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Loss of Drive

R

ratmower

Advanced Contributor
"Hi
I have a Mercruiser alpha

"Hi
I have a Mercruiser alpha1 leg that looses drive once the engine rev,s have exceeded about 2,000 rpm.
The leg seems to select forward or reverse gear with no problems but as soon as you get above the 2000 rpm mark the engine will continue to rev freely but the leg looses all drive.
As soon as you back off the throttle below 2,000rpm the leg drives just fine.
Selector cable adjustments are OK so do you have any ideas what I may be looking at.
Any help would be greatly appreciated.
Regards
Peter"
 
"The prop hub is shot. The pro

"The prop hub is shot. The prop hubs are made out of hard rubber or plastic, sometimes brass. They are the sacrificail link between the prop and the drive. The idea is if you hit something this will save your gears. Many who have had groundings or hit partially submerged objects have experienced otherwise.
But they do wear out and start to slip."
 
"Great.
Thanks for the info,

"Great.
Thanks for the info, I will remove the prop and check it out but is there an easy way to discount or confirm the coupler if the prop looks OK, or are they my only 2 options for the described problem.
Regards
Peter"
 
"I would think that if the cou

"I would think that if the coupling was the problem, you would have some other indications, like noise and vibration, even when then engine was just idling.
When you pull the prop off, it may not be immediately apparant that the hub is spinning inside the prop. Remember, it only happens under some fairly heavy load.
My best advice is to replace the hub first. It's an easy job and relatively inexpensive."
 
"You can test to see if the hu

"You can test to see if the hub has spun by marking both sides and going for a spin. If the two marks are no longer aligned, the hub is shot.

Jeff

PS: Common problem."
 
"Thanks Jeff
The boat lives i

"Thanks Jeff
The boat lives in the water on a mooring so it is hard to mark the prop, although I may be able to use a centre punch and a hammer while having a swim.
Everything I have heard so far makes me fairly confident it will be the prop.
From memory the hubs are brass on the props, can the props be repaired if it is the hub or are they a throw away item.
Regards
Peter"
 
"The prop can be repaired--com

"The prop can be repaired--common practice--and you can remove the prop to mark it. It's easier that way.

Jeff

PS: With the prop off, you'll pobably see evidence that the hub is shot."
 
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