1988 90 HP intermittent reverse problem

[tsjustme]

I searched the forum for "reverse" related posts, but did not find one that addresses my problem. I have a 1988 Merc 90 HP, I3, Electric Start, long shaft, power trim, with oil injection. SN: 0B329506.

I just bought it this spring. Yesterday, I noticed for the first time a problem with reverse. At higher throttle in reverse, it seemed like it was slipping in and out of reverse. When I put it in neutral, there was a clicking sound like the prop was still turning and trying to disengage from reverse but couldn't. Shifting to forward and then back to neutral put it into neutral.

Any ideas? Could it be simply a control cable adjustment? The Clymer Mercury manual I have doesn't include cable adjustment procedures.

Thanks in advance for your help.

 

[Wingedwheel]

Re: 1988 90 HP intermittent reverse problem

It could be a few different things. When you put the shifter into neutral does it make a ratchet sound or a 'clunk'? Typically you don't want to ease it in as it wears the lugs on the clutch-dog. How does the lube in the LU look? when not running does the shifter seem to work well?. You may have to do a few troubleshooting steps before you can determine if you have a problem and what it is.

 

[tsjustme]

Re: 1988 90 HP intermittent reverse problem

Thanks for your quick response.

Starting just yesterday, while in reverse and at a slightly higher rpm for a faster reverse motion, the lower unit seemed to slip out of reverse and back into reverse with a clunk.

Shifting back into neutral, the lower unit had a racheting (clicking) sound.

Shifting into forward and then back to neutral cleared things up.

When not running, the shifter moves easily.

The LU oil is clean and full.

 

[tsjustme]

Re: 1988 90 HP intermittent reverse problem

For clarification, when I said "Shifting into forward and then back to neutral cleared things up," I meant that I have to do that each time I get the clicking sound when going from reverse to neutral. The entire problem isn't "cleared", just the last incident.

Thanks for your quick response.

Starting just yesterday, while in reverse and at a slightly higher rpm for a faster reverse motion, the lower unit seemed to slip out of reverse and back into reverse with a clunk.

Shifting back into neutral, the lower unit had a racheting (clicking) sound.

Shifting into forward and then back to neutral cleared things up.

When not running, the shifter moves easily.

The LU oil is clean and full.

 

[Wingedwheel]

Re: 1988 90 HP intermittent reverse problem

If its slipping out of Rev and ratchets when trying to shift into Rev it sounds like the cogs on your clutch-dog may be worn. The only way to check that is to go into the gearcase. Not a hard job if your mechanically inclined or your marine mech can take it apart in about an 1-1 1/2 hours at $95 an hour. In any case I doubt its an adjustment. Hope that helps.

 

[tsjustme]

Re: 1988 90 HP intermittent reverse problem

If its slipping out of Rev and ratchets when trying to shift into Rev it sounds like the cogs on your clutch-dog may be worn. The only way to check that is to go into the gearcase. Not a hard job if your mechanically inclined or your marine mech can take it apart in about an 1-1 1/2 hours at $95 an hour. In any case I doubt its an adjustment. Hope that helps.

I've looked at the parts diagram in my Clymer manual and I can't see any part called a "clutch-dog". The only "clutch" part shown is a "Clutch actuator rod" that goes between the "cam follower" and the propeller shaft.

Can you tell me what a "clutch-dog" is?

 

[Wingedwheel]

Re: 1988 90 HP intermittent reverse problem

you're right about the parts listing. Look at this diagram and its part# 47, identified as a 'ratchet.' That is what most people refer to as a clutch-dog. It engages your forward and Rev gears that are turning on your pinion with your driveshaft. If you look at the ends it has lobes to engage the gears. The reverse side is square and the FWD side has angled lobes. Thats what allows your prop to spin in one dirsection when in FWD. Tha rear gear lobes are square and lock the shaft in both directions. Typically if the square lobes are rounded off the 'clutch' will slip off under a load. Almost always its rev because the reverse direction is spring opposed while the fwd is spring assisted. My Clutch-dog runs about $360. Your doesn't look too bad as far as price. http://www.boats.net/parts/search/M...1999/Gear Housing(Propeller Shaft)/parts.html