How Long Will a 100% JB Weld Rod Last In a Running Engine?

When it comes to stresses inside an engine, there are few components that endure more than the connecting rod. As the link between the piston and the crank shaft, the connecting rod, known as a con rod or simply a rod to most, has a lot of responsibility and has to be pretty strong to remain in tact, even when things are running smoothly. Let there be a timing issue or a bearing failure and the stresses ramp way up, often causing a catastrophic failure and the rod be the only part that survives. We’ve seen plenty of race cars towed back from the top end with rods hanging out of the side of the block with the block itself obviously junk, the crank ruined and the piston no longer recognizable, yet the rod is just fine.
Obviously lawnmowers aren’t going to have the same kind of stresses on their rods as an all-out racing engine, but there’s still a lot of stress to deal with, so the idea of making a connecting rod completely out of JB Weld almost seems absurd, but this guy decided to give it a try, and surprisingly, it works… for a little bit at least.


With the JB Weld rod in place, the engine cranks up and runs for almost a minute and a half before shutting down. Taking a look inside the mower’s crankcase, the rod is completely destroyed, having broken into several small chunks of JB Weld and a couple of bolts. This isn’t really that surprising, though. To be honest, I didn’t expect it to even turn over before the rod broke, so for it to idle for over a minute was very impressive in my opinion.
Of course, this brings up the topic of what else could be made from JB weld to see if it can handle the stresses? A piston, perhaps, or maybe the crankshaft? There are plenty of components in an engine that could be made to try. Hopefully, somebody out there has the same idea we do!

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