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Affordable Aircooled 911 Project: Diagnosing Engine Health with a Leakdown Tester

In this episode, I’ll be diagnosing the overall health of my engine using a leak down tester from Harbor Freight! Will it get expensive and need new rings? Headwork? Both?


A leak down test is like compression test, but better. Instead of just showing you how much compression you have, you can pinpoint where your engine is worn out; the intake valves, the exhaust valves, or blowby past the piston rings. The big thing we’ll be looking for is consistency across all the cylinders.

I know some of the numbers shown in this video may ‘scare’ some people into thinking this engine is junk, but please remember engines are often fine until the leak down numbers get into the 30% range. This is also a COLD engine. Reading would be higher if it was warm.


WARNING: I would AVOID the leak down tester shown in this video. It’s pretty obnoxious to use and you can only use it at 15PSI, which produces questionable data. I would strongly suggest buying a different leak down tester that can handle more PSI.

Stay tuned as I start to get further into the disassembly and begin to modify stuff.   It’s going to be awesome, eventually.

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