Lower unit stuck

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?
 
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...

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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.
 
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.
 
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SkunkBoat said:
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...
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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 :)
 
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.
 
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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:
 

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glacierbaze said:
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."
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yup, Now is definitely the time.
 
Saltyone said:
Did you ever get the lower unit off?
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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.
 
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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! :)
 
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