1995 mercruiser 3.0lx compression trouble s/n 371961

[thmlrmg]

ok to start with i sucked a screw in through the carb and in went all the way down to the #4 cylinder and destroyed the piston. Before anything I checked compression on all the cylinders and there was nothing. I removed the motor and completely rebuilt the motor with new pistons and everything. The head was bench tested ok and milled down flat. Now with the motor back in the boat and all new parts i still have no compression? With the #1 cylinder push rods disconnected to close both valves i have 50 psi of compression? Any help would be appreciated. thanks

 

[Alumarine]

Re: 1995 mercruiser 3.0lx compression trouble s/n 371961

Are you using the starter to turn the engine over when checking the compression?

 

[thmlrmg]

Re: 1995 mercruiser 3.0lx compression trouble s/n 371961

yeah, everything is in the boat and hooked up. I have a battery charger/starter hooked to the battery to make sure i have enough cranking amps.

 

[Alumarine]

Re: 1995 mercruiser 3.0lx compression trouble s/n 371961

I think your best bet is to do a leak down test to isolate the problem.

 

[thmlrmg]

Re: 1995 mercruiser 3.0lx compression trouble s/n 371961

will do, i will tomorrow until then any other input would be greatly appreciated

 

[Don S]

Re: 1995 mercruiser 3.0lx compression trouble s/n 371961

Are you sure you have the valves adjusted correctly?
If, when you started adjusting and wasn't on #1 TDC, then you won't get any compression.

PS, with both valves closed you won't get the proper compression either because you can't get air into the engine to comrpess.

 

[muc]

Re: 1995 mercruiser 3.0lx compression trouble s/n 371961

Sometimes it is hard to tell when you have reached zero lash.
I find it helps to spin the push rod with my fingers and when it gets hard to spin that is zero lash --- I think this is easier to feel than the up and down movement.
Good luck Muc