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How to manually rotate omc 3.0?

D

daviddunivan

Contributing Member
What am I not seeing, a crank bolt. How does one rotate a 3.0 omc 1986 model without using the starter. Boat has been sitting a few years and motor is stuck. I have been soaking it thru the plug holes and would like to try and put some pressure on the crank to unstick the motor. Any help on this is great! Thanks
 
I've had some success just using the nut on the front of the alternator - just make sure the alt belt is nice and tight.
you might sort of help the crank pulley with your hand along with torque on the alt - just watch your fingers
 
hystat said:
I've had some success just using the nut on the front of the alternator - just make sure the alt belt is nice and tight.
you might sort of help the crank pulley with your hand along with torque on the alt - just watch your fingers
Click to expand...

Ya tried alt and water pump, they just spin on me both before crank will
 
are you sure the motor is what's stuck and not the sterndrive? or is the drive off?

if it is the engine that is stuck, and the pulleys are just slipping, that might be saving you from breaking a piston ring... patience..

some techs keep an old driveshaft from an outdrive to turn the motor via the coupler on the back
 
are you sure the motor is what's stuck and not the sterndrive? or is the drive off?

if it is the engine that is stuck, and the pulleys are just slipping, that might be saving you from breaking a piston ring... patience..
it's a very low comp engine... I can turn them usually just grabbing the belt and applying some downward pressure as I roll it

some techs keep an old driveshaft from an outdrive to turn the motor via the coupler on the back
 
The drive is on, prop spinning fine in neutral, cables are lil froze also. Trying to soak everything. May have tho pull drive to see for sure, just wish it was a way to manually rotate the engine with all hooked up. Its a used new to me project so I am trying to see where it stands
 
remove the battery from the boat. Put the plugs back in and drain the oil and fill it to the brim with kero or diesel, let sit for a week, or 2. Remove the drive and then try to spin it. I also try to spin the flywheel, and on sbc i don't try to spin it with crank bolt.. snap that and your in a world of hurt seen that happen.
 
daviddunivan said:
What am I not seeing, a crank bolt. How does one rotate a 3.0 omc 1986 model without using the starter. Boat has been sitting a few years and motor is stuck.
Click to expand...
I would NOT use the crankshaft bolt even if you do find it.
If you were to exceed the torque value, you may snap the bolt, then you'll be pulling the engine out for certain.

hystat said:
some might say try putting it in gear and turning the prop.... not my first choice though
Click to expand...
Yeah, the gear reduction would work against us for this!

island_boy said:
......... try a strap wrench on the crankshaft pully.
Click to expand...
... or the harmonic balancer! BINGO!
This is the safest method!

.
 
Ok, motor is free now, I put a flat bar in one of the slots in the balancer, came right loose with plugs out after siting last night. Water pump is froze up tho. No battery in body but did try one earlier and starter didn't turn motor. The mini part engages, but it won't engage the higher part. Pulled drive off and everything is like brand new, whole boat almost is, like out was used 10hrs then left out in the rain for the floor to rot away as it did. Maybe I should pull starter and try get that going now? Just trying see if its worth fixing up or parting out. Drive shifts great off the boat and is like new also. Shift and steering cable still not moving yet
 

  • Directions for a Throttle and Shift Cable Oiler

    You need a foot and a half of 3/8 ID reinforced plastic hose from Lowes, a tire valve, three hose clamps, a tire pump or small 12 volt air compressor with a gauge, and some MMO (Marvel Mystery Oil).

    Shave the tire valve down and clamp it in one end of the hose.

    1. Remove the fittings from one end of the cable.

    2. Put 3 inches of Marvel Mystery Oil in the hose for every 20 feet of cable length. Any light oil will work.

    3. Double clamp oil filled hose over cable.

    4. Apply and maintain 50 PSI of air to the tire chuck. DO NOT EXCEED 50 PSI.

    5. It will take 10 to 30 minutes for oil to appear at the other end, then your done. Have rags to catch the oil if your in a sensitive area.

    I suggest safety glasses just in case somethings blows apart, but I have never had a problem. My save rate on cables is about 75%. I did all my cables every 2 years as PM (preventative maintenance) but I was not on salt water.

    Copied and pasted here. I posted this on another site.
    ​
 
Cool, thanks.any ideas for the steering one? Throttle is fine now that shift one is temp unhooked. Got starter working and motor spinning, 150psi across all four. Outdrive back on. Just gotta get spark and clean fuel, carb probably needs rebuild and plan to try and run on a temp tank. Luckily antifreeze was in block and outdrive hoses. May try clean points etc tomorrow.
 
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