Yamaha F115 Need help with installing gear case

[Yamaha88]

I helped a friend install a water pump kit on his 2002 Yamaha F115 . Prior to removal of the lower unit, the remote control lever was verified it was in neutral position and the propeller spun left to right.

I removed the lower unit which released with no issue. After installing the water pump kit, the shift shaft, drive shaft and water pump grommet water tube was lightly greased. During the re-installation of the lower unit, I guided the drive shaft up the mid section and aligned the shift shaft and water pump grommet correctly. All the components slid in place smoothly but the gear case stopped about one inch short from fully mating to the bottom of the mid section.

Can't figure out what's preventing the lower unit from fully inserting back in place. As a test, I was able to insert the drive shaft all the way up if I didn't align the shift shaft into the housing. This tells me that the drive shaft spline is aligned and there is no blockage above..

In the Clymer manual, it advises to install a shift handle to realign the shift shaft position to N, F or R. I did not move the shift shaft since I know the remote control lever was in neutral and the prop spun left to right prior to removal of the lower unit.

The water pump grommet is in good condition and the water tube is clean with no blockage.

Clymer's manual also suggested to have another person "toggle the remote control lever to align the shift shaft splines" We tried that and it didn't work.

I've replaced water pumps on Suzuki, Mercury, Evinrude ,Johnson and 2 stroke Yamaha and never encountered this issue in the past 15 years.

Any suggestions would be greatly appreciated.

[TownsendsFJR1300]

Turn the main, drive shaft slightly. Don't mess with the shifter @ the helm..

Also, ANY excess grease ATOP the drive shaft (going into the crank) can stop any further movement (hydraulic lock)..

[Yamaha88]

I've tried turning the drive shaft clockwise and that didn't work. I inspected the crankshaft splines using a flashlight and didn't look like any excessive amount of grease that would create hydraulic lock.

One thing I did notice was black grease was slowly dripping down from the crankcase spline area. Temp was in the mid 90 degrees so maybe the ambient heat caused that issue which is probably something irrelevant to my current issue.

I just found info to turn the flywheel for alignment of the drive shaft but haven't tried that yet. Is this any different than turning the drive shaft by hand?

[99yam40]

I believe some F motors the drive shaft fits thru the oil pump.

you should be able to turn the prop shaft if the lower unit is in neutral and it is easy to tell if controls are in neutral

I am not sure what you were trying to tell us when you said " and the propeller spun left to right."

[pstephens46]

The last time I installed my lower I had to turn the driveshaft several times to get it aligned correctly. Keep trying.

[TownsendsFJR1300]

Forgot about the oil pump as 99Yam noted.

But yes, you can turn the flywheel a tad, keeping pressure upwards on the LU.

That's probably your issue...

[Yamaha88]

I believe some F motors the drive shaft fits thru the oil pump.

you should be able to turn the prop shaft if the lower unit is in neutral and it is easy to tell if controls are in neutral

I am not sure what you were trying to tell us when you said " and the propeller spun left to right."

"and the propeller spun left to right"

What I meant by that is when the drive shaft was not touching the crankshaft threads, the propeller can spin freely (by hand) in either direction with no unusual noise. So that confirms the gears in the lower unit is in neutral. Is that correct?

When the drive shaft is partially inserted into the crankshaft threads, the propeller can not spin in either direction. Is this normal? I've never had the need to mess with the driveshaft in any of my previous LU installs after a water pump service.

Appreciate all the replies....

[99yam40]

"and the propeller spun left to right"

What I meant by that is when the drive shaft was not touching the crankshaft threads, the propeller can spin freely (by hand) in either direction with no unusual noise. So that confirms the gears in the lower unit is in neutral. Is that correct?

When the drive shaft is partially inserted into the crankshaft threads, the propeller can not spin in either direction. Is this normal? I've never had the need to mess with the driveshaft in any of my previous LU installs after a water pump service.

Appreciate all the replies....

when the drive shaft is in the splines of the crankshaft, the drive shaft can not turn unless the crankshaft turns.
so if the prop shaft cannot be turned while the drive shaft is held from turning, then the lower unit is in gear

[Yamaha88]

Problem solved!


Had a assistant at the helm toggle the shifter while I installed the gear case. Shift shaft splines lined up (while toggling the remote shifter) and the gear case finally was able to slide all the way up. Tightened all the bolts and hand spun the prop. Prop would not spin and while remote shifter was in neutral. Lowered the gear case and turned the shift shaft to test forward, neutral and reverse position. I can hear a faint click when it falls into the next gear. Put shift shaft in neutral position since remote shifter was already in neutral. .

Repeated the process on toggling the remote shifter and gear case slid right up and bolted unit back together. Hand spun the prop in neutral gear, prop spun freely in both directions. In forward and reverse gear, prop would not spin which is normal.

Hope my experience can help someone else that runs into this same problem.


Thank you to all for sharing your knowledge.