Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S. :)

[rfdfirecaptain]

I think this may be a Don S. question:
See signature below for engine and outdrive setup: While traversing north on the Intracoastal Waterway I had been on and off the throttle when meeting about 15 boats that were headed south. After about 40 miles I slowed to a stop and the engine was idling while I waited for a bridge to open. When I eased the throttle forward for idle speed to pass under the bridge I had no forward propulsion and I heard a whining sound. Also, I had no reverse.


I haven?t pulled the outdrive off yet, but I have made three key observations. #1 the engine is running perfect. #2 When the gear shift level is engaged the props are freewheeling. #3 I don?t recall hitting anything and there is no obvious damage to the props or outdrive. It sounds to me like I have sheared a key somewhere on the drive shaft.


I have rebuilt this outdrive and installed a new engine over the last three years, but I can?t remember all the mechanical details. Based on my recollection I think there is a keyway on the engine drive shaft, inside the transmission, that attaches the transmission spline shaft to the engine drive shaft, by way of a ?double female? coupler. Problem is, I just cannot recall how these parts are put together and to make a visual observation I would have to pull the engine. Of course I?ll know more once I pull the outdrive. In the meantime any help pointing me in the direction of where to look and what to look for is appreciated. Hopefully I?ll get the outdrive off later this afternoon, get the boat started up and see if the transmission driveshaft is spinning. Sadly, I still have to clean the boat etc. before I can get started working on it.

 

[Don S]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

There is a coupler between the upper and lower, they used to be called drive savers. If it breaks nothing works. Might want to pull the upper gear box and look at it. no need to pull the whole drive.

 

[rfdfirecaptain]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

Thanks Don! I hope to have the outdrive off in a few hours to see if the transmission spline shaft is spinning. I'll update the thread asap when I get that far. Hey, any idea what could cause this to happen when I haven't hit any submerged objects? Especially considering the fact that it was working fine at crusing speeds of 25Mph - 30 Mph on minutes before it let loose.

Thanks!
Keith

 

[Don S]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

Hard to say "Why" something happened, when you don't know "What" happened.

Once you figure out what broke, then we can see if possible to figure out why it broke. Have you checked to make sure the shift cable actually works? Had a customer bring in his drive because it didn't work. Took it all apart, nothing wrong. He brought the boat in and found the cable end broke off at the helm control.

 

[rfdfirecaptain]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

Yes sir, the shifter cable is working fine. It appears to be throwing the eccentric piston fully into the forward and reverse positions leaving the props freewheeling. Not sure I am experienced enough to positively diagnosis this on my own without removing the outdrive to see if I can isolate the problem to something in the outdrive or the transmission. But, I'll give it a good look over first and give it my best effort.

 

[Don S]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

Without going to all the problem to pull the whole drive, just remove the upper gear box. (15 minute job)
From there you can see if the coupler between the upper and lower is broken.
If it's OK, turn the prop and make sure the vertical shaft is turning.
On the upper gear box, shift it into gear and turn the ujoint shaft in the direction of engine rotation and see if the vertical shaft catches or not. (shift both directions, and hold the shaft to see if things turn or not.
Look inside the bellows and have someone crank the engine over. Does the primary drive shaft in the flywheel cover turn?

After those tests, you should know something. All without pulling the drive.

 

[rfdfirecaptain]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

UPDATE: I loosesned the bellowes around the U-joint and engaged the props. When I spun the props there was no movement at the U-joint. So, I pulled the drain plug on the outdrive. It's covered with metal shavings. I'll dive in the upper housing next and see what I find there. Any ideas in consideration of this updated information?

Also, when I find the problem how do I ever get all the metal shavings flushed out of the outdrive?

 

[Don S]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

You have to completely disassemble the upper and lower and clean all the parts. Bearings are probably all junk if the oil was full of metal, could also have damaged the hard facing on the gears. Check them all carefully.

You mentioned you rebuilt the drive. Did you get everything shimmed properly, with proper gear contact patterns? I assume you had access to all the special tools. Rebuilding and re-shimming a DP is not an easy process to get right.

 

[rfdfirecaptain]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

OK Don… I found the problem. It’s the definitely the “spline coupler”. (see photo) Only the top half was stripped out and from the looks of my magnet I think I have captured 90% all the metal shavings. (see photo) Honestly I don’t want to tear the whole thing down if I don’t have to but I will if that is your final recommendation. I’m not trying to be cheap just practical based on the amount of metal shaved and metal captured. Isn’t there some way to force a cleaning solution through the whole outdrive… spin the props a few times and wash it out repeating the process over a couple of times? Maybe I could do it using a thinner oil like a hydraulic fluid? I realize that is not something a technician would do in a shop setting. So before you call me stupid and drop my problem like a bad habit just know I’m trying to be practical based on what I see.

I see no damage to the spline shafts and I truly doubt there is any other damage because it was a catastrophic failure when this thing let go. From that point the outdrive was never engaged for more than 5 seconds total on the three attempts I made to put it into gear.

OK I’ll take my leg streaking now

 

[rfdfirecaptain]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

Don, regarding your rebuild questions: I didn’t mean to imply I "rebuilt" the whole thing from scratch. I’ve rebuilt the lower pretty much from scratch cause I replaced the carrier bearing. The other work I did was replacing seals, orings and bearings in the upper housing.

No, I didn’t have any special tools and the shims that came out were the same ones I put back. Call me stupid, but it fit together nicely, it passed pressure tests and it seemed to run like a sewing machine.

I think the problem I have now is a result of a crabpot rope that became entangled in my props last season. Based on what my parts man says that is a common cause which often results in damage to the spline coupler.

 

[Don S]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

No, I didn’t have any special tools and the shims that came out were the same ones I put back. Call me stupid, but it fit together nicely, it passed pressure tests and it seemed to run like a sewing machine.

I've rebuilt a lot of those drives (It was my job) and changed bearings in a lot, and the shimming always changed. If you don't get the shimming and preloads right, they will run fine for a while. Right up 'till the day they come apart.

There is a reason for all those special tools and procedures.

 

[rfdfirecaptain]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

I totally get what you're saying Don, no doubt you are the Volvo expert. It sounds like (in this case) working on this particular outdrive at home is really not a good option unless it’s basic maintenance. From what you are saying it would take several mail orders at various benchmarks in the repair process just to get in hand all the "correct" parts, such as shims. At that rate a simple bearing or seal replacement could take 2 weeks to complete.

Thinking right now the one “Special Tool” I need to solve all my boat problems is a stick of dynamite! At least that way I can fit it all in the back of my pick up and get rid of it in a few trips to the local dump!

 

[muc]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

I’ve replaced a lot of those splined sleeves and never seen one split like that --- don’t know if that points to the cause of the failure --- just never seen one split like yours did.

You might be overly optimistic on having caught 90% of the metal. Did you pull the strainer out and check it? Can’t remember what drives had it but some of the lowers have a magnet in front of the forward gear in the lower.

The only way to get the metal shavings out is to completely disassemble and clean the complete drive.

The only way to know that the drive is shimmed right is to pattern the gears and use rolling torque to pretension the bearings.

 

[rfdfirecaptain]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

Well muc, I don't know anything about patterning gears and rolling torque. Can you recommend a site (or thread) that will walk me through this process? I was feeling pretty good about this repair until you and Don burst my bubble on this one. Seemed like a simple bad parts out good parts back in kinda job.

No I didn't check the screen yet. From what I have seen most of the shavings are very small. If you're going on the photo of the magnet plug that doesn't take into consideration all the metal the came out with the plug and feel into the drain pan as well as the metal I got out of the sleeve area itself. OK so maybe 75% is out... I was still hopful for a "flush the system" recommendation. Guess not.

I think this sleeve split when I had 8 feet of 5/8 rope wound around my props. That was over a year ago, but I am certain that put a lot of strain on that part and finally it gave way.

 

[Don S]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

Might want to do some reading in this service manual. http://www.4shared.com/file/85931397/45d46aa9/DP-D.html

 

[rfdfirecaptain]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

Thanks Don... already on it. I got that manual from you this spring when this old girl had an oil leak. From what I am reading just to disassemble and clean it throughly it will cost me a fortune in new gaskets and seals alone... not to mention that I am not experiened or qualified to do the shimming and pre-tensioning. Sigh... what a mess! Why can't anything on a boat be simple?

 

[Don S]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

A boat is a toy, so is a Ferrari. They aren't a simple car to work on, why would you think a boat is so simple to work on?

If you want a simple boat, look for a row boat and oars. Power boats take special tools, manuals, and skills to fix correctly.

 

[muc]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

Sorry Keith but I don’t know of a quick way to get that knowledge.
Most marine mechanics go to a one week class at a factory school to learn this.
The Volvo class I attended spent about 28 hours on rebuilding drives and the rest of the time on steering, transom plate and trim system.
The Volvo manual for your drive will help --- but it is written for somebody who has attended the school. If you can get a hold of an OMC King Cobra cone clutch drive manual, while you can’t use it to rebuild your drive they did a much better job of explaining the procedures and skills that you will need.

I’m not basing my opinion on the drain plug picture. I’m going with the experience of having disassembled and cleaned a lot of these drives. You would be surprised at how much metal is hidden behind the bearing cups when they are removed.

That sleeve is designed to shear at the line in the middle. It should break into two pieces --- upper and lower. And yes quite a few of them I’ve replaced were due to line wrapped around the prop. That is why I wonder what caused it to split up the side like yours did. Makes me think that maybe your lower shaft might have too much play in it.

 

[muc]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

It can be simple ---- just costs $$$$$$

 

[rfdfirecaptain]

Re: Lost Propulsion - Possible Sheared Key On Drive Shaft??? Help Don S.

Thanks for the additional info Muc... makes sense even though it's a hard pill to swallow.

Don, to answer your question... 4 years ago, the first time you helped me with this thing you never posed the questions about tools and ability. So, all this time and through that repair and a several repairs that followed I never once considered (that with your help) there was anything about this drive I couldn't fix on my own. Up until now I figured my "limitation" was your availability to respond to my threads for help.