Rotation of engine

[tejay129]

I bought a '91 mariner 275hp O/B. It has no prop. How can I tell if I need a RH or LH prop?
If the shifter in neutral, I can turn the prop shaft both directions. If it's in reverse I can move the prop shaft clockwise but not counter-clockwise and when it's in forward I can move the prop shaft counter-clockwise but not clockwise. All of this is looking at the motor from the back facing the transom. Thanks.

 

[SparkieBoat]

Re: Rotation of engine

most single engine applications will be RH...but you may have gotten a hold of a CR motor...you can crank your motor and bump it into gear and see which way the prop spins to make sure. sounds like a RH by the way you described how you tested it.

 

[tejay129]

Re: Rotation of engine

Thanks, it was part of a set at one time so I know one of them was CR. I assumed that when I couldn't move the prop shaft C/W with the shifter in FWD it was because your are not able to turn the engine over with just the prop shaft. A final note: What would happen if you ran a LH prop on a RH engine? Would it still go forward?

 

[bassman284]

Re: Rotation of engine

It would if you put it in reverse.

 

[Don S]

Re: Rotation of engine

A final note: What would happen if you ran a LH prop on a RH engine? Would it still go forward?

Do not change directions by replacing a prop. The gear setup and thrust is designed for a particular direction. You could just change the prop and it would work, but only for a short time until the lower destroyed itself.

 

[tejay129]

Re: Rotation of engine

Thanks, does anyone else agree that it's right hand rotation if the shifter is in fwd and the prop shaft will not turn c/w by hand with the engine off?

 

[Fed]

Re: Rotation of engine

Nope, you have a CR.

 

[SparkieBoat]

Re: Rotation of engine

crank it up and bump it into forward and see which way it spins

 

[tejay129]

Re: Rotation of engine

Thanks everybody. It is a CR.

 

[SparkieBoat]

Re: Rotation of engine

got to hate mercurys serial number system...for just these kind of reasons..most other makers would have a model number that specifies it is a CR...but I guess someone could always change the foot..I have seen that before.