Merc 9.8 "clutch slipping"

[birgle]

Hello.

I have a 15 year old Mercury 9.8 2stroke that is displaying some funky problem. In layman's terms, it feels like the clutch is slipping.

The motor runs fine at idle and at idle speed when it is in gear. I can turn the throttle to about 15% and it runs just fine. Once I turn the throttle past 15% the motor cranks up but the prop does not spin any faster. This is a transmission issue of course but where would it be, in the lower area or upper? Is it something joe six pack can fix or do I take it to the motor man?

Thanks!

 

[Tyty]

Re: Merc 9.8 "clutch slipping"

Im not sure where your problem is but my personal opinion is I would have a mechanic fix it lower units are not easy to work on and if your going to tear it apart you may need some special tools which could get pretty expensive!

 

[ufm82]

Re: Merc 9.8 "clutch slipping"

The lower unit has no "clutch" so to speak. It runs gear-to-gear and there isn't anything that can slip in the LU. If you have LU issues, it may jump out of gear or be hard to shift. While I am often suspicious of the claim of "spun hubs" your issue sounds like that. Assuming you have a rubber-hubbed prop, dry the thing completely and mark the prop and the hub with a marker or white touch-up paint and test it on the water. If it "slips" pull the boat out and look to see if the marks are still lined up. If not, the hub is slipping and that is your answer. Rehubbing or even a new prop will fix it. (A new prop for a 9.9 can't be more than $100)

UFM82

 

[MandJ]

Re: Merc 9.8 "clutch slipping"

Hi all. I really hope Birgle found an answer to this problem. I'm having the same problem. anyone have any other guesses on a solution? To add a little information, if the motor is in forward gear the prop will make a ratchet sound when turned clockwise. Thanks everyone!

 

[bob1340]

Re: Merc 9.8 "clutch slipping"

H Once I turn the throttle past 15% the motor cranks up but the prop does not spin any faster. Is it something joe six pack can fix or do I take it to the motor man?

Thanks!

That's because the prop is not turning. The prop has a rubber hub that is slipping. These motors do not use shear pins in the prop. The slippage is a protective thing in the event the prop hits something. In your case it is probably just old. Joe six pac can fix it if he has a lot of stuff in his garage, but most just either send the prop in to be re-bushed or get a new prop.

 

[bob1340]

Re: Merc 9.8 "clutch slipping"

To add a little information, if the motor is in forward gear the prop will make a ratchet sound when turned clockwise. Thanks everyone!

That is normal and it's supposed to do that in forward. You probably need a new prop hub.