Lower unit stuck

Halfhitch

GreatGrady Captain
Joined
Nov 11, 2017
Messages
1,412
Reaction score
457
Points
83
Location
Venice, Florida
Is there any way to get an air chisel with a hammer head on it and be able to introduce some vibration into the shaft, even if it is from the side?
 

SkunkBoat

Well-Known Member
Joined
Oct 12, 2017
Messages
4,508
Reaction score
1,614
Points
113
Location
Manasquan Inlet NJ
Website
www.youtube.com
Model
Express 265
I was out replacing water pumps in my 3 year old Suzukis. First one was a breeze.

Second one had me worried I'd be hanging it like yours. Shaft was stuck up top like yours. Had to wedge it with home made oak shims. Finally got it but it took a long time wedging and shaking. Definitely some dusty rust in the spline like it never realy got coated with grease. So all the shaking I think we cracked the plastic pump housing where the water tube connects. Got one on order. THIS IS WHY YOU CHANGE THEM EVERY 3 YEARS. absolutely nothing wrong with the impellors and cups. they would last 10 years...

IMG_2137.jpg IMG_2139.jpg IMG_2141.jpg
 

family affair

Well-Known Member
Joined
Jul 31, 2010
Messages
1,437
Reaction score
339
Points
83
Location
Ohio
Model
Islander
I've pulled some nasty fasteners apart in my time. I've often thought penetrating oils were a farce. They are good once you get the fastener moving, but I've never actually witnessed one unfreezing a part. I've always had better luck with impact methods - air hammers, impact tools, hammer and punch, or any way to induce vibration.
Here is my $0.02:
  • Take a low impact energy impact tool and thread the prop nut on the prop shaft. Possibly double nut on the shaft or whatever is necessary to avoid damaging the threads. Spin the shaft back and forth while it is in gear to induce vibration into the shaft while driving wedges in. Full disclosure, I have no idea if this will damage gears.
  • Stuck driveshafts are common for Suzukis. I've reade about guys running the engine with the lower unit bolts loose shifting forward and reverse to induce shock to the crusty driveshaft splines.
  • I wonder if you run the engine on muffs long enough to get the power head warm could help a little while trying either of the above options.
 

SkunkBoat

Well-Known Member
Joined
Oct 12, 2017
Messages
4,508
Reaction score
1,614
Points
113
Location
Manasquan Inlet NJ
Website
www.youtube.com
Model
Express 265
idk about that...the engine only moves one direction.

After it was off I ran a scope up there. Blob of grease on the outside of where the spline goes. Looks like they put a blob of grease on the end of the spline but didn't rub it in to fill them. Then the blob came of as it pushed into the hole up there. The other motor(sequential serial#) was fine. full of grease.
 
Last edited:

DennisG01

GreatGrady Captain
Joined
Sep 1, 2013
Messages
7,189
Reaction score
1,341
Points
113
Location
Allentown, PA & Friendship, ME
Model
Offshore
I was out replacing water pumps in my 3 year old Suzukis. First one was a breeze.

Second one had me worried I'd be hanging it like yours. Shaft was stuck up top like yours. Had to wedge it with home made oak shims. Finally got it but it took a long time wedging and shaking. Definitely some dusty rust in the spline like it never realy got coated with grease. So all the shaking I think we cracked the plastic pump housing where the water tube connects. Got one on order. THIS IS WHY YOU CHANGE THEM EVERY 3 YEARS. absolutely nothing wrong with the impellors and cups. they would last 10 years...
I'm glad you got yours apart! I doubt you caused the crack to the impeller housing. There's already some play between the tube and the hole... and all the wiggle wiggle wiggle you did up above wouldn't really translate to THAT extent down below. Moot point and just a guess, though :)
 

TLCObsession

Member
Joined
Aug 11, 2022
Messages
15
Reaction score
1
Points
3
Location
Bellingham, WA
Model
Adventure
How about some heat and then melt paraffin against the shaft - works in similar automotive applications.
 

Willy-C

Well-Known Member
Joined
Nov 5, 2012
Messages
189
Reaction score
66
Points
28
Age
68
Location
Hooksett, NH
Just a thought….I work on hydraulic pumps on equipment that have a splined shaft similar to your issue Dennis. When we have troubles getting splined shafts apart we always see that the splines set up an uneven wear pattern that actually locks onto the opposing female spline. What works for us is trying to introduce vibration from an air chisel (with blunt end) on the side and try to reverse the shaft rotation it normally turns to get it to back in line with the other splines. When we see orange rust coming out of the splines we know it is working.
 
  • Like
Reactions: Halfhitch

Willy-C

Well-Known Member
Joined
Nov 5, 2012
Messages
189
Reaction score
66
Points
28
Age
68
Location
Hooksett, NH
The example on the left is one that was worn enough to lock onto the female spline (you can see the teeth were not worn on the end). It seemed to be loose in the housing but a slide hammer never budged it.
The example on the right is a new replacement shaft.
So by reversing the torque with vibration hopefully it can break free. If not then it’s just plain ole fashioned rust….:mad:
 

Attachments

  • C737C15E-989F-4E05-8691-D8C33F1EB318.jpeg
    C737C15E-989F-4E05-8691-D8C33F1EB318.jpeg
    720.5 KB · Views: 22

hooked on Grady

Well-Known Member
Joined
Nov 18, 2019
Messages
190
Reaction score
142
Points
43
Location
northern New Jersey
Model
Offshore
I like the opening, where someone is banging on the LU with a steel claw hammer. But my favorite part, around 9:20, after the thing is completely trashed, is when he says, "........AFTER getting really aggressive with it, and the LU still isn't coming off, THEN it's time to figure out what kind of model engine you have, and how it is put together."
yup, Now is definitely the time.
 

DennisG01

GreatGrady Captain
Joined
Sep 1, 2013
Messages
7,189
Reaction score
1,341
Points
113
Location
Allentown, PA & Friendship, ME
Model
Offshore
Did you ever get the lower unit off?
Well this is really strange. I could have sworn I updated this thread... but apparently not!

In a nut shell... nope. I tried everything - all kinds of fluids, air chisel on the end of the crank, wedges, etc, etc. It ended up being hung upside down for a couple months.

Somewhere along the way, a comment was made that because the crank is steel that there's a possibility that the two pieces are "welded" together from the rust and separating them "could" mean that the splines end up being disintegrated/destroyed in the process.

I put it all back together and will run it till the impeller starts to go bad - in the mean time, if I find a good deal on a newer, used 250HP I'll probably get it. I'd likely be looking for an F250 in the sub $10K range.
 

DennisG01

GreatGrady Captain
Joined
Sep 1, 2013
Messages
7,189
Reaction score
1,341
Points
113
Location
Allentown, PA & Friendship, ME
Model
Offshore
UPDATE:

As a last ditch effort, I was at a local Yamaha shop for something else and got talking with their lead tech about my lower unit. I explained everything I did but he said he felt confident that he could get it apart. I figured, what the heck - give it a shot! A week later he called me and said "OK, I see what you were talking about, now!" He said he never came across one this hard. But we agreed to go ahead and keep going - he called a day later and said he had it about 1" apart - which is more than I ever got.

He said the upper splines of the driveshaft/crank seemed solid - which, in my mind, made continuing with this effort worthwhile. With that in mind, I said go ahead and keep going. I also dropped off my spare lower unit and our thought was that if it didn't all of sudden start to come off, then go ahead and destroy the existing lower and put a slide hammer on the remaining driveshaft stub. That's what he did. The spare lower is rebuilt and on the engine and he said the test ride went well... other than dropping RPM at high RPM's... but I already knew that ;)

Anyways, just wanted to follow up that it's off. Although considering most people don't have a spare lower unit laying around, it's probably not a technique that most would use to get it off! :)
 
  • Like
Reactions: PointedRose

Halfhitch

GreatGrady Captain
Joined
Nov 11, 2017
Messages
1,412
Reaction score
457
Points
83
Location
Venice, Florida
Thats good news Dennis. Just what did that mechanic do that you hadn't done that made it move?