Can JB Weld fix a cracked cylinder head? See the proof!!


You know I’ve always heard that JB Weld can fix a cracked engine block or a cracked cylinder head But I’ve never seen it done And I don’t know if you have either but today we’re going to find out once and for all if JB Weld is up to the task of fixing a cracked cylinder head. There’s nothing wrong with the cylinder head on this lawnmower engine But I’m going to go ahead and basically simulate having a crack I’m going to take a cutting blade out and cut through this cylinder head, and then fill it with JB Weld, allow it to dry for 24 hours Reattach the cylinder head, and then see if it will take the pressure and the heat Additionally I have a hole in this gas tank that goes to this lawnmower I’m going to hold it up here and as I tilt it forward Gasoline is going to start to ooze out of it. I’ve got a pretty good-sized hole right up in here You can see it pours out quickly and JB weld is supposed to be resistant to gasoline So we’re going to find out if JB Weld can also fix this gas tank while we’re at it The first thing I want to do before I Cut into this cylinder head is to go ahead and clean up a lot of this buildup so I’m going to use some carburetor cleaner This is definitely clean enough, so what I’m going to do now is just cut through part of this cylinder head, and then apply some JB Weld So as you can see I’ve made a really big gash in this cylinder head and it’s so big I can easily slide a zip tie through it and This is going to be a true test for JB Weld to see if it can patch up this hole In order to make this cylinder head repair the first thing we need to do is to go ahead and bevel out on each side of this of This cut in order for the JB weld to have something to hang on to and we’re going to rough this surface up a bit Okay, as you can see there’s clearly a hole, and I’ve went ahead and beveled out around this this long gash And now what I’m going to do is mix up the JB Weld and go ahead and begin applying it into this crack JB Weld comes in… for those who have never used it comes in two different tubes and You just basically mix fifty-fifty And so what we want to do is just work this into the crack, just sort of pushing down on it And we’ll flip it over in a minute, and we’ll see if it’s if it’s flowing into the crack Again, we’re just sort of trying to massage it into the crack and this stuff is going to want to flow on us This is what it looks like now. We’ll check back in about 24 hours and see how it looks Okay, the JB weld has cured as you can see this is where the cut was at this is where I had beveled and there’s A slight indention there, but this should work very well, now I’m going to flip this cylinder head over real quick as you can see this is where the JB weld started to seep through So what I did was I put a little bit of tape down to keep it from leaking on through and draining if you will So right through here was where the crack was at and as you can see the JB weld has done a great job Of covering up this crack, now I have already pressure tested this tank. The way to pressure test the tank is to seal off the gas cap area where you add fuel and to basically put pressure through the… where it drains into the Carburetor, just add some air pressure to that to see if it holds. There was no more leaking air So I know this is a really tight seal, the question though is can it stand up to gasoline as JB Weld claims it can? Since the cylinder head came off of an engine that had low compression I want to go ahead and give this a really rigorous test I’m going to put this on a different engine that has very good compression, in fact over a hundred pounds of compression So this should give it a really good test. So you’re going to see me switch out mowers from the one I took this off of Okay, so we’ve got the cylinder head installed now I want to go and put this fuel tank on. As you can see right here. This is the JB weld This is where the crack was at right here like I said I pressure tested it I think this is going to hold fuel, so I’m gonna take a perfectly good fuel tank off of this machine and put the Repairing tank on to see if it’s going to hold Okay I’m going to spin the engine over five times Wow, that’s great compression, about 110 pounds of pressure. That is really putting this head to the test Okay, we’re about to do the ultimate test. One thing I’ve done is I’ve added an oil temperature gauge. This Mechanical Gauge, the sensor is fed right into the where the dipstick goes And I have created sort of a seal over here to keep anything from spewing out as the engine’s running So you will see this temperature rise. I’m expecting up to 160 – 180 degrees, that’s going to be our oil temperature Additionally what you’re going to see here is the temperature of the spot where you see the little laser dot. All I can say it’s very impressive results, the JB weld held up as you saw the temperatures exceeded 300 degrees Fahrenheit Additionally the oil temperature is about 190 degrees at times. I also want to say the fuel tank held up It’s leaking a little bit around the gas cap and not the actual crack itself So that’s a problem with my gas cap not not the repair, but I’m going to take the cylinder head off in a minute But if you heard there’s a little bit of a ticking sound in the motor and that was because the piston was coming in contact With the JB weld. One thing I should have done was sanded down the JB weld because it was a little too thick and Therefore the piston was hitting it. So I’ve just had this thing running at least 20 minutes and this engine runs at at least 3,000 RPMs so basically the piston has slapped into the JB weld at least 60,000 times in the last 20 minutes and it still held up despite all that impact. So all I can say is if JB weld can hold up in this engine, I’m pretty confident it can take on just about any task you have for it. I’m gonna spin the engine over five times Okay, guys looks like the JB Weld did a great job holding up. You can see some some carbon deposits on the JB weld, but there is absolutely no cracking, no issues with this at all. I am extremely impressed with what JB Weld was able to do. That tapping we heard Let’s take a look at the piston and see what it was, see where it was hitting at So you’ll notice here, there is a spot. That’s a lot lighter colored as well as here This is where the piston was coming in contact with the JB weld and as you can see the JB Weld held up really well, it did not do any damage to the JB Weld, obviously didn’t do any damage to the piston It was barely tapping it was just barely tapping the JB weld But it just goes to show the strength and durability of this product. Okay I went ahead and ground off some of the JB Weld I want to see if this is still going to work okay I think it will do just fine And I grounded off just because I want to get rid of that knock, so let’s see how it sounds and see if it’s back to normal Is that impressive or what? JB Weld Held up to a pretty tough test. You have to admit that cylinder had got pretty hot and it didn’t come apart Additionally the piston was slapping that cylinder head pretty hard And it slapped it about sixty thousand times and still did not break and so that was unplanned That was just my fault. I should have sanded that Excess JB weld off that cylinder head, so the piston wasn’t slapping it, so I admit I made a mistake there But anyway, all I can say is I am very impressed. The fuel tank held up as well, so in both tests It showed that it’s a good product. Just as a final reminder, I am not sponsored in any way by JB Weld or any of the manufacturers of the products that are right behind me here. These are all products that I purchased using my own personal funds. So my question to you today, the question today and I love reading your comments, is what have you used for making repairs? Have you used JB weld before? And is there a better product that you would like me to test for fixing a cracked or a cylinder head with a hole in it? Because I’m looking forward to testing the claims and testing the quality of these different products And you guys, I learn a lot from you You have a lot of great ideas, so I look forward to reading and responding to your comments Look forward to seeing next time on the next episode. Thank you

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