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COMPRESSION TEST PROCEDURE

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brooksider7

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"Besides warming the engine, w

"Besides warming the engine, what is the correct procedure for checking engine compression. '95 225 ocean pro."
 
"Pull all plugs, good battery,

"Pull all plugs, good battery, screw in guage one hole at a time, crank over 2 or 3 revolutions each hole, remote starter is handy if you have one...or a second person to hit the key, record readings"
 
I believe that some manufactur

I believe that some manufacturers suggest grounding the spark plug wires when doing the compression test to prevent damage to the ignition system. It can also prevent accidental shocks.
 
"Yep, knew I forgot something.

"Yep, knew I forgot something..easiest way is to ground out the dead man kill switch killing spark to all cylinders."
 
"ground coils/e kill (teth

"ground coils/e kill (tether cord)
Screw the compression gauge into the plug hole.
open the throttle plate, and keep it at WOT (wide open throttle) for as long as you’re cranking.
It may take more than 4 revolutions to get a stable reading; crank for up to 10 seconds or until the needle stabilizes, whichever comes first.
If your battery is weak, the engine will turn over slower and give you lower readings
The last number the gauge jumps to is the compression for that cylinder
Repeat for each cylinder.
"wet test"
Add one capful (1-2 tablespoons) of oil to the cylinder with low compression
Let it sit for a minute to allow the oil to flow down and coat the sides of the cylinder and piston. If there are any gaps in the rings, the oil will seal them for the next few minutes.
Crank the engine for 4 revs, remembering to floor the throttle.
If the reading improved significantly (more than 30 psi), your rings are probably worn."
 
"If there is little or no impr

"If there is little or no improvement, take it to a marine mech that can perform a leak-down test to determine where the compression is escaping.
(A leak down test is more specific in pinpointing the condition of an engine.)"
 
"When testing compression, wat

"When testing compression, watch the gauge as you crank the engine. If the compression does not rise rapidly (50psi on first pulse,close to 100psi on second pulse), there is a problem. I crank for four pulses. If the compression does not reach an acceptable level over four cycles, you have low compression."
 
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