Help with Lower Unit

[Starplex]

I decided to change the water pump on the boat I just inherited, Yamaha 40 C40TLW. All went well, but I guess when greasing the shifter splines I must have moved the gear out of neutral w/o knowing it. Re-installed, cranked up on hose and noticed prop spinning very fast in neutral. Tried forward & reverse and no change. Dropped lower unit again, all works correctly from shifter to spine drive with lower unit off. With unit on the table I can feel the cam shifter as I rotate the shift rod, having resistance like it is moving the plunger correctly. However, the clutch dog seems to be jammed into the forward gear and is not releasing. Is there anything I should try before pulling the gear set? Thanks for the help.

[FabricGATOR]

Bench test

I don,t want to be master of the obvious, but you should be able to test the thing right on the bench, laying on the lawn, or hung on huge boat.

Simply put the engine into neutral (not running) and hand turn the prop. Engage forward and see if the prop locks to the drivetrain. Back to neutral and the prop should move freely by hand ( or foot if it is hanging on a transom) Again move shifter to reverse and and the prop should lock back onto the drive train.

Sometimes viscous friction, contact friction, can make it appear that the engine is in gear when running on the garden hose muffs.

Short of it is, if it worked fine before, and you just dropped the lower unit... Then if it's not right, your probably right about something not going back together correctly. Always go to where the last guy messed with it. It worked just fine when it left the factory.

[Starplex]

Thanks for the quick response. So I have tested with both the motor running and not running with the lower unit on. Gear is engaged in forward in all shift lever locations, (forward, neutral, reverse). A little embarrassment, I actually put in the river at the boat launch and when starting the engine, the boat launched forward into the boat dock. Shifting into reverse only made it worse. Removed lower unit & attempting to change the gear position by hand (turning the shift rod). No luck in getting the clutch dog to release from the forward gear. Have rotated the propeller shaft & the drive shaft independently while turning the shift rod. Still no luck. Suggestions? Thanks

[FabricGATOR]

Huh, did you run the engine before you did the water pump? There should be nothing except possibly missing the shift rod alignment. I'm not master mechanic like some of the posters here, but it wouldn't surprise me it Yamaha even had the shift rod splined so that you can't put it together wrong. (Cut the spline so it really only went together correctly)

I'd bet a dollar on a donut that you missed the shift rod completely and although it appears that you gears are welded together, your stuck in forward and moving the shift rod atop does nothing to the lower.

Do you get a solid clunking in the lower of the gears moving or just a mild click detention..... Like something is not quite connected?
Picture the spline of the rod laying up next to the other side of the rod it is supposed to be connected to. You might feel the teeth of the spline slightly mistaking them for the detent.

Irregardless, the lower must come off, so drop it and the manually move the shift rod on the lower while hand turning the prop.

[Starplex]

The lower unit is removed (on the table stand), and I've tried turning the shifting rod by hand while turning the shaft. No luck getting out of forward gear. I'm positive the shifting spline was engaged when previously installing the lower unit. I could visually see the line up prior to lifting the unit all the way up. Can't get the clutch dog to move off forward gear.

[rodbolt17]

ok.
the shift cam can rotate about 360*.
what you have done is allow the cam to rotate so the shift plunger is no longer in the cam groove.
you will need to gently rotate the shaft unitil it pushes the plunger back to the N position.
the cam has a flat ground on it to aid in locking in N.
the clutch assy is SPRING loaded to shove the assy towards the fwd gear.
if the plunger is on the HEEL of the cam due to excessive rotation it locks in fwd.
the farther you move the cam towards REV the harder it is due to the clutch spring compresses.

its a simple rookie mistake that has bit experienced techs.
some merc gearcases are built the same way and can do the same thing.
would not be the first gearcase I ever saw torn down cause the tech did not understand how it shifted nor why.

in other words.
rotate the dang thang back to where its posed to be and go play.

its also why you DO NOT NEVA EVA shift a Yamaha unit to fwd gear for removal/installation.
that's strictly a merc thang.

[Starplex]

Thank You. I used channel locks & rotated the shifter rod around with rag and channel locks. I found neutral. Whoo Hoo!!! However when I rotate around toward reverse it engages into forward. Tried the other direction & also engages into forward. Maybe the unit needs to be installed prior to trying reverse? Obviously installing in the neutral position. Comments?

[99yam40]

ok.
the shift cam can rotate about 360*.
what you have done is allow the cam to rotate so the shift plunger is no longer in the cam groove.
you will need to gently rotate the shaft unitil it pushes the plunger back to the N position.
the cam has a flat ground on it to aid in locking in N.
the clutch assy is SPRING loaded to shove the assy towards the fwd gear.
if the plunger is on the HEEL of the cam due to excessive rotation it locks in fwd.
the farther you move the cam towards REV the harder it is due to the clutch spring compresses.

its a simple rookie mistake that has bit experienced techs.
some merc gearcases are built the same way and can do the same thing.
would not be the first gearcase I ever saw torn down cause the tech did not understand how it shifted nor why.

in other words.
rotate the dang thang back to where its posed to be and go play.

its also why you DO NOT NEVA EVA shift a Yamaha unit to fwd gear for removal/installation.
that's strictly a merc thang.

Learned something new today, good to know. Thanks for posting it Rod.
Hope this old brain can remember it if I ever run into this situation in the future.

I am not any help to the OP though, maybe you did not find the actual neutral spot yet. Just a guess

[rodbolt17]

it only takes about 1 spline of rotation to move from N to R.
2 splines and it spring loads back into fwd.

I have only done this about 30 years or so.

remember that cam is sloped with a step in the middle for N.

move it off the slope and the plunger spring shoves the clutch fwd.

if it was working before you dropped it and you did not manage to somehow remove the shift shaft from the lower, you simply need to rotate the shaft to correctly position N and reinstall.

[99yam40]

Thank You. I used channel locks & rotated the shifter rod around with rag and channel locks. I found neutral. Whoo Hoo!!! However when I rotate around toward reverse it engages into forward. Tried the other direction & also engages into forward. Maybe the unit needs to be installed prior to trying reverse? Obviously installing in the neutral position. Comments?

Sounds like you would be best to find neutral put lower back on and then try shifting so it will move it just how far it needs to go and hold it there

[Starplex]

Thanks Rodbolt17 &99yam40. It worked like a charm as you described & I marked the spline in neutral & you are correct. A little over one spine of movement puts it into gear. I think before I was getting confused by turning the prop shaft vs the drive shaft (in my last post). I did notice though once back on the motor when shifted into Fwd, it won't turn backwards (racheting), & when in Reverse it doesn't rachet forward. But Neutral is Free. I'll put it on the water hose later today and validate both gears. It rotating correctly on the bench, just no ratcheting. Maybe this unit doesn't Ratchet.

[rodbolt17]

ya think?
I may have actually seen it once.

[Starplex]

ya think?
I may have actually seen it once.

I'm sure you've seen it many more times than once . I wasn't doubting you, just totally agreeing with you, as your instructions were spot on. Thank you again for the help!! Your a lifesaver

[rodbolt17]

depends on which wife you ask.

most techs most backyardigans go overboard.

I simply pick up the pieces.

if this monkey cluster was hard or required brains, I would be in a soup kitchen.