3.0 mercruiser compression

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Fish Head

Cadet
Joined
Feb 6, 2002
Messages
22
I have never owned a I/O before and am cosidering a 18 ft. Cobia Bowrider with a 1991 mercruiser 3.0 and Alpha one out drive. The Head has been redone,carb rebuilt,new elbow,and manifolds. Work has been done by a dealer. What is considered a good pressure rating for a compression test on an inboard?Anything I should check out on the outdrive other than the oil? Any suggestions or advice appreciated.
 
O

ODDD1

Lieutenant Junior Grade
Joined
Jan 23, 2001
Messages
1,054
Re: 3.0 mercruiser compression

Anything over 140 psi cold would be acceptable....gearlube should be clear,when water testing the boat, turn the drive side to side while listening for rumbly noises..an indication of u joint/gimbal bearing that have been wet...depending on loaded weight of boat, would expect 40 mph out of it....
 
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