on and quickly press the cloth into the mixture.. Smooth it out with whatever tool your using. Now, the cloth and jb weld should be pretty tacky.. Mix up the rest of the batch, in equal parts and spread it on top of the cloth, and be sure to overlap the cloth and area... Keep working on it neatly till its too stiff to work with.. Less than a min.. I let my repair sit over night, with the radiator cap off and the coolant, below the repair area.. Checked today, and it was hard as a rock.. Topped off the coolant, ran the car in idle, dry as a bone.. Then took it for a ride!!! Perfect so far... Moral of the story, watch out for turkeys!! Plan your repair.. Get your mixer, spreaders, cloth cut to size etc... And prepping of the surface.. JB weld always performs the best, but its up to you, to take your time prepping, follow directions, and have everything you need ready, BEFORE you cut those bags open... The brush that comes with the kit, use it with your last coat... To spread and smooth.. If you use it first it will be junk in 30 seconds.. I will let everyone know how it all holds up.. New post and update.. It has been about 2 weeks now.. No leaks.. None And this was including a 600 mile + trip... It included, high speed, 80+ to hills to traffic jams...! Not a leak or drop.. In the amount of time since using JB, I probably have put about 1000 on, and it works perfectly... Aug.12, 2023. Update.. Many more miles added and no leak, not a drop!!

I purchased this to make temporary repairs to my mother's 2000 Chevy Tracker, the top 2-3 inches of the radiator is plastic, and somewhere along her way it developed a crack that was about an inch long and I wanted something that would hold so she could get around town if she needed to til I could get her new radiator delivered. This failed miserably, I was less than impressed when I opened the package and noticed that their patch material was about 60% unraveled in the box so more than half of the patch was just a ball of string, I decided to try it anyway as there was just enough of the patch left in one piece to actually cover the crack so I roughed up the area around the crack with a heavy grit sandpaper applied a layer of the JB Weld then worked the patch into said layer covering the crack, then laid another layer over that just enough to cover the patch material and let the car sit. the car wasn't driven for several days before this and I purposely let it sit for 3 days after applying the patch, started the car a few days later and the patch failed across the top I'd guess/estimate about 30-40% of the patch material didn't even adhere to the radiator plastic and when the coolant heated up it just peeled back and let water out anyway. TLDR: Don't waste your time or money on this product as it doesn't adhere and will just leak regardless.

I used this repair kit to fix a crack along the radiator mount on the radiator of my car. I ended up using two of these kits because when I used the first kit, it did not mix very well in the bag and solidified quicker than I could apply it. For the second kit, I mixed the two components of the kit outside of the bag, mixing them thoroughly for one minute then I applied the mix to the cracked area as quickly as possible. This material sets up quickly. (Before using this kit, I used a plastic welder first.) I did not like the fabric material that came with the kit. When using the first kit, the fabric would not adhere to the first layer of the welding kit components. The fabric also frayed repeatedly as I tried to cut it, then position it on my radiator. For the second kit, I attempted to use wire screening, but it had the same problem with getting it to stick to the first layer of the welding kit mix. The radiator was still on my car when I was making the repair. Maybe the fabric would have worked better if I had taken the radiator out of the car. After a week and a half, the radiator on my car does not appear to not be leaking from the crack I used this kit on.

Worked great to patch two pin hole leaks at the top of my radiator. Tip, using a piece of thin aluminum flat stock instead of the included fiberglass cloth will prevent the area of the leak from further flexing and eventually cracking the epoxied repair.

After reading reviews and watching youtube videos about using JB Weld products to patch radiators, mostly stories of failure, I tried my own approach which worked for about 300 miles. I had a 2.5 inch crack on top of my radiator—it was leaking so badly I could only drive about 20 minutes before I needed to add more coolant. My solution was five layers. First I prepared the crack, drilling a small hole on either end and widening it slightly, roughing up the area and cleaning it with rubbing alcohol. I first filled the crack with JB Weld cold steel epoxy. After four hours I roughed that layer up and then applied a JB Radiator kit—mixing half the stuff and brushing it on quickly (because it sets quickly) , laying down the fiber glass horizontally, then mixing the rest and covering it over a wide area. After an hour, I roughed up the second layer and spread another layer of the cold steel epoxy and let it set four hours. Then I added another JB Weld radiator kit for the fourth layer, with the fiber glass fabric stretched on a diagonal over the crack, and let the car sit overnight for the epoxy to cure. I drove it the next day and it did not leak but I noticed a single tiny air bubble in the top layer. So I added a fifth layer, cold steel epoxy again, and let it sit 24 hours. I then added K-Seal radiator sealant to the coolant. This patch held perfectly for about 300 miles but then started a small leak again. Fortunately this bought me enough time to do what I needed to do before disposing of the car. NOTE: My photo shows the fifth and final layer, this is JB Weld Cold Steel Epoxy, not the JB Radiator Repair kit layers which were layers two and four. The JB Radiator Repair kit is black, like tar.

First time using this product. It was simple to use. After sanding the leaky area and then cleaning it thoroughly, you just combine the 2 parts in a bag, mix together and then paste the soupy mixture in place. It dries quickly though, and as others mentioned, it does start to get hot after about one minute. I was done with my patch by then. About 4 hours later it was totally cured and my radiator no longer leaked. I then painted it with high heat spray paint and you can’t even tell a repair was made! This product saved me the time, aggravation and significant expense of buying and installing a new radiator. It could not have been easier. 5 stars for sure. Fantastic product.

Fantastic. This worked really well and hasn’t leaked after 2 months driving. Quick fix and long lasting solution.

It worked for my BMW E83. I had a pin hole on the aluminum radiator at fan side, on fluid tube between micro zig zac fins. I put half of this J-B glue on in a rush, hoping it would work. but it didn't. I checked myself for the reason why it didn't work, and concluded that 1. didn't make the area dry -at the time when I put the glue on there was wet fluid running, 2. didn't mix the glue thoroughly -I was afraid that I would have no time to put the glue on before it hardens as read of the comments by others. Before the 2nd time, remove the zig zac micro fins around the tube, made sure that no fluid running toward outside, then put just a little RTV SupperBlack first to seal the pin hold, wait for it cured, them take good time to mix the glue crazily -no worry about that it would harden in one minute, no it won't, at least in about 10 minute it won't. Put the well mixed glue on the area around, first layer then fiber, then then another layer then wait over night. The next morning it became hard and shine with nice color. More important, no leaking. As I like it, I bought another pack keeping it for spare.

I've received the item in bad condition and damaged

Worked perfectly for the minor repair on my motorcycle radiator after following the simple instructions before hand. Easy to use, 100% successes and well worth the wait from its USA seller.

Lo usé para reparar una pieza de línea de refrigerante a alta temperatura, funcionó muy bien pero ojo deje que curara 3 días a pesar de usar las cantidades correctas el tiempo de curado es tardado , en 3 días la dureza fue perfecta