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We’ve all wondered whether or not those parts-store head gasket sealers really work, but most of us aren’t crazy enough to try after hearing horror stories about clogged cooling systems and increased repair costs. Luckily, there are some people on the internet who are willing to risk their cars to find the truth. Popular DIY wrencher ChrisFix decided to take a Jaguar X-Type with a head gasket leak and test a sealer for two years and 10,000 miles, as a definitive test of sorts. 

ChrisFix is a major automotive repair Youtuber with an awe-inducing 8.41 million subscribers. He offers a variety of content, and he runs numerous practical auto repair and performance-enhancing experiments like lightweighting a BMW E46. Mysteriously, he has never purposely shown his face, and it’s a long-running joke that he won’t show his face, instead opting to wear a helmet at all times. 

This dude has credibility and the knowledge to test this kind of thing with some authority, and this is one of the best experiments I’ve seen about head gasket sealers. The only demerit I can offer is the ability to only test one form of sealer, but it would take more cars to test more sealers. Thanks to the pandemic, putting 10,000 miles on the single Jaguar test car was difficult enough, and the test was plenty illuminating.

I’ve heard all kinds of horror stories about head gasket sealers ultimately ruining engines that could have been saved. To make matters worse, the sealers did not even provide a temporary fix for folks who were hurting for cash. This seems to be true of the older generation of sealers, but the current crop of chemical companies making a variety of fix-all substances for cars seem to have cracked the code, according to ChrisFix.

Four types of head gasket sealers in front of an engine.
ChrisFix / Youtube

Chris displays sealers from CRC, Blue Devil, K-Seal, and Bar’s Leaks. It’s fascinating to see how different all of the repair liquids are in composition and thickness. Some use what amounts to liquid glass and others use fibers in a liquid. All of the sealers harden under extreme heat after the liquids evaporate. The reason for this is so the liquid can benignly exist in the cooling system without hardening and clogging the system, so it will only plug a leak when it encounters combustion, which provides the extreme heat needed to harden the concoction. This is shown in the video when Chris pours some out and heats it with a blowtorch.

Chris ended up using a fiber-based sealer instead of the glass because of how quickly his car overheated. Some sealers take longer than others to form a permanent seal, and even the one Chris chose required a hard driving cycle and nearly catastrophic overheat to make the fix permanent. It fixed itself in real time, which was cool to see. 

The fix held for two years and 10,000 miles but finally gave way at the very end of the test. Chris disassembled the finally defeated Jaguar and saw exactly how the sealer worked inside the engine. He cut the end tanks off of the radiator to verify that the sealer didn’t clog the small passageways of the core, which it did not. Shockingly, no traces of repair existed anywhere besides the site of the head gasket failure. For the right situation, these snake oil quick fixes might just get someone a little bit of extra life from their engine.

This solid bit of mythbusting is one of the more interesting tests I’ve seen. It cuts through anecdotes with evidence and testing, so if anyone wants to try this fix before spending big money on what amounts to an engine overhaul, it seems to be an optional path to take. Just know that it’s still not a permanent solution.

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