Yamaha F75 lower unit removal...please help.

[nieking]

I have a 2005 Yam F75, and I can't get the lower unit removed for a water pump service. I have all bolts out including the one under the anode (5 total), but it won't drop more than an inch. Do I need to disconnect the shift selector shaft? If so, how? I am afraid to force the lower unit down as I could damage something. For the life of me I cannot find what it is hanging up on.

Thank you for any help here.

 

[robert graham]

Re: Yamaha F75 lower unit removal...please help.

Well if it dropped an inch, then that would seem to eliminate the drive shaft splines or shifter shaft splines as the problem. Have you cut or disconnected the rubber speedometer tube, as required? Maybe gently drive some wooden wedge blocks between the crack in 4 or 5 places and leave it overnight, but you better fix it so the lower unit doesn't get damaged if it just drops down in the middle of the night. Good luck and let us know what happens!

 

[nieking]

Re: Yamaha F75 lower unit removal...please help.

Yes, I have disconnected the speedometer tube. I believe that the shift selector is toothed and should slip in and out, but I'm not sure if it is from the top (under the power head-front), or at the lower unit where it separates.

The separation I am able to achieve is more like 3/4", but then it hangs. I can see the long vertical shaft for the shifter select move up and down as I push pull within the 3/4" range of motion while attempting to remove the lower unit. This lower unit has never been pulled for servicing as I'm just over 200 Hrs now, so I'm wondering if it is just a bit crusty and needs to be forced a little. I'll try the wood wedges, but I am still hesitant as I really want to be sure that there is nothing to disconnect from the shifter linkage (above or below).

I have the PDF F75/F80 manual, but it does not detail the steps for lower unit separation.

 

[robert graham]

Re: Yamaha F75 lower unit removal...please help.

On my 90HP the shifter shaft is a stainless steel splined shaft that sticks up from the lower unit about 2" and the upper part of the shifter shaft is splined and just slips down on it. If it's clean and some grease it should slip right off. Pretty much the same thing on the upper end of the drive shaft. I've heard that if the upper drive shaft splines were over-greased they can cause a suction-lock when trying to drop it down. Maybe the wooden wedges tapped in there lightly and left overnight? What you don't want to do is pull the shifter shaft up and out of the lower unit which would require disassembly of lower unit to fix. Good Luck!

 

[99yam40]

Re: Yamaha F75 lower unit removal...please help.

The parts break down show the shaft is splined, so it should just drop down. http://www.boats.net/parts/search/Yamaha/Outboard/2005/F75TLRD/LOWER CASING DRIVE 1/parts.html

But if it is pulling on the shift shaft instead of coming loose it maybe stuck so be careful. May try tapping on the shaft if you can get to it

 

[nieking]

Re: Yamaha F75 lower unit removal...please help.

Excellent diagram, thank you.

I can see that the toothed shift cam shaft should slip away from, or out-of the central body of the drivetrain (at part #34). It must be stuck/sticking, so I will be careful when I attempt to pull/pry it off again...likely this weekend.

Or it could be stuck at the tip of the drive shaft as Robert pointed out.

 

[robert graham]

Re: Yamaha F75 lower unit removal...please help.

Try the overnight wooden wedge tapped in there lightly, I've heard that steady, even pressure can work good sometimes....worth a try!...

 

[nieking]

Re: Yamaha F75 lower unit removal...please help.

I finally got around to trying to drop the lower unit again....today. I let it sit in the down position with one bolt in just a few threads to prevent the LU from falling off. Within an hour I noticed that it was resting on the bolt.

Water pump replaced. Thank you for the advice and Merry Christmas!

 

[robert graham]

Re: Yamaha F75 lower unit removal...please help.

That great!, and glad you got it off. You hear stories about nightmare situations where the drive shaft splines are corroded and stuck bad creating all kinds of problems. I guess if a motor is used regularly in salt water then probably a good idea to drop the lower end yearly just to inspect, clean and grease all splines, as well as replace the water pump impeller. They recommend waterproof marine spline grease in those areas. Good Luck!

 

[nieking]

Re: Yamaha F75 lower unit removal...please help.

All, I wanted to add a little more detail to this thread for the process I went through to replace the water pump impeller on my 2005 F75, as it could be helpful to others out there.

The reason that the lower unit was sticking, or not dropping as it should have was due to the drive shaft bushing being frozen/stuck to the drive shaft. The bushing is supposed to act as a guide/vibration dampener for the drive shaft, and the drive shaft should spin freely within the bushing as it stays stationary. Because it had seized to the drive shaft, it separated from the rubber outer shell that houses it. The rubber had disintegrated and came out in pieces once the lower unit dropped. The replacement bushing part for my F75 is (67F-45318-00-00). I had to break the old bushing off the drive shaft with a small hammer (carefully) and use emery cloth to polish the drive shaft imperfections. Pushing the new bushing in place was done with the outboard down/vertical and the use of a small floor jack and wood 2x2 with the corners rounded off to match the bushing dimensions. I used marine grease on the shaft and bushing to help prevent future issues.

The next challenge was removing the woodruff key that guides the impeller on the drive shaft. It is the half circle key that is pressed into the driveshaft. It was a real SOB to get out. Ultimately I had to use a small propane torch to heat it up, then cool it with an ice cube a couple of times. I also shot penetrant into the channel throughout the process. It seemed that the heating the shaft caused the penetrant to get sucked into the minute voids around the key and after cooling the key with ice I was able to tap the top edge of the key towards the shaft (not down) and cause the woodruff key to rock partially out of its groove. Vice grips did the rest. As Graham stated above, an annual inspection, cleaning and greasing of the shaft/splines is a good idea.