How to diagnose a "spun coupler"?

[kilowatts]

Hi Guys:

I have a 1974 Mercruiser inline 6 mod 165 in a Grew 22.5 cuddy.

How can I tell whether or not I have a "spun coupler"? That is to say, how can I tell whether or not the coupler has deteriorated to such an extent that the power from the engine is not transmitted to the outdrive through the gears?

Please let me know what you think.

kilowatts

 

[achris]

A few symptoms will be immediately noticeable, depending on how deteriorated the coupler is.
1. No or limited drive when gears engaged. May act the same way as a spun prop hub.
2. Engine overheats (No drive to the water pump).
3. Possible smell of burnt rubber emanating from the back of the engine.

Chris.....

 

[Fun Times]

If your lake testing the boat and you have access to the rear of the engine, you could try marking the stern drive input shaft and the engine coupler then check to see if the alignment lines have moved away from each other or not after running. Same theory goes for the propeller hub.

Good luck.

 

[kilowatts]

Hi Guys:

Thanks for your responses.

No problem with the prop hub. Don't see or smell any burnt or broken rubber parts in the bilge under the coupler.

When I put it in gear and apply gas I get adequate revs but not enough power to get on plane! No sign of overheating, no unusual noises just no power! I can't think of anything else other than the coupler. The engine is in great shape as is the outdrive, regular maintenance and recently tuned.

Please let me know.

kilowatts

 

[alldodge]

Pull the drive and look at the drive shaft and splines. If all looks good pull the top cap off the drive and have a look. If the bearings start to melt you may or may not hear anything

Also pull the prop off and look at the rubber hub it the center

 

[thumpar]

What RPMs are you getting at WOT?