Engine Coupler Overheat ?

[tahoejag]

After reading several posts, what or why does the engine overheat when the coupler goes bad? Would not the spline/shaft just free spin?

 

[MWG2600]

Re: Engine Coupler Overheat ?

With an alpha 1 the raw water pump is in the lower unit. If the lower unit is not turning because of a bad coupler then neither is the water pump.

 

[Don S]

Re: Engine Coupler Overheat ?

There are basically 2 ways a coupler fails. If the splines separate from the rubber, at low rpm the drive may turn and you may actually be able to move along at idle. BUT as you give it rpm it slips more due to the load. This is when you smell burned rubber. It's acting just like a spun prop hub, only no water to keep it cool.
Basically, the raw water pump would work at low rpm.

The second way is if the splines are stripped out of the coupler. Then, there is nothing to turn the splined shaft going to the drive, and the pump doesn't work at all.

 

[tahoejag]

Re: Engine Coupler Overheat ?

Yes...that makes a lot of sense....water pump no turnee...no coolee!

 

[Don S]

Re: Engine Coupler Overheat ?

Yes...that makes a lot of sense....water pump no turnee...no coolee!

Could also be stripped gears in the upper gear, or a broken vertical shaft. Turn the engine over with the starter and see if the input shaft of the drive turns.

 

[tahoejag]

Re: Engine Coupler Overheat ?

Don S...its all good with my engine. I just read about it and was curious, if ever happened, would know what to look for. This forum is AWESOME to gain info, learn and feedback to others. I can tell there is a lot of knowledgable persons on here that been around boats (including yourself! ). GO TIGERS!!!!