'96 Mercruiser 3.0 LX Compression Numbers

snowbrd84

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Sep 23, 2012
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Bought a new boat and decided to check the compression today. My compression numbers on a cold engine were 125 160 150 150.

Carb needs to be rebuilt before I can run it to bring it up to operating temp to test again, but is that 125 likely to be an issue?
 

Bondo

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Carb needs to be rebuilt before I can run it to bring it up to operating temp to test again, but is that 125 likely to be an issue?

Naw,...... Recheck it after ya get it runnin',......
 

snowbrd84

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Sep 23, 2012
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Thanks for the reply. Going to pull the carb, rebuild, and give her another go.
 

snowbrd84

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Sep 23, 2012
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Rebuilt the carb and the thing fired right up and ran without needing to give it any throttle.

Let it run for 20 minutes, turned it off, pulled the plugs, tested from front to back and got 150/170/160/160

So the 125 went up to 150 with the engine warmed up and all looks good.
 

Scott Danforth

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Check your gauge, anything over 150 is suspect. If the gauge checks out, cylinder #2 has water in it
 

snowbrd84

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Sep 23, 2012
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I don't see any water in the oil and the spark plugs all looked good. Where could water be coming from?
 
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