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hard to shift into and out of gear

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46international

New member
I have a 1996 mercury 135hp outboard. motor has 495 hrs. I bought it new and it has been a good motor but the last year of so after hitting a sandbar (if you have boated in Ocean City Maryland you will know how this happens) it is very hard to shift into of out of gear, just cannot move the control lever. after you get it in netural and run for a while it shifts fine again. Anyone have an idea what is going on?
 
If it were linkage..hard metal to hard metal, I'd think it would be constant. Inside the lower unit is the drive shaft, some seals and bearings, the prop shaft and the drive shaft pinion gear which drives the rear of F and R gears.

F and R gears spin as long as the flywheel is turning, hard metal to hard metal.

The prop shaft couples to those gears via a "shift dog" which is locked to the prop shaft for rotational aspects but the locking mechanism is spring loaded and has a slot in the prop shaft whereby the dog can move back and forth. The dog is what connects the spinning F and R gears to the prop shaft.

The movement is controlled by your shift shaft which connects in the LU to a shifter cam. This cam has 3 detents representing F N R gear positions. On the front of the prop shaft is a "cam follower" which rides in and out of these detents as one selects a gear. Inside of this cam follower is a spring that pushes against the clutch dog and this spring pressure either allows the dog to rest in the rear of F gear, with a little more pressure in mid position for N gear where the teeth on the dog don't connect to F or R gears, and the third follower position with maximum pressure against the spring, pushes the dog to the rear and engages R gear.....that's how it works.

I don't know what happened when you hit the bar nor what you did then or later but my guess is that the dog is damaged. I'd do some general testing to get a better feel of what it is and isn't doing or supposed to be doing before I tore into it but removing the prop shaft isn't that bad of a job...just keep track of what you take out and where it was...a parts breakdown picture helps in doing that. The teeth on the F and R gear are hardened steel and are probably ok. I think the dog is bent or has damaged teeth and that accounts for why sometimes it works and sometimes it doesn't.

If it's like I'm thinking, a couple of bolts hold the R bearing carrier into the LU housing...Pulling that out allows you to work the prop shaft out...being careful to watch for shims and remember where they were...shims, large like 4" in diameter.....F gear and any shims associated with it should stay in the LU in position if you are careful...even if it falls down no biggie to put it back into its bearing in the nose of the LU.

With the prop shaft in your hand you can examine the cam follower bullet nose for a non marred blunt conical end and examine in particular the clutch dog and the front and rear gears on it.....also checking that forcing against spring pressure, the dog slides easily back and forth on the prop shaft. If the gears on the dog are dinged up pretty good you might check the teeth on the back of F and R gears too.
 
Great, thanks for the great reply.
I have had the lower unit apart before to replace seals etc.. This was about 4 years ago and I don't remember if I had this problem at that time or not, maybe just slightly. This is something that just seems like is just getting worse, starting lowly. My profession is heavy equipment mechanic. The problem is that after hitting a sandbar lightly it will be just a little hard to shift into neutral from forward and a little hard to shift from neutral to reverse. And the harder you hit the sand bar, the harder it is to make those shifts. Most of the time I will hit bottom going very slowly trying to get to the right spot for fishing or starting off after drifting onto the bar.
This last bar we hit was bad, real bad and I could not even move the throttle back to idle. Now, after I get it back in neutral, restart, and run for a while all is good again, easy shifting and throttle. Correct me if you think I'm wrong, but if there was damage to the shifting parts in the LU, would it not be hard to shift all the time? Also, this last time, I could not even pull the throttle down, right, the throttle would not move. The shifter linkage does not even move until the last part of throttle travel, right? If it was a cable or lube point problem, it would be all the time also. thoughts?
Just one more thing, before everyone thinks I spend all of my time grounded, I really don't, this is a 1996 motor on a 1996 boat that I bought new and it has the original prop on it. There is a saying in Ocean City, there two types of people in Ocean City, one that has been on sand bars and others that don't have boats!
 
If I understood you post correctly, this issue is intermittent. I would start by checking the lower mounts on the mid section.... Make sure the shift shaft is not up against the Steering arm swivel pin.... This is the tube the shift rod passes through... The rod should be close to the center. If the mounts are broken with rotten hardware the mid section will move forward and back and pinch the shift rod.
 
46international said:
Great, thanks for the great reply.
I have had the lower unit apart before to replace seals etc.. This was about 4 years ago and I don't remember if I had this problem at that time or not, maybe just slightly. This is something that just seems like is just getting worse, starting lowly. My profession is heavy equipment mechanic. The problem is that after hitting a sandbar lightly it will be just a little hard to shift into neutral from forward and a little hard to shift from neutral to reverse. And the harder you hit the sand bar, the harder it is to make those shifts. Most of the time I will hit bottom going very slowly trying to get to the right spot for fishing or starting off after drifting onto the bar.
This last bar we hit was bad, real bad and I could not even move the throttle back to idle. Now, after I get it back in neutral, restart, and run for a while all is good again, easy shifting and throttle. Correct me if you think I'm wrong, but if there was damage to the shifting parts in the LU, would it not be hard to shift all the time? Also, this last time, I could not even pull the throttle down, right, the throttle would not move. The shifter linkage does not even move until the last part of throttle travel, right? If it was a cable or lube point problem, it would be all the time also. thoughts?
Just one more thing, before everyone thinks I spend all of my time grounded, I really don't, this is a 1996 motor on a 1996 boat that I bought new and it has the original prop on it. There is a saying in Ocean City, there two types of people in Ocean City, one that has been on sand bars and others that don't have boats!
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I'm still thinking the dog is dinged up. I think you banged it possibly generating a burr that had a wedging effect on the rear of whatever gear you were in, or within the interface of the dog to the prop shaft pin/slot. I feel that your working the linkage got the "jam" unstuck and subsequent shifting continued to "grind off" the burr. I would expect to find cracks, or corners rounded off, or bent mesh components within the dog, including the interface between the dog and the prop shaft.
 
You may be right, the boat is at my Daughter's house and it will be until this weekend when I can get up there to check it out. I hope it is just the lower mounts, I was looking at the factory service manual last night and can see how those mounts could cause the problem. If not the mounts, I'll have to look at the shift dog, like you said.
Thanks
 
Docksidemarineservices said:
If I understood you post correctly, this issue is intermittent. I would start by checking the lower mounts on the mid section.... Make sure the shift shaft is not up against the Steering arm swivel pin.... This is the tube the shift rod passes through... The rod should be close to the center. If the mounts are broken with rotten hardware the mid section will move forward and back and pinch the shift rod.
Click to expand...

I like that suggestion. I agree on check there first...since he commented that hitting bars frequently is the norm, the engine being a 1996 yearmodel, they probably are damaged from numerous strikes and finally broke.
 
Yes I expect to see the bolts pulled through the rubber mount. I hope to get up to the boat this weekend to check it out. Thanks again for the help and I will let you all know what I find.
 
46international said:
Yes I expect to see the bolts pulled through the rubber mount. I hope to get up to the boat this weekend to check it out. Thanks again for the help and I will let you all know what I find.
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Just have some help and a pry bar to see if, and how much, you can move the mid section at the lower mounts.
 
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ok, I got up to look at the boat yesterday and it looks like the lower mounts have been pulling out. The bolts are not broken or rusted but it looks like the rubber is pulling out of the outer metal "ring". So, I have two questions.
First can I get these mounts out and in without removing the top mounts? I have the Factory service manual and it just covers removing the mid-section and reinstalling it and to do that you must remove the top/upper mounts. I took the plastic cover off and then removed the mount retainer and can see how they come out but I'm not sure I can get the bolt out of the bottom yoke. it may be longer than the amount of distance that I can flex the mid-section back leaving the top/upper mounts in place. I was thinking, if that is the case, I can just cut the bolts and install new ones in the other direction, thoughts?
Second, I have the parts book and it lists different mounts for a (135/150/175 long) and a number for (all other models). Problem is, I never knew this motor to be anything other than a "standard" length motor. I see in the parts book they list a "long" and a "x-long" drive shaft housing. So am I to believe that there was only a "long" and a "x-long" length and no "standard"? So I would need the mounts for the (135/150/175 long)?
Thanks again
 
To change the lower mounts the factory way, means you have to pull the power head..... I didn't tell you this but..... You can cut the bolts and remove all the bad parts.. Re install everything and reverse the bolts.... Trim any excess threads sticking through the lock nut....


I don't thing the length of the mid section has anything to do with choices on the mounts and hardware.... I think they are all the same.
 
Thanks, That was my plan, to cut the bolts off and replace with new installed the other way.
About the length, My parts book lists two different mounts so I guess I will have to figure out what I have.
 
I have a 60 hp mercury tracker. The shifting is very stiff going into and out of reverse. I disconnected cables and that is not the issue. What else do I need to look at
 
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