Sterndrive Help

[B.Read]

I'm new to this site and haven't had time to search through the threads, so I'll just ask for help with my specific problem.

I'm pretty mechanically inclined, but have no experience with outdrives. I have an old 1974 Invader with an in-line 6cyl Merc 165 I/O. The outdrive seems to be the original or at least from the 70s because it has the top cap with the lift eye on top.

I was crusing at medium speed and then lost foward thrust. The boat still shifts in to forward and reverse and the prop turns, however something sounds and feels like it spinning out-of-round. Lots of vibration and terrible noises. I noticed the prop doesn't spin as freely now.

Is this an upper or lower unit problem. What are the likely causes? Where and how do you start troubleshooting. DOes anyone know of any good references, site for the do-it-yourselfer on this subject.

I'd at least like to try to fix it myself, before breaking down and spending the cash for a new or rebuilt on. The boat is too old to invest lots a cash.

Thanks for any help in advance.

 

[meesh]

Re: Sterndrive Help

Drain the oil and see if ts full of metal shavings. Pull the top cap and that will give you a look at your top gears. this does not sound like its going to end well.

 

[SS MAYFLOAT]

Re: Sterndrive Help

First of all welcome to iboats. You will find your answers here. There are some great master mechs here that can guide you through the process. Lord only knows how much they have helped me.

Get a manual as this helps a lot. I'd pull the prop first to see if the hub has spun out. If that checks out, I would pull the whole outdrive off. Once it would be off, I would check the hub that is on the flywheel to make sure it is in good shape. Then would be the gimble bearing that the drive shaft passes through to the hub on the flywheel. Then while it is out, check the universal joints and replace the waterpump impeller. If all that checks out to be okay, then a problem may lie internally.

 

[B.Read]

Re: Sterndrive Help

First let me thank you for the replies.

Sorry the update is coming late, but I haven't had time to start looking at the boat. I have downloaded the manual from the Adults Only section and taken a look at it.

I drained the oil and pulled the top cap. Findings are: No metal shavings. Gears look good and intact. The oil (not much of it) is milky. Water in the oil? I haven't pulled the prop yet. I did notice the trim tab is gone. Could the prop have knocked it off?

I also noticed the oil dripping from the bellows area. I haven't gotten a good look at them yet. The bottom is the exhaust...right?

My questions are :

When I pull the prop what should I look for? Slop/movement? Right now the prop will turn, but not as easily as before. Not binding just seems tight. Also nothing viewed from the top cap is turning when the prop turns. Should it?

Is there a check involving turning the prop with the shifter in gear. I read somewhere the prop should ratchet one way or the other?

What is the recommended next step?

 

[cr2k]

Re: Sterndrive Help

If you are running an older style prop with the rubber hub it could be slipping. But as the prop is sandwiched between the prop washer and the nut I would not think it would vibrate much. But none the less pull the prop and look to see if the splined center section looks straight front and back. Also look for signs of the rubber being less than perfect. Next item would be the engine coupler.
If you can reach around to the back of your engine and feel the shaft going to the coupler (engine off) see how far you can feel in to the bell housing.
If your hand comes back with the nastiest, stickest black goo on it for sure your coupler is shot.

This will cause vibration, but should not affect how easy your prop turns in neutral. Spin your prop and see if it has a bent shaft. You could have picked up a chunk of driftwood that went between your prop and your trim tab and broke it and may have damaged your prop and/or prop shaft. A bent prop blade can cause a vibration in the water due to not pulling evenly. If none of the above. Lower drive issues. Water in oil could result from bent prop shaft, fishing line in prop shaft seal. Is the oil in your drive bellows? (top) Are you sure its drive oil (would be milky like drive oil is as you stated) , if so input shaft seal, or it could be oil separated from the grease from your gimbal bearing.

Since you didn't mention any noises we will assume your gimbal brg. is not to blame. When/if you pull your drive stick your hand in there and rotate your gimbal brg. to see if it is silky smooth. If not replace.

That should give you enough to keep you bust for awhile. Get back to us and let us know what you find.

Always put your shifter in forward gear to pull/install the drive.

Oh yea...top gears no turn unless in gear. Always turn with engine. Shifting is done in lower case. In forward prop should ratchet clockwise (from back) and vise versa in reverse.

 

[gshldon]

Re: Sterndrive Help

Just a question here, unless i missed it earlier, what drive are we looking at on the boat??

 

[ziggy]

Re: Sterndrive Help

he's likely got a 1 drive.

the criteria your prop should meet. in
fwd=prop locks ccw, ratchets cw
neu=prop freewheels both directions, no sound no feel.
rev=prop locks cw, ratchets ccw

a few of my thoughts.
you should have lub in your drive, not a little milky looking lub. the fact that you have a little milky lub to me means an leak somewhere. the fact that lub is dripping from your bellows area leads me to think the ft. seal of the drive is bad. what makes that seal go bad is water intrusion into the bellows area. if water gets in the bellows, it's free to get into the drive via the ft. seal in the drive. this water rust's everything it touches. the yoke where the ft. seal rides is succeptable to rust which then eats up the seal for not having a smooth surface to ride on. assuming ya had water in the bellows, you'll need to R&R the ujoints and gimble brg. and likely the yoke and ft. seal. you'll also need to address the bellows if that's how water got into your drive. assuming that's where the water came from that's in your drive.
you can also pressure test your drive. this will help find a leak in your drive. could be something simple like 2 gaskets on a drain or vent screw, or the ft. seal of the drive, or other seals too.

your lack of being able to get fwd or rev. could be the prop hub. but from your description, you've got more problems than that.

i think i'd start by pulling the drive and see what ya got there. coupler spline inspection, rusty's inspection, bellows inspection. pressure test.

after the drives off. might as well separate the upper and lower. you'll be able to spin the upper and see if the drive shaft on the driven gear turns when ya turn the drive shaft.

you'll be able to see if shifting still occurs when you have the lower separated and off the boat, it should stilll meet the criteria above.

have ya done any pm to this drive in recent history?

you can pressure test the halves of the drives too once separated.

pulling the prop is gonna be the easy part from your description. i think it sounds like you've got troubles somewhere... time for some inspections...

all shifting is done in the lower.

all parts should be moving when the engine is running. except the prop shaft when in neutral.

 

[B.Read]

Re: Sterndrive Help

Thanks for all the suggestions! Sorry for failing to mention the drive type. I seem to have a pre-alpha Mercruiser I-Drive. The boat is a 1974 and seems to have the original motor and drive.

As far as PMs. I just recently bought the boat used. I took it to a mechanic to have the carb re-built because it was running rough. I had replaced the engine oil, plugs, plug wires, points, etc. I also had replaced the fuel tank. I asked him to give it a good look over, but I guess he didn't do so good. I'm learning this boat thing the hard way.

Another update.

I have gotten a better look at the bellows area. All three bellows are shot. Big splits. The shifter cable bellows is in 2 halfs as is the exhaust bellows. The top bellows is split so wide I can see the u-joint from both sides. The drive oil is dripping on top of the exhaust bellows, so I assume this is coming from the u-joint area. I also assume this is how the water got in.

I'll pull the prop and the drive when I get a chance this weekend and get back to everyone on what I find.

One question. When the problem occurred the engine ran smooth in Neutral. When put in gear, the whole boat shook relative to RPM. The best way to describe it is: What I would expect it to feel like if my flywheel was oblong or weighted on one side. My gut tells me the problem is something out of round. Could this be the coupler or a bent prop shaft?

 

[Zeeter]

Re: Sterndrive Help

One question. When the problem occurred the engine ran smooth in Neutral. When put in gear, the whole boat shook relative to RPM. The best way to describe it is: What I would expect it to feel like if my flywheel was oblong or weighted on one side. My gut tells me the problem is something out of round. Could this be the coupler or a bent prop shaft?

The coupler is gone.

 

[bigskiohio]

Re: Sterndrive Help

pull the drive you will need to do that anyways, if it is the coupler easy ,cheap fix. bellows will be some work. i read this problem over and over but i almost never hear anybody say they checked there outdrive oil before they went out.
it takes 10 min at most to pull the drain to see if there is water in oil,then top it off. i use merc+ at 15.00 a quart but if you dont have any major problems
you wont use much just till it comes out vent hole. i had a 1969 evinrude sportsman a friend gave me because he repainted boat redid int. rebuilt engine and synced both carbs and then fried omc outdrive on first day because he never checked the oil. i gave that boat away what a idiot it had a dual carbed 4cyl he said engine was same as cosworth vega but i still dont know if that was right.but it looked nothing like my merc 120.
never seen one like that

 

[B.Read]

Re: Sterndrive Help

Thanks to everyone for the help and advice. I'm scheduled for shoulder surgury so I'll probably wait until I recover before getting started with any further repair. Don't want to damage me or the drive trying to pull it with a gimp shoulder.

I'll get back with an update once I have the drive pulled.

 

[B.Read]

Re: Sterndrive Help

Despite my previous post, I went ahead and pulled the drive before having my surgury. I pulled the prop and separated the upper and lower units.

Findings:

1) The coupler seems to be OK. (There is no sticky goo to be found.) The area around the back of the engine seems clean. Any other checks I can do for it?

2) The U-Joint and shaft splines look good and move freely (no slop)

3) The upper unit turns freely with no binding.

4) Looking into the bell housing there is obvious water intrusion. As mentioned previously the bellows ( all three) are split open. The upper bellows (u-joint area) still has some fresh lube and water mixed (mostly water) puddled in the bellows. The water hose looks like it's cracking (dry rot look).

5) The lower unit turns, but with a lot of resistance. The gears wear placed all the way forward when I pulled the drive. The prop will turn forward and clicks, but it's hard to spin.

6) Overall, it looks as if the unit has been very low on lube and had water intrusion.

Any suggestions on what I should check in the lower unit and how to go about it?

It goes without saying I need to replace the bellows, water hose, gaskets, etc. I might as well replace the impeller and the U-Joints while I have it apart. Any other suggestions?

 

[rockyman]

Re: Sterndrive Help

i have the same set up in my 1981 galaxy and i also had some of the same problems that you are having . the outdrive has a couple of barings in it one in the upper and one in the lower, if either one of those goes bad you will feel it in the prop ,you will also get shavings in your oil but in order to see them you will have to drain your outdrive oil .

 

[BLDFW]

Re: Sterndrive Help

Gosh.....and WOW....I've seen only one suggestion to check the prop. Everyone else wants you to spend a bucket load of money.......and likely unnecessarily. Before you do anything else or spend any more money....PULL THE PROP and check it out or have someone else do it.

If you can put your outdrive in forward or reverse gear at an idle...and get forward or rearward movement....but then when slowly increasing RPM's suddenly you lose momentum and the rpm's begin to climb, then likely you have spun the prop. The vibration you suggested could be just the unevenness of the internal core spinning inside the prop. It's not always visible but the above steps will help validate whether it's the hub or not.

The prop has a center rubber core or plug that can only be inserted by a powerful machine. The rubber core is molded or glued to the center shaft and pressed into the prop shell. The rubber expands to press against the outside of the prop shell. This design protects the expensive outdrive components when hitting an obstruction. It's designed to break free protecting the internal gears. Unfortunately the rubber inside the hub can shear simply because it's OLD. When pressure of the increased RPM's become to great for the friction and pressure of the rubber core, it will let go and start free spinning inside the core. When that happens it can scare the crap out of you!!

Sounds like so far you have checked everything except the prob core. They are easily replaced and fairly inexpensively, probably less expensively than all of the diagnostics that have gone on thus far.

 

[BLDFW]

Re: Sterndrive Help

Despite my previous post, I went ahead and pulled the drive before having my surgury. I pulled the prop and separated the upper and lower units.

Findings:

1) The coupler seems to be OK. (There is no sticky goo to be found.) The area around the back of the engine seems clean. Any other checks I can do for it?

2) The U-Joint and shaft splines look good and move freely (no slop)

3) The upper unit turns freely with no binding.

4) Looking into the bell housing there is obvious water intrusion. As mentioned previously the bellows ( all three) are split open. The upper bellows (u-joint area) still has some fresh lube and water mixed (mostly water) puddled in the bellows. The water hose looks like it's cracking (dry rot look).

5) The lower unit turns, but with a lot of resistance. The gears wear placed all the way forward when I pulled the drive. The prop will turn forward and clicks, but it's hard to spin.

6) Overall, it looks as if the unit has been very low on lube and had water intrusion.

Any suggestions on what I should check in the lower unit and how to go about it?

It goes without saying I need to replace the bellows, water hose, gaskets, etc. I might as well replace the impeller and the U-Joints while I have it apart. Any other suggestions?

I guess I missed it and my suggestions comes too late. Sorry you had to go through all that for likely a spun prop. Ah well......

 

[B.Read]

Re: Sterndrive Help

Thanks for the suggestions Bill. I'm new at this, but would the spun prop theory cause the lower unit to not turn freely. I have the lower unit completly detached. When I turn the prop it's very hard to turn and I see no movement on the drive shaft coming out of the top. I'm guessing due to lack of lube and contaiminated lube at that, I have some sort of frozen bearing/s on the prop shaft or drive shaft of the lower unit.

Any thoughts?


How can I check the spun prop visually?

 

[B.Read]

Re: Sterndrive Help

Update

I found a complete upper and lower unit on Craigslist for $200. The guy boat a boat and the impeller went out so he cracked a head on the engine. He parted the boat out rather than fix it.

The difference between how my low unit turns and the replacement is night & day.

My problem is definately a frozen bearing or bent shaft in the lower unit.

Any advice on how this thing goes back on?