Mercruiser 898 lower unit shifting problems

[thormx11]

I recently changed the impeller in my mercruiser 898. It shifted/sounded fine before I touched anything. Now the lower unit doesnt want to stay in a gear. When I turn the shift rod by hand (with the lower unit off) It will lock into a gear (I can tell by which way the prop wont/will spin) but after the prop spins any It goes right back into nuetral (spins freely either direction)

Any idea what would cause this?

 

[Bt Doctur]

Re: Mercruiser 898 lower unit shifting problems

thats is correct.when in fwd, the prop shaft is locked CCW but if you turn the prop shaft CW you will see the splined shaft move CCW a bit. this is because the shift dogs are "unwinding" so to speak because of the way they were cut.same thing for reverse.that is why some say to hold the prop tension CCW with a bungee when installing a lower unit.

 

[thormx11]

Re: Mercruiser 898 lower unit shifting problems

So this is not a problem?

Another thing, when I put the lower unit back on the first time, it would shift fine but would make a grinding sound when shifting, I know it is supposed to make a little sound when shifting, but this sound goes on almost until you put it into full throttle, then it quietens up. Sounds like its not shifting quick enough through the gears.

 

[Bt Doctur]

Re: Mercruiser 898 lower unit shifting problems

you do need to shift smartly and not baby the process,sometimes a slight readjusting is necessary.

 

[thormx11]

Re: Mercruiser 898 lower unit shifting problems

I am about to replace the lower unit and see if it is fixed or not. hope so!

 

[thormx11]

Re: Mercruiser 898 lower unit shifting problems

I put the lower unit back on (making sure to keep in in the right gear) and it shifts fine, but when you have it in reverse it seems to make a grinding sound. it sounds fine in forward gear.

 

[Bt Doctur]

Re: Mercruiser 898 lower unit shifting problems

try pulling the cotter pin at the brass barrel and turn the barrel a few turns clockwise to see if it improves.
maybe your total throw needs a bit of adjustment. all that is described in the merc manual.post 9 here
http://forums.iboats.com/showthread.php?t=563399

 

[thormx11]

Re: Mercruiser 898 lower unit shifting problems

I have not tried adjusting the barrel at all yet, but today while fiddling with the boat, I noticed the grinding noise from the lower unit seems to be the OD slipping out of gear. I noticed when I put it in reverse and rev it up a little, the prop grinds and then it will slow down (like its put into neutral) then grinds again and speeds back up (like it goes back into reverse). It will make these changes every few seconds. Fwd gear doesnt seem to do it nearly as badly as reverse.