Need Help with 8.2 Mercruiser

[Dinows]

When we put the 36 Formula Cruiser in this year the warning came on at about 2800 reducing the power to one half (Twin Mercruiser 8.2 stern drive) Had a guy look at it and says we need a new engine as there is no compression in the two back cylinders on the port engine. Engine purrs like a kitten up to 2800 when the power is reduced, there is no knocking either. My Question. could the engine sound this good with 2 cylinder's not having any compression ??
Thanks For any help

 

[Scott06]

When we put the 36 Formula Cruiser in this year the warning came on at about 2800 reducing the power to one half (Twin Mercruiser 8.2 stern drive) Had a guy look at it and says we need a new engine as there is no compression in the two back cylinders on the port engine. Engine purrs like a kitten up to 2800 when the power is reduced, there is no knocking either. My Question. could the engine sound this good with 2 cylinder's not having any compression ??
Thanks For any help

Yes it could be. Basically will be down on power. What warning comes on? one thing that normally inhibits is the gearshift indicator seeing neutral.

there is zero compression in end cylinders? would think exhaust is leaking water and hanging up valves

@alldodge may have some thoughts too

 

[Bt Doctur]

get a better mechanic. could be just some leaking valves from water intrusion or holes in the piston at its worst. Only by removing the head will you be sure

 

[alldodge]

What is one of the motors serial number?

Don't see a warning sounding if motor has 2 bad cylinders, weak on power sure but warning, that's a hard one to understand. If power was weak on only one then you should be able to turn more RPM on the other

Get the motor scanned for codes

ECM may think the drive is in neutral. There is a in-gear switch on the shift plate. Disconnect the switch and see if warning goes away