# I/O jumping out of gear (I think)



## bajuski (Apr 9, 2004)

I have a 1985 4 winns alpha one gen 1 and the last few years on occasion the boat would give a loud hard thump when I throttled up from a standstill. My last trip in December it got really bad, it revved up, banged in gear several times before i cut the throttle and made it slowly back to the launch at trolling speed. After reading some of the older posts here I was convinced that the forward gear and clutch dog gears are shot so I took it apart and to my surprise, nothing wrong! The teeth on the side are just a little shiny on the tips but not rounded at all. The shifter is centered perfectly in forward gear just like it's supposed to and the prop locks in both directions.. Also, I replaced the coupler last year so that can't be it. The shift cables are adjusted properly and work smoothly. Could a spun prop do this, I mean it's a scary bang when it catches at high rpm. I hope someone can help me, I'm at a loss, Thanks


----------



## sherman51 (Apr 12, 2011)

I would try another prop then if that doesn't fix the problem i'd have a new shift cable installed. sometimes the old shift cable stretches and you cant get them adjusted right.
sherman


----------



## firemanmike2127 (Mar 17, 2013)

It definitely sounds like it's jumping out of gear. Did you closely examine the lugs on the clutch dog & forward gear ? The mating lugs on the forward gear should have a consistent 90° 'shoulder'.....not a rounded appearance. Same thing goes for the clutch dog (shifter). They usually have a very small but distinct (appx 1/16") bevel on the corner of the 90° mating surface. An improperly adjusted or worn out intermediate shift cable can contribute to this condition. It's absolutely imperative that you determine why this problem occurred in the first place. I'd recommend that you find a reputable Mercruiser technician to examine the gearcase internals & the overall condition of the shifting linkage prior to putting the gearcase back together. There's also a shift interrupter switch that needs to work properly so you don't damage the shifter & cables when you are shifting from forward/reverse into neutral. Mike


----------



## bajuski (Apr 9, 2004)

firemanmike2127 said:


> It definitely sounds like it's jumping out of gear. Did you closely examine the lugs on the clutch dog & forward gear ? The mating lugs on the forward gear should have a consistent 90° 'shoulder'.....not a rounded appearance. Same thing goes for the clutch dog (shifter). They usually have a very small but distinct (appx 1/16") bevel on the corner of the 90° mating surface. An improperly adjusted or worn out intermediate shift cable can contribute to this condition. It's absolutely imperative that you determine why this problem occurred in the first place. I'd recommend that you find a reputable Mercruiser technician to examine the gearcase internals & the overall condition of the shifting linkage prior to putting the gearcase back together. There's also a shift interrupter switch that needs to work properly so you don't damage the shifter & cables when you are shifting from forward/reverse into neutral. Mike



You're exactly right, that's why I don't get it, the sliding clutch dog gears and the forward gear are cut to over 90 degrees and once the gears mate they are supposed to draw together. That's why you need a shift interruptor, to get them apart. As far as the lower gearcase, it is as basic as I've seen, shimming would be tricky. But I'm not replacing any parts so I won't need to re shim.
I'd better take a look at the upper gears, what I should have done in the first place but dummy me has to start with the hardest!


----------



## bajuski (Apr 9, 2004)

sherman51 said:


> I would try another prop then if that doesn't fix the problem i'd have a new shift cable installed. sometimes the old shift cable stretches and you cant get them adjusted right.
> sherman


I am going to replace the prop Sherman, it does show a little evidence if slippage, it looks like it may be slightly burned around the rubber outer edge. I wouldn't think that it would slam in and out like this thing though!


----------



## sherman51 (Apr 12, 2011)

I made a trip to erie a couple of yrs ago and when we launched the boat it wouldn't go into reverse at all. we took it to the shop in the back of the Geneva marina. he adjusted the cable and got it shifting ok. but after about 2 trips on the water it started doing the same thing. so I had a new shift cable installed, and its been doing good ever since then. a stretched cable can cause a lot of problems.

please keep us up to date on your progress.
sherman


----------



## bajuski (Apr 9, 2004)

sherman51 said:


> I made a trip to erie a couple of yrs ago and when we launched the boat it wouldn't go into reverse at all. we took it to the shop in the back of the Geneva marina. he adjusted the cable and got it shifting ok. but after about 2 trips on the water it started doing the same thing. so I had a new shift cable installed, and its been doing good ever since then. a stretched cable can cause a lot of problems.
> 
> please keep us up to date on your progress.
> sherman


I will Sherman, I won't know until I put it in the water though. I replaced the cable quite a while ago but it's ok. With the control in fwd gear the prop locks turning counterclockwise and locks in reverse turning clockwise, neutral the prop just spins so the shaft is engaging the gears like it's supposed to.


----------



## firemanmike2127 (Mar 17, 2013)

Let's assume thr upper gear set is OK since you didn't mention the presence of metal shavings in thr gear oil. A slipping prop will cause excessive engine RPM or not even allow the boat to accellerate in some cases. You can put a couple of index marks on the front side of the inner hub & the outer portion of the prop
After running the boat remove the prop & check the relationship of the marks. They should not move. I'd look at the cable adjustment very closely. There is a very specific process to go through in the service manual. You can probably find some good videos on YouTube also, but I would advise you to verify the procedure with the proper book. The initial measurement of the intermediate shift cable (the one that connects to the gearcase linkage) is done with the unit shifted into full forward gear. This is a critical step & you need to verify that the specified dimension is correct. There is also a slot in the linkage & in a lot of older equipment there have been additional adjustments utilizing that slot to 'compensate' for improper cable adjustment or worn shifting components. I've replaced quite a few of these cables & have seen this more than once. Mike


----------



## sherman51 (Apr 12, 2011)

lets just hope its something as simple as the prop hub. then you can have another one pressed in.

firemanmike gave you good advice about marking the hub and the outer part of the prop to check for slippage if you don't have another prop you can try. I have a couple of spare props I keep in my boat. if I lived closer to you I would let you use one to see if that's the problem. if you don't have an extra prop maybe someone closer to you would be willing to let you borrow one. most mercury v6 outboards have the same prop as a mercruiser.
sherman


----------



## bajuski (Apr 9, 2004)

I did check the cable end distance, it is 6 inches, just as the manual says it should be. Here's a pic of the clutch jaws and forward gear, can it be jumping in and out without destroying the clutch and fwd gear jaws? Maybe I'm wrong all I see is normal wear. The gears in the upper are ok also, but after seeing how little movement it takes to shift gears I checked the shift shaft and did find quite a bit if movement, gonna have to find out where the slop is! What do you think, about the gears I mean


----------



## backfar (Sep 24, 2014)

Its probably not the prop slipping.the whole point of rubber pressed into prop is to aviod sharp blows to outdrive if the prop hits something...i would have somebody experienced with the shift cable adjustment look at it...i had a new shift cable put on last year and it took 3 different times to get it working properly...hope you find the problem...keep us posted


----------



## backfar (Sep 24, 2014)

I will add that the only way to truly adjust the cable is with the boat in the water....the mechanic that did mine was a authorized merc guy...and it still had issues not wanting to come outta gear after using the boat for a day....but after 3 time its all good...hope this helps


----------



## KaGee (Sep 8, 2006)

The clutch dog looks good as pictured. I agree with the prop hub probably not the cause. When you go to power up and the RPMs raise quickly and you go no where, that's typically a prop hub.


----------



## RJohnson442 (May 14, 2013)

Check your gimbal bearing and motor alignment along with the inner and outer housing make sure everything is tight and aligned. I had a similar problem once started with the knock in and out of gear on the way out, that turned to a slipping out of gear while on the water that went to a full turn would kill the motor on the way back in. The result was because of the gimbal bearing freezing to the shaft and milling the gimbal housing to to nothing. Everything was junk at that point. New bellows and bearing, no sign of water intrusion, The mechanic and I both agreed it was either a faulty bearing or the motor was not aligned and the bearing seized to the shaft. If you were in some hard stuff last year it's worth looking at.


----------



## KaGee (Sep 8, 2006)

RJohnson442 said:


> Check your gimbal bearing and motor alignment along with the inner and outer housing make sure everything is tight and aligned. I had a similar problem once started with the knock in and out of gear on the way out, that turned to a slipping out of gear while on the water that went to a full turn would kill the motor on the way back in. The result was because of the gimbal bearing freezing to the shaft and milling the gimbal housing to to nothing. Everything was junk at that point. New bellows and bearing, no sign of water intrusion, The mechanic and I both agreed it was either a faulty bearing or the motor was not aligned and the bearing seized to the shaft. If you were in some hard stuff last year it's worth looking at.


I was thinking this earlier when he said he installed an engine coupler. Did he use an alignment tool when he re-installed the drive? As I recall an unaligned shaft will usually be the source of the coupler going bad.


----------



## bajuski (Apr 9, 2004)

KaGee said:


> The clutch dog looks good as pictured. I agree with the prop hub probably not the cause. When you go to power up and the RPMs raise quickly and you go no where, that's typically a prop hub.


I agree KaGee, but since I'm into it this far I ordered a new prop from Iboats anyways. I'm confident that the drive will be ok. It went together a lot easier than it came apart with all the corroded retainers and threads cleaned up. It goes to show you though, it's worth to pay the price for the mercruiser gear oil, I couldn't believe the nice shape the gears were in.


----------



## bajuski (Apr 9, 2004)

KaGee said:


> I was thinking this earlier when he said he installed an engine coupler. Did he use an alignment tool when he re-installed the drive? As I recall an unaligned shaft will usually be the source of the coupler going bad.


I didn't use an alignment tool, but I did use an old driveshaft from an upper drive that went bad about 10 years ago and it slid right in.


----------



## firemanmike2127 (Mar 17, 2013)

firemanmike2127 said:


> The initial measurement of the intermediate shift cable (the one that connects to the gearcase linkage) is done with the unit shifted into full forward gear. This is a critical step & you need to verify that the specified dimension is correct. There is also a slot in the linkage & in a lot of older equipment there have been additional adjustments utilizing that slot to 'compensate' for improper cable adjustment or worn shifting components.


 Let's back up here for just a second. First, this piece of equipment is 21 years old & has probably seen a considerable amount of use after that many boating seasons. Now, let's discuss the shift linkage. The intermediate cable has to move the clutch dog through a number of different components. The cable provides linear motion (slides back & forth). At the end of the cable is a shift slide which is connected to an upper shift shaft, then a lower shift shaft, & then a bell crank, which is at the front end of the prop shaft. All four of those linkage parts have to rotate together during each shifting cycle. The bell crank mates to a brass shift spool & shaft that is connected to the clutch dog, & makes it slide back & forth (linear motion). There can be a lot of "lost motion' when you think about all those parts that are involved. Even though the initial intermediate cable dimension is correct (6" in forward), there is high probability of worn shifting components, INCLUDING the intermediate shift cable (unless it has been replaced in the last few years). I'd pop the drive back off & perform a thorough inspection.....something caused this problem. I've spent many hours in my shop working on Mercruiser stern drives & they don't jump out of gear for no good reason. I'm not trying to sound like a know-it-all here, but I've been down this road before. If the clutch dog & gears are still in good condition, you've been lucky so far. Maybe I missed something in one of your earlier posts on this thread, but I don't think you're ready for the water just yet. Good luck & keep us posted on your progress. I'll include my # if you want to ask any questions. Mike Bruns 419-305-8111


----------



## bajuski (Apr 9, 2004)

firemanmike2127 said:


> Let's back up here for just a second. First, this piece of equipment is 21 years old & has probably seen a considerable amount of use after that many boating seasons. Now, let's discuss the shift linkage. The intermediate cable has to move the clutch dog through a number of different components. The cable provides linear motion (slides back & forth). At the end of the cable is a shift slide which is connected to an upper shift shaft, then a lower shift shaft, & then a bell crank, which is at the front end of the prop shaft. All four of those linkage parts have to rotate together during each shifting cycle. The bell crank mates to a brass shift spool & shaft that is connected to the clutch dog, & makes it slide back & forth (linear motion). There can be a lot of "lost motion' when you think about all those parts that are involved. Even though the initial intermediate cable dimension is correct (6" in forward), there is high probability of worn shifting components, INCLUDING the intermediate shift cable (unless it has been replaced in the last few years). I'd pop the drive back off & perform a thorough inspection.....something caused this problem. I've spent many hours in my shop working on Mercruiser stern drives & they don't jump out of gear for no good reason. I'm not trying to sound like a know-it-all here, but I've been down this road before. If the clutch dog & gears are still in good condition, you've been lucky so far. Maybe I missed something in one of your earlier posts on this thread, but I don't think you're ready for the water just yet. Good luck & keep us posted on your progress. I'll include my # if you want to ask any questions. Mike Bruns 419-305-8111


I adjusted the cables a few weeks ago Mike, it was out, it was at 5 1/2 instead of 6 inches. I did have to move the lower shift cable end on in the slotted hole upwards to get it to go in reverse. After adjustment, it engaged in fwd and ratcheted as it's supposed to, same in reverse, it engaged and ratcheted and neutral was right where it's supposed to be.
As I described earlier, it was really pounding my last trip out and since I had the lower off to replace the impeller, I wanted to make sure the gears weren't ruined, especially this early in the year with no one out there to help you. It took an god awful pounding and I'm surprised that the gears aren't even rounded or missing teeth. I didn't replace anything in the gearbox so I didn't have to reshim. It would cost me more money buying the proper tools than to replace the whole outdrive with an Se, which I will do if this doesn't work out, the boat is 31 years old but it's always been garage kept and is solid structurally and me at 69 years old,a new boat would be a waste.. Sorry for not being more clear.


----------



## ErieIslander (Jul 12, 2012)

I had a similar problem with my 1988 Starcraft Islander 221V hardtop. It has the original OMC Cobra outdrive and never had a problem after 25+ years of use and abuse on Erie. However, all good things eventually come to an end. 
2 years ago when I tried to get on plane to head back to the marina after a long day of trolling, the outdrive began to "thump" when trying to get on plane. It felt like someone was beating the hell out of the bottom of my boat with a sledgehammer. The odd thing was i finally was able to get on plane and made it back to the marina. I mean to tell you it took 10+ or more attempts to get it on plane and I was at the border fishing the buoy in July.
I ended up removing the outdrive and separated the upper from the lower unit. The problem was in the lower unit. The main largest bearing was bad and was allowing the largest gear to actually hit the inside wall of the lower gear case. I ended up purchasing an inexpensive used outdrive with a good matching lower unit. I replaced all seals and and mated the the new lower to the existing upper. Replaced all cables and have been fishing ever since with no thumping or popping out of gear.


----------



## bajuski (Apr 9, 2004)

ErieIslander said:


> I had a similar problem with my 1988 Starcraft Islander 221V hardtop. It has the original OMC Cobra outdrive and never had a problem after 25+ years of use and abuse on Erie. However, all good things eventually come to an end.
> 2 years ago when I tried to get on plane to head back to the marina after a long day of trolling, the outdrive began to "thump" when trying to get on plane. It felt like someone was beating the hell out of the bottom of my boat with a sledgehammer. The odd thing was i finally was able to get on plane and made it back to the marina. I mean to tell you it took 10+ or more attempts to get it on plane and I was at the border fishing the buoy in July.
> I ended up removing the outdrive and separated the upper from the lower unit. The problem was in the lower unit. The main largest bearing was bad and was allowing the largest gear to actually hit the inside wall of the lower gear case. I ended up purchasing an inexpensive used outdrive with a good matching lower unit. I replaced all seals and and mated the the new lower to the existing upper. Replaced all cables and have been fishing ever since with no thumping or popping out of gear.


Glad it worked out for you ErieIslander, I had a similar experience at the sandbar about 10 years ago only my upper went, it started squeeling while trolling then screaming, lol. I made it back 8 miles to hotwaters though. The upper gears were destroyed so I replaced the whole outdrive with a used drive and saved the lower internal parts so I have them if needed, but everything looks ok to me! I fully expected to see something like you found.


----------



## ErieIslander (Jul 12, 2012)

bajuski said:


> Glad it worked out for you ErieIslander, I had a similar experience at the sandbar about 10 years ago only my upper went, it started squeeling while trolling then screaming, lol. I made it back 8 miles to hotwaters though. The upper gears were destroyed so I replaced the whole outdrive with a used drive and saved the lower internal parts so I have them if needed, but everything looks ok to me! I fully expected to see something like you found.


Thanks bajuski. Glad it worked out for you as well. I try to do all repairs myself to keep fishing affordable.


----------



## bajuski (Apr 9, 2004)

Well, finally got it on the water today and even got a little perching in. The outdrive runs great on the muffs and on the water. I can now punch it from a standstill to full throttle and it stays in gear. I have a brand new prop now but did not put it on yet just to make sure but it definately was not the prop, simple adjustment of both the lower and the control cable. At least I know what I have now, thanks for your thoughts!


----------



## sherman51 (Apr 12, 2011)

bajuski said:


> Well, finally got it on the water today and even got a little perching in. The outdrive runs great on the muffs and on the water. I can now punch it from a standstill to full throttle and it stays in gear. I have a brand new prop now but did not put it on yet just to make sure but it definately was not the prop, simple adjustment of both the lower and the control cable. At least I know what I have now, thanks for your thoughts!


sure glad you got it working. fishing season is up on us, and don't want your boat to be down while others are fishing.

we were up to Geneva last july and was only out about 6 miles when my upper crashed. had to call boat us and get towed in. found a great marina that sold us a used outdrive and installed it for 750.00. and we were back on the water fishing in a couple of days.
sherman


----------



## Misdirection (Jul 16, 2012)

bajuski said:


> Well, finally got it on the water today and even got a little perching in. The outdrive runs great on the muffs and on the water. I can now punch it from a standstill to full throttle and it stays in gear. I have a brand new prop now but did not put it on yet just to make sure but it definately was not the prop, simple adjustment of both the lower and the control cable. At least I know what I have now, thanks for your thoughts!


I would keep the prop as a spare on the boat. Make sure you have a spare nut, washer, cotter pin and any necessary tools in case you have to change it out in the lake. And if you do have to change it out in the lake, wear a life jacket and tether yourself to the boat!

Glad you got the jumping out of gear fixed.


----------



## bajuski (Apr 9, 2004)

sherman51 said:


> sure glad you got it working. fishing season is up on us, and don't want your boat to be down while others are fishing.
> 
> we were up to Geneva last july and was only out about 6 miles when my upper crashed. had to call boat us and get towed in. found a great marina that sold us a used outdrive and installed it for 750.00. and we were back on the water fishing in a couple of days.
> sherman


That's a hell of a deal you got for $750 installed. I paid almost that when my upper crashed about 10 years ago and I had to install a new water pump on it too because I didn't know what shape it was in. 
I learned one thing about Alpha ones, they call for 32 ounces of fluid so you'd better not lose a drop if you're filling from the bottom. I always have extra oil now and pop the top cap to make sure the level is up there covering the gears!


----------



## bajuski (Apr 9, 2004)

Misdirection said:


> I would keep the prop as a spare on the boat. Make sure you have a spare nut, washer, cotter pin and any necessary tools in case you have to change it out in the lake. And if you do have to change it out in the lake, wear a life jacket and tether yourself to the boat!
> 
> Glad you got the jumping out of gear fixed.


Good advice Misdirection. I have a brand new prop and hardware and fully intend to put it on before I go again, I just left the old one on for trouble shooting and had the new one with me in case it would still be jumping out of gear. I would not have changed it on the water though, I would have put the boat back on the trailer.
It was kind of stupid for me to check it out yesterday though, I was the only trailer in the lot, going out in fog with not knowing for sure that I had a reliable drive. I had to use my compass to get back, I do have a gps but didn't have to use it. And I caught a few perch.


----------



## ErieIslander (Jul 12, 2012)

sherman51 said:


> sure glad you got it working. fishing season is up on us, and don't want your boat to be down while others are fishing.
> 
> we were up to Geneva last july and was only out about 6 miles when my upper crashed. had to call boat us and get towed in. found a great marina that sold us a used outdrive and installed it for 750.00. and we were back on the water fishing in a couple of days.
> sherman


Post the repair shop info if you remember. Always looking for a good recommended place.


----------

