Question about compression test result 97 Mercury V6 175hp (carbed)

Am close to buy this engine, but I didnt like the compression test result. - all cyl except 2 and 3 at port side had 120psi. -2 and 3 at port side had 140-145. Could it be some oil film left in 2 and 3 making higher value? The engine has been off the boat for a month, lying on the floor at the port side. Can get this great looking engine to a really good price, because it has an electric falt, but this compression test result make me put the "brake" on a little bit. . Would really some opinion from you experts here about the compression result.

Factory manual lists compression on this model as 110 to 135 with no more than a 15 pound variance.

There could be some carbon build-up in #2 and 3 that is causing the higher readings.

I personally wouldn't worry about the higher readings - but that's just me. The "electrical fault" you mention would be a far greater concern, depending on the asking price for the motor.

galamb said:

Factory manual lists compression on this model as 110 to 135 with no more than a 15 pound variance.

There could be some carbon build-up in #2 and 3 that is causing the higher readings.

I personally wouldn't worry about the higher readings - but that's just me. The "electrical fault" you mention would be a far greater concern, depending on the asking price for the motor.

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The electric fault is suddenly loss off spark on 3 of the cylinders, so I guess either stator fault or one of the switch-boxes "gone".That is easy to find out and not very costly to fix.
The price I can buy it for, is ONLY 6000 Norwegian kroner, that is about 730 dollars.
All instruments and top-mounted remote control included, and engine looks great with no corrosion anywhere,even the bottom yoke with mounting looks like its still new.

This is a object I guess its impossible to loose money on, or?

It a good deal and carbon build up is rare in a V-6 motor...

Engine has worked perfectly since new(same owner from new),yearly serviced by merc workshop , but as descriebed earlier in thread , it suddenly lost spark on one "bank". Doubt I have to change all electric parts, will do all tests with the DVA-adapter.

Took a chance,bought it , and will pick up the engine tomorrow and take in home to my garage.
Will do a new comp-test this weekend,upright this time,engine was laying down at the port side while first testing, will reply when done.

Thanks for link, what do you mean by wrong battery?

Stator was gone, got a used for only 80 dollars, engine now runs fine. Did a new comp test with the engine upright, all cylinders now ok(120-123 psi). Had to change the impeller to, since first comp test was done out of water, cools perfectly now. Turned out to be a really good deal buying this defect engine.

Thanks for the update. Not often we hear them which messes with my curiosity. Glad it is a simple, inexpensive happy ending.

I know about the battery issue, and my guess that is what happened, the rectifiers was already replaced, note on them says they were cleared out of factory march this year.