merc3.0 from 120 to 140

[watermellonI]

I pulle engine out of 19 cuddy, a 1990 merc, 3.0 I m chasing down a rattle in the motor, wrist pin or rod bearing, motor is on stand but i haven t got into it yet

my question is 2 parts a) how can i tell if this motor has been converted to a 140, and b) how difficult would it be to convert it to a 140, the motor has a fresh head, valves are clean as a whistle. so someone has done some work to it I noticed today the oil pan looks like its been removed before.

thx for all your input fellas, and btw, while its out i will be repairng tansom.

 

[Bondo]

Re: merc3.0 from 120 to 140

Hmmmmmmm,.......... I'm under the impression that All of the 3.0ls Are 140hp,.......
The 2.5l motors are 120hp...........

Other than Mercruiser changing the Advertized HP#s for whatever Reasons,.....
The 3.0ls are pretty much All the same motors......

 

[watermellonI]

Re: merc3.0 from 120 to 140

ok thx bondo, found rattle and knock btw, #1 piston wristpin overheated, froze the oil ring, and had begun to melt the piston.

 

[traveling man]

Re: merc3.0 from 120 to 140

There is 2 different 3.0 liters. 3.0L or 3.0LX. The difference betwen the 2 is the exhaust system. The LX is 140 horse.