Outdrive "slipping"

grouch0jr

Mercury engines with bravo 3 drives.

While taking her out yesterday we got up on plane, then almost immediately the starboard engine RPMs increased and we fell off plane. We made sure the drives were all the way down and tried a couple more times. We couldn't get up on plane and stdb RPMs would shoot up, felt like it was "slipping" under load. We were able to limp back to the dock, and we were able to use the both engines to maneuver while docking, although it didn't quite feel right.

Once tied up at the dock we put the drives in the trailer position and did the "reach around" to check the props. They were both in place and didn't seem fouled. I check the gear lube reservoir and the level/color was not abnormal. I don't think its an outdrive probelm, it was a brand new SEI installed at the beginning of last season. I've read some threads that indicate it might be a failing coupler. I didn't smell any burnt rubber down in the hatch. Is there any way to check the coupler while it is installed? I saw that engine alignment can cause this problem, but I've never checked the alignment.

Also, any other ideas?

I figure I need to get the boat pulled... First thing I'll check will be to drain the gear oil and see if its full of glitter. 

rasbury

Sure sounds like the coupler to me- but I would not think there is anything in-between I lost mine on the water...was coming off plane and going slow- but there was no slip, burnt smell of rubber etc....I know you did not experience the latter. Unless something in the clutch /gears let lose. Its a pretty simple set up...
 

grouch0jr

I saw some other threads mentioning the cone clutch. Is there a way to narrow that down?

earl1z19

grouch0jr said:

I saw some other threads mentioning the cone clutch. Is there a way to narrow that down?

The only real way to sort out the cone clutch is to take the drive apart. A bad cone clutch will also exhibit a delay when engaging, once the engage they typically don't slip after.

Dream_Inn

I agree with the coupler as well.  So, when you say you've never had engine alignment checked, how long has that been?  Not that it is your issue, but I have my boat pulled every single March to have alignment checked (and anything else in the drive area if it needs it coupler, gimbal bearing... like this year was a new gimbal bearing).  Now, my boat is a bit heavier and harder on the drives.   You also should be greasing the coupler once a year.

grouch0jr

I just got the boat last season, so I'm not sure how long it has been. I also did not know to grease the coupler.

aero3113

Any chance you hit anything while getting up on plane? The coupler is the fail safe between the drive and the engine.

Dream_Inn

If your props had hubs, like mine, I’d say it sounds like that.  But B3 props don’t 

grouch0jr

aero3113 said:

Any chance you hit anything while getting up on plane? The coupler is the fail safe between the drive and the engine.

Its POSSIBLE I hit something, but we didn't feel or hear anything. I also have been thinking that maybe something was fouling the props, but maybe it cleared itself while we were docking (shifting between fwd and reverse).

I just got back from the boat. I took a look at the couple and didn't see any signs of debris or rubber dust. I also fired up the motor and shifted into fwd/reverse several times with a friend listening for sounds from the drive. I was getting thrust in both directions and there weren't any sounds.

After all that I noticed by trim reservoir was almost empty, so I topped it off and then noticed an oil slick out the back of the boat. I think once of the hydraulic ones to the trim ram may have ruptured? I don't think this could cause the other problem, but may have the same cause....