How To Test Compression On Lawn Mower ~ Gokart ~ Snowblower Engine

This is how to test a small engine for cylinder compression. A compression test can tell you if you need to rework the valves or install new piston rings.

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To test an engine for compression you will need an engine compression tester kit. This kit is easily found at most automotive stores. Generally a standard automotive engine compression test kit will work for a small gas engine as well.

To test your engine for compression first remove the spark plug and set it aside in a clean area.

Next find the fitting from your compression test kit that fits the spark plug hole in the engine.

Screw this in firmly but finger tight only. You do not want to mash the gasket.

Next attach the hose if one was included in your kit.

And finally attach the compression gauge itself.

If you have an electric start engine simply run the starter for a few seconds to get the compression reading of your engine.

If it is a manual start engine then pull the starter handle about five times in order to get a good reading on the gauge.

A good engine will give a compression reading of about 100 PSI on average. Lower than 60 or 70 PSI and the engine will be hard to nearly impossible to start.

The engine I am testing has only 30 PSI. This engine will never start again in its current condition. The valve seats are most likely very badly worn and need to be ground. The piston rings may also be badly worn. The only way to find out will be to open up this engine and examine it more closely.

Stay tuned for updates as I attempt to bring new life back into this old 1970s model Tecumseh engine.

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Troy
http://www.thedoityourselfworld.com
http://www.theoffgridproject.com

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