MTFCA Forum

Has anyone done a cylinder compression test recording electric starter vs crank psi? I'm losing my strength and find it hard to get over TDC even with the other plugs removed.

Jack up one wheel.

I believe you'd get good results using a starter. Most compression tests are done using a starter. Unless the compression is very low in all cylinders, you're looking for significantly different readings from cylinder to cylinder as much as for the peak pressure. I'd expect that testing each cylinder on the starter with the other 3 plugs still in place would give results very similar to a brisk manual cranking with the other 3 plugs out.

Just did a '15 yesterday - hand cranked, jacked up, plugs out & throttle wide open - I'm hitting 70 so I'm starting to feel it too !

When hand cranking have to spin the engine several revolutions to get a reading anywhere close to a starter. Starter should get you 50-60psi, pulling over 1/4 turn by hand will show bout 35, spinning by hand probably bout 45-50.

That's in the ballpark of my readings, Kevin !

Unless the reading is real low don’t get too fixated on the actual number. As Pat brought up you are looking for consistency between the cylinders.

Andy