Merc 850 shifting

[jim46]

Dropped the LU and replaced the water pump now the engine pops out of gear in reverse when revs increase. Before dropping lower unit all was fine.
I have dropped the LU five times now trying to adjust the shifting. After the last time shifter started binding when in gear. I have followed the repair manual steps for installing the water pump and thats fine, could the shifter just go bad like this? I have tried makeing this happen out of the water by manually putting a load on the prop in reverse with no luck.

 

[Fuzzytbay]

Re: Merc 850 shifting

Have you adjusted the cable linkage? It may be related to that component, not just the lower end shift rod.

 

[jim46]

Re: Merc 850 shifting

Yes I have adjusted and readjusted the cable linkage. I disconnected the cable and found it bound up in the shifter mechanism. I was able to shift the unit by hand but it still didn't clear my problem of shifting out of reverse..

 

[corm]

Re: Merc 850 shifting

Hi,

Your reverse lock mechanism could be binding up.

 

[Chris1956]

Re: Merc 850 shifting

Jim, Does the gearcase shift into neutral and stay there? If so, disconnect the shift cable, and set the control to neutral and then adjust the barrel nut to fit the clamp. That is the proper way to adjust the cable. If it still doesn't work, you likely have problems in the control box or the gearcase.

 

[jim46]

Re: Merc 850 shifting

Tried that and I lose forward gear.

 

[Ken G]

Re: Merc 850 shifting

If it shifted before you took it apart the first time the problem is not in the shift cable adjustment. I'd guess you have the shift rod and/or the reverse lock cam out of position.

I would disconnect the shift cable. Drop the lower unit again. Shift the top half into forward using the lever at the power head. Shift the lower unit into forward using the shift shaft and verify that the prop will ratchet clockwise but not turn counterclockwise.

While in forward you have to visualize where the reverse lock rod rides on the reverse lock cam. In forward the rod meets at the low point on the cam. As the shift rod turns from F>N>R the cam pushes the rod up which in turn makes the reverse lock hooks drop down to engage the tilt pin. The shift shaft only turns about 30 degrees either direction from neutral so if the shaft or the lock cam is misaligned by a tooth either way the lower unit may not shift or will bind up.

Reinstall the L/U. If it is now shifting correctly then reinstall and adjust your cable.

I'm sorry if this sounds as clear as mud but its been 3 or 4 years since I've dropped a L/U on any of my Mercs. (I moved on to other projects). I had to figure all this out a few years ago when I replaced a worn reverse lock cam and did not make a note of the position of the old cam. Oops.

 

[jim46]

Re: Merc 850 shifting

I have done this and found that in forward and neutral I have a definitive lock of the shift cam in the lower unit but in reverse it pops out wirh the slightest pressure. I 'm takeing the lower unit to a shop. Thank you everyone for your input.
Jim

 

[jim46]

Re: Merc 850 shifting

Replaced the LU and found in the old unit rounded gear dogs on the shifter and reverse gear. All is well. Now all I have to do is adjust the throttle for top end speed.
jim