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A Compression Tester That Holds Up

This is the Actron CP7828A Professional Compression Tester. It is used to test the amount of compression per square inch that is in the piston cylinder of an internal combustion engine, i.e., gas, diesel, propane, etc. If you work on car engines, especially older ones, it is a must-have tool if your engine is smoking or running poorly. Plus, it can give you specific information for diagnosing certain problems.

I am in the process of trying to bring back to life an old 1958 Dodge Power Wagon that has not run in some 15 years. Before going any further, I removed the spark plugs and sprayed a good lubricant into each cylinder and let it sit a few days to make sure that any rust deposits are freed up as best as possible before turning the engine over. Next, I will hand turn the engine crankshaft to make sure it isn’t “froze” up. The next step is where the compression tester is used.

This tester comes with different attachments that match up with the size and threads that are exactly the same as your spark plug size. Simply match it up, attach to the hose assembly with an 11/16” end wrench, screw it by hand into the spark plug hole, then attach the gauge (the gauge attaches by quick disconnect just like an air hose does). The engine must turn at least 6 revolutions to get a good reading, so make sure you have good battery power and a working starter on the vehicle. Repeat this process for each cylinder.

This tool can be used for different applications because of the different spark plug hole adapters. That is a real bonus. I am not real crazy about the stiffness of the hose for getting into tight spots, but that would be the only minor complaint I can think of. Overall, it is an excellent tester. Over the years I have used several different types of compression testers and this gem is the only one I would continue to use. It hangs on my wall of “the stuff I like.”

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Joe Anderson
Lifelong Shade Tree Mechanic, Grease Monkey, Gear Head, Knuckle Buster. Loves bringing old, dead, forgotten treasures back to life.
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