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Jan 20, 2019 | 07:20 PM

#31

FortyNiner

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Joined: Jun 2011

Posts: 4,995

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From: u-rah-rah Wisconsin

Hand turning should produce some amount of suction when covering a plug hole with your thumb.

Jan 21, 2019 | 07:04 AM

#32

raytasch

Believe Nothing

Joined: Jun 2004

Posts: 7,514

Likes: 398

From: W. Central FL.

Quote:

Originally Posted by Crownvicguy

Pertaining to your compression comment. I put marvel in the cylinders like 3 weeks ago (three drops each) and put the old plugs back in. Today i put new plugs in (slowly putting fresh new parts on it). I noticed when i rotate the engine by hand by the fan, i feel no suction or blast of air coming out of the spark plug hole (when my finger is covering the hole.....)
1. Does manually turning the engine by the fan not produce this?
2. Does this mean stuck valves?
3. When you look straight into the plug hole , is that a valve, and if so should i see it move when i rotate the engine?
4. Im going to purchase a compression tester gauge. Does the engine have to turn fast for it to read right? Or will it work by hand turning it.

1. An engine in good condition will produce compression when turning slowly.
2. You possibly have one or more stuck valves.
3. Valves are visible thru the spark plug hole.
4.An engine must be at near operating temperature, throttle blocked open, all plugs out, and cranked at starter speed for a compression test to be meaningful. Until these conditions are met, the thumb over the spark plug hole will tell you if you have compression or not.