Rotating engine by hand >>

[SgtScrounge]

I need to determine if an engine is seized without engaging the starter. Can I rotate the engine by hand ?
The engine is a Mercruiser 250 cubic inch straight 6 .

Can I use a socket on the crankshaft pulley to rotate it, and if so, in what direction-clockwise or counter ?

 

[bigdaddypt]

Re: Rotating engine by hand >>

Yes you can...I've always rotated clockwise.

 

[Blk-n-Blu]

Re: Rotating engine by hand >>

If you remove the spark plugs you should be able to turn the motor over easily with the crank nut clockwise so as not to loosen the crank nut.

 

[ahendri]

Re: Rotating engine by hand >>

i also want to rotate my engine and i am new with very little knowledge about mechanics the crank nut is the one on the front of the motor on the lower pully of the belt?

 

[Doernuth]

Re: Rotating engine by hand >>

Did you have any luck? I am in the same situation at the moment. How did you get to the drive nut? mine is beind the motor mount and I cant get a socket into the narrow slot?

Any help would be usefull thanx!!!

 

[bucnon75]

Re: Rotating engine by hand >>

Yes, the nut on the center of the pulley should be turned.
My engine is a Merc 470. I use a 3/4-in socket, an extension and a 1/2-inch drive turning clockwise on the nut located dead center of the harmonic balancer..
You can remove the plugs to make it easier to turn over. Make sure the outdrive is in neutral and that the prop spins freely.

 

[Bt Doctur]

Re: Rotating engine by hand >>

Remove the drive first cause that could be whats seized.
just use the starter , either it turns or just goes CLUNK. Improperly done using the nose bolt
will cause it to shear off in the crank.
Remove all the plugs first.
use a screwdriver, etc. in the water pump pully bolts and put tension on the fan belt.
Should be able to turn the motor.