Lower unit stuck

[DennisG01]

When I bought this Grady (about 6 or 7 years ago), I did not immediately drop the lower unit from the Yamaha OX66 250HP. Well, two years later I tried... no luck. Tried again the following year, no luck. I tried everything... wedges, hammer, a bigger hammer, leaving the securing bolts loose while running the boat... nothing. I can get some space between the lower and the mid-section at the back or front of the lower unit (not at the same time), but not really anything in the middle. This leads me to believe that the driveshaft is stuck in the crank. Not an unheard of problem.

Currently, it's still pumping really good water (I generally boat in deep water) but I want to give this another shot this winter BEFORE I "need" to do it. So I brought the boat home from Maine (I'm in PA) this year. Here's my plan:

-- Hang the engine upside down by the lower unit and loosen (but not remove) the main bolts that hold it together along the side of the casing (I'll fully remove the other ones)
-- Dribble all kinds of salt/rust eating liquid onto the driveshaft (which I think I can get to) over the winter. Phosphoric acid, muriatic acid, industrial vinegar (30%), whatever. Probably all of them!
-- Add some wedges for good measure
-- If I can get an air chisel (with a blunt tip) onto the driveshaft, gently use that to shock the driveshaft.

My last resort would be to cut a hole in the midcase and cut the driveshaft and then try using a slide hammer on the shaft stub. I do have a spare lower unit.

Questions for anyone with ideas:

-- How to freakin' hang it? The only thing I can think of is to use a ratchet strap (two, just for caution) between the anti-vent plate and gear housing with a rope tied onto the strap on either side of the lower unit, making a "loop" that I can then hang the engine by. I don't think the strap will slide off.

-- Any other ideas/words of wisdom?

 

[Hookup1]

Did you take the zinc off? The one behind and above the prop.

 

[SkunkBoat]

I'm no motorhead so forgive me if I'm way off but..
Is it possible to spray some Liquid wrench/WD40 from the lowest intake and reach the bottom of the crank?

 

[seasick]

This probably isn't going to help but watch it anyway. The last section is the worst case scenario

yamaha lower unit stuck video - Yahoo Video Search Results

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[Halfhitch]

If your old OX66 still runs good and is still peeing good. I would grease up the bolts, tighten them back up and run it till something actually breaks. Those are really tough engines they say, so to purposefully do things to it that are going to require who knows how much money and time to make right, doesn't make sense to me. The motor doesn't have a lot of value to a stranger on the open market, but to you, who has faith in its dependability, it has a lot of value. Use it.

 

[glacierbaze]

Did you take the zinc off? The one behind and above the prop.

3 bolts there. 12mm under the plastic cap holds the zinc from the top, and two 14mm from the bottom after the zinc is out.

 

[SkunkBoat]

This probably isn't going to help but watch it anyway. The last section is the worst case scenario

yamaha lower unit stuck video - Yahoo Video Search Results

The search engine that helps you find exactly what you're looking for. Find the most relevant information, video, images, and answers from all across the Web.

video.search.yahoo.com

2 man job! when he pulls the LU and leaves it dangling on a bent shaft....not good

 

[Halfhitch]

2 man job! when he pulls the LU and leaves it dangling on a bent shaft....not good

I agree, that video reminded me why I don't like those marina hacks working on my boat unless I'm there to stop some of their bullshit. Like driving steel chisels between two aluminum components. Holy crap!

 

[glacierbaze]

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."

 

[DennisG01]

Thanks, guys. All good info.

-- Yes, all bolts were out
-- Yes, I did try squirting various chemicals up towards the crank, but unfortunately gravity was fighting me and not allowing the chemical to stay in contact with the shaft/crank connection. Hence my thinking that hanging it upside down may/hopefully help.
-- The issue I have with wanting to do it now is that I don't want to risk getting stuck in the middle of the season without a boat. I have others that I could use, but I'd rather attempt this on my own schedule.
-- Good video - that pretty much explains what I think I'm up against!

 

[PointedRose]

If you tilt the engine all the way, while parked on an incline, could there be enough slope to allow penetrating oil to work its way down the shaft? or can you build a bracket/mount to help you invert it while still attached with mounting bolts, rather than just hanging it

kroil penetrating oil is worth trying

 

[Halfhitch]

The predicament Dennis finds himself in should be a heads-up to us all that there is more than an impeller change as a reason to drop the lower unit periodically and to grease the hell out of the splines on re-installation.

 

[HMBJack]

That Lower Unit may not have been removed for ten years (long before you bought it). It might be welded in place by now.

You could destroy the engine trying to do what you want to do. I agree with the above recommendation to use it until something happens. Yamaha impellers are over built. I had one go nearly 1,000 hours and it still looked decent. Keep trying to remove it but I wouldn't try too too hard.

 

[DennisG01]

If you tilt the engine all the way, while parked on an incline, could there be enough slope to allow penetrating oil to work its way down the shaft? or can you build a bracket/mount to help you invert it while still attached with mounting bolts, rather than just hanging it

kroil penetrating oil is worth trying

I have the space and means to be able to hang it relatively easy -- other than the question above about HOW to attach straps to the lower unit -- so taking it off isn't a big deal. I want to bleed the steering lines, anyways to see if that fixes a somewhat stiff steering issue.

I've never used Kroil but have heard some good things about it. I don't know if it's really a "salt" eater? But hey, I'm always open for new tools - and that's kind of like a tool, right? I'll get some!

 

[DennisG01]

The predicament Dennis finds himself in should be a heads-up to us all that there is more than an impeller change as a reason to drop the lower unit periodically and to grease the hell out of the splines on re-installation.

Yup.

 

[DennisG01]

That Lower Unit may not have been removed for ten years (long before you bought it). It might be welded in place by now.

You could destroy the engine trying to do what you want to do. I agree with the above recommendation to use it until something happens. Yamaha impellers are over built. I had one go nearly 1,000 hours and it still looked decent. Keep trying to remove it but I wouldn't try too too hard.

That's interesting. I'll see how things go - maybe I'll stop short of any destructive measures...

 

[steveditt]

I know of the problem friend needed to cut the shaft , I agree if its still working continue using it until you have to address the issue , I saw youtube guy turned it over and with all lub and heat it did come apart . Before your impeller goes bad maybe something else will fail .

 

[seasick]

That youtube channel is actually pretty informative. If I hadn't watched it before I would also think he was a hack but having watched many of his videos I think that he knew right off the bat that the drive shaft was 'welded' to the power head. He knew it was basically a lost cause but went through all the steps, drastic and all that one might try to free the lower unit. I also wouldn't him for dangling the LU and potentially bending the input shaft. He knew the shaft would have to be cut to possible save the power head. In Dennis's case, since he has a spare LU, he may end up cutting the shaft also and may need to smash the casing to get access to cut it. Even then, he may not be able to get the shaft out of the power head.

 

[SkunkBoat]

Thanks, guys. All good info.


-- Yes, I did try squirting various chemicals up towards the crank, but unfortunately gravity was fighting me and not allowing the chemical to stay in contact with the shaft/crank connection. Hence my thinking that hanging it upside down may/hopefully help.

My point was to try spraying into the lowest air intake (reed valve) and that would flow DOWN to the bottom of the crank?

 

[DennisG01]

My point was to try spraying into the lowest air intake (reed valve) and that would flow DOWN to the bottom of the crank?

Hmmm. OK, I didn't pick up on that. So... thinking through this... I'm kinda "writing outloud" as I think... it might be pot luck to get a chemical past the piston rings and to the right spot... I'm trying to envision if a chemical (if the piston was stopped to expose the exhaust port) would even make it to the end of the crank? I mean, the crank lower end is exposed to the environment (hence the problem) whereas the exhaust takes a different path. And even so, the driveshaft is a male and the crank is a female so while some of the chemical may wick it's way in, I don't think it's going to make it there at all. Am I thinking through that correctly?