Mechanic breaks down what a head gasket is—and why they fail

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‘We actually had a Honda in here last week’: Mechanic breaks down what a head gasket is—and why they fail

'Head gasket about a $30 part but thousands to repair. The worst issue with your car to have.'


Eric Webb


Posted on Mar 24, 2024   Updated on Mar 24, 2024, 3:39 pm CDT

Look, some people know what’s happening under the hood of their car. But for the rest of us, all those parts just look like jumbles of metal and plastic.

That’s why it’s so nice when experts like Accurate Automotive mechanic shop in Colorado (@accurateautoinc) demystify those inner workings for us normies on TikTok. The shop shares all kinds of car knowledge, like the best vehicles for Uber drivers, with their videos often going viral. 

Earlier this month, an Accurate Automotive mechanic named Kelly answered a burning question: What’s a head gasket? The video explanation has 99,000 views and almost 2,400 likes.

So, what is a head gasket really?

As Kelly explained, the head gasket is a main component of your engine that goes between the block, or the bottom part of your engine, and the cylinder head, which is the top part.

“It seals the compression, oil, and coolant, all in the same gasket,” he said in the video.

Kelly continued, “We actually had a Honda in here last week. It had low compression, because the cylinder head gasket wasn’t sealing properly, and it wouldn’t start the car.”

One commenter wrote, “What is Head gasket? It’s the words you don’t want your mechanic … to tell you about your car problem.” Another commenter replied, “mine cost 2.4k to fix which wasn’t as bad as I thought it would be tbh.”

Another viewer wrote, “a head gasket is the most scary word a subaru driver will ever hear.”

“I want a car invented with no head gasket and no timing chain,” someone else commented.

“Head gasket can cause overheating whenever it gets damaged. it is very important to make sure you have … water/fluid in the water/fluid tank else it will get damaged,” a comment read.

“Expensive to replace. Blew one on my old Subaru (97) at 350k km. Sold the car to an old friend who did the work himself and the car now is well over 500k,” one person recounted.

“Head gasket about a $30 part but thousands to repair. The worst issue with your car to have,” a viewer commented.

@accurateautoinc What is a head gasket? #headgasket #mechanic #autorepair #auto #cars #fyp ♬ original sound – AccurateAuto

“Not a Honda I thought it was a good car ummm,” someone commented. Another viewer replied, “they are but no car is immune to that issue. it depends a lot if the car was new or used when you bought it. mine was used so the parts were getting bad.”

As auto repair company Firestone explained about the head gasket on their website: “Simply put, these unsung heroes make everything work and prevent your engine from destroying itself. All the while, extreme heat, pressure, and temperature fluctuations try to rip them apart.”

Modern head gaskets are usually made with multiple layers of steel, which helps them keep intact as they bear pressure, heat, and thermal expansion, according to Firestone.

And according to auto manual company Haynes, “Typically head gaskets fail when the cylinder head and the engine block expand at different rates as the engine is warming up, and the gasket can’t seal the newly expanded gap.”

Haynes outlined a few signs that your head gasket might be having a bad day: overheating, loss of power, oil contamination, white smoke coming out of the exhaust, or an external leak of fluids.

As for why replacing a head gasket can be so pricey, the part isn’t expensive, but the labor involved in dismantling and reassembling the engine is high, Haynes wrote.

The Daily Dot reached out to Accurate Automotive via email. 

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*First Published: Mar 24, 2024, 6:00 pm CDT