Johnson 9.9 prop slips

D

DouglasGSmith

Recruit
Joined
Jul 29, 2006
Messages
4
I've just bought a 1991 - 9.9 HP Johnson with very low hours. It runs fine at lower RPMs, but when I rev it up, it makes a great deal of noise but actually slows down.

It's acting as if there is a clutch and it's slipping. Is there a clutch and it that possible? Other thoughts?

BTW, when I got it out of the water their is a white grease in the prop hole.
 
O

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: Johnson 9.9 prop slips

Sounds like your prop hub is spun Douglas.You can make two reference marks on the hub and prop barrel and water test to confirm.Your dealer or a prop shop can get you fixed up.As for the white grease in the prop barrel,I suspect your lower unit carrier or propshaft seals may be leaking.Remove the drain plug from the lower unit and inspect for water intrusion.Milky or emulsified appearance will confirm.
 
D

DouglasGSmith

Recruit
Joined
Jul 29, 2006
Messages
4
Re: Johnson 9.9 prop slips

ob said:
Sounds like your prop hub is spun Douglas.You can make two reference marks on the hub and prop barrel and water test to confirm.Your dealer or a prop shop can get you fixed up.As for the white grease in the prop barrel,I suspect your lower unit carrier or propshaft seals may be leaking.Remove the drain plug from the lower unit and inspect for water intrusion.Milky or emulsified appearance will confirm.
Click to expand...
 
D

DouglasGSmith

Recruit
Joined
Jul 29, 2006
Messages
4
Re: Johnson 9.9 prop slips

Thanks for the reply. I'm not clear on the term "prob hub is spun". Can the prob hub separate from the prop itself, i.e. become two pieces? If so, could I tell that by just removing the prop and examining it?
 
O

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: Johnson 9.9 prop slips

Basically yes.The rubber hub portion becomes unbinded from its interference fit in the prop barrel and will spin freely when placed under enough load.Sometimes you can simulate this by hand and sometimes not.Close inspection of the fit and or using refernce marks and then placing back under load again is a sure way to detect if it can't be done by hand with the engine in gear and not running.This is a failsafe design of sorts that prevents catastrophic internal lower end damage if the rotating prop encounters an underwater obstruction/bottom.
 
You must log in or register to reply here.
Top