200, 20hp shifting problem

[Bob1957]

I recently bought a 1974 tiller steer short shaft motor for my fishing boat and am having trouble with shifting into reverse. Was told by the owner that he had hit a rock with the motor and had it repaired while on a trip to Canada. Shortly after returning home he lost reverse on the motor and was told by a dealer, not Mercury, that it would cost $150 plus to fix it.
Here is what I have found so far. The first thing I noticed was that the LU was in neutral when the shift lever was in reverse, neutral was forward with limited throttle and forward was the normal forward gear with full throttle operation. I pulled the LU and placed the shift lever and LU in reverse, reassembled the motor and was able to have normal gear and throttle operation for a few cycles through the shift pattern before it returned to it's previous state. I believe the reverse cam lock is wore out as there is a clicking noise coming from that area when attemting to shift into reverse.
I have called a local dealer to get the part and all they have is a plastic cam. Also when manually shifting the LU, off the motor, into reverse it sems to be a little tougher than I think it should be.
Questions:
Is the cam for this motor available in metal or is that only for larger motors?
Is it possible that when the LU was repaired something was missed and/or installed incorrectly causing hard shifting into reverse?
Serial number for the motor is 4056648. The motor runs great and obviously has been used very little. I got a great price on it and am willing to spend some bucks getting it into top condition, just don't want to if not neccessary.
Thanks,
Bob

 

[Laddies]

Re: 200, 20hp shifting problem

The plastic rev. cam is the only one availibe and also has spines the join the upper and lower shift shafts so it is for certain

 

[Bob1957]

Re: 200, 20hp shifting problem

Thanks Laddies, on my way to get the part tommorrow.

 

[Bob1957]

Re: 200, 20hp shifting problem

Laddies, or anyone else, I decided not to tear into my motor until I bought the part and had a manual in my hand. Well I have both and cannot find anywhere in the manual that describes what is inviolved in replacing the cam. I originally thought it would just slide off the shaft, but after looking at the new one I noticed there are two small tabs that apparently keep the cam from sliding off of the shaft. It looks like I need to remove the driveshaft housing from the motor? Any help would be greatly appreciated.

Bob

 

[Laddies]

Re: 200, 20hp shifting problem

Bob, it's been along time but I think that I used to be able to pull the lower unit and then caps and snap rings out of the lower torque tube mounts then the 2 screws that hold the cam to the torque tube and cheat the assm. out. If that won't do it then you will have to remove the powerhead as an assm. then the upper shift shaft the top torque tube and replace the cam. Nice deal thank the wonderful engineering staff at Mercury Marine

 

[Bob1957]

Re: 200, 20hp shifting problem

I was looking at some exploded diagrams and I assume that the screws you mention are in the cam retainer? I will give it a shot after work tommorrow.
On another note I rechecked the shift mechanism in the lower unit by trying to shift into reverse with LU off the motor. Forward and neutral are easy, but reverse is very hard to get into. I am turning the driveshaft clockwise and at the same time trying to shift into reverse. I cannot get it to go with just the cam on the shaft, it takes a pair of pliers and considerable force to get it there, reverse does work though. I guess my concern is that the original cam may have gone bad because of a faulty repair (see beginning of thread) and don't want to lose this one also, especially if I can't cheat it out. Any thoughts on why reverse would be so difficult?

 

[Laddies]

Re: 200, 20hp shifting problem

Get a good paets breakdown at BAM Marine site. Reverse is a max. compression of the shift sring and can be tough, it's one of the things that you almost have to know what it feels like. I can't explain on the forum, sorry

 

[Bob1957]

Re: 200, 20hp shifting problem

Well Laddie I gotta tell you that if you were able to cheat that retainer out of there AND get it back together you were not a mechanic, you were a magician. I'm going to wait until Saturday when I have more time and go the long route. Thanks for all the help, and patience. I consider myself to be a pretty talented mechanic and learned a long time ago that it pays to gather lots of info. before heading into unchartered territory. I'll let you know how I make out.

With much appreciation,
Bob

 

[Bob1957]

Re: 200, 20hp shifting problem, Finally fixed!!!

Re: 200, 20hp shifting problem, Finally fixed!!!

Sure a lot of work to replace a $6 part, but reverse now works and I know a whole lot more about my motor now. I do now believe that even if you can cheat the cam retainer out, it would probably be about the same amount of time and a lot less frustration to just pull the motor apart and do it the right way. Upon getting the old cam out, I inspected it and found the splines on one end completely shredded, obviously the reason that reverse would work for a short time and then fail again. Anyone facing this repair can feel free to contact me for a walkthrough of the process. Much gratitude to Laddies for helping me out with this one. Time to head out to the lake and get a handle on my WOT rpms and prop setup.

Smiling in Pa.,
Bob

 

[james33]

Re: 200, 20hp shifting problem

Hey guys...sorry to change the topic but i own the exact same motor and seem to be running into many problems....about two or three years ago my boat with the '74 mer 20 Hp on it sank. it was only submerged for a few hours and upon retrieval i was able to get the motor to start up with ease. since then i havent used the boat and the motor has developed problems....my first problem is that the impellar wont "Pee". I recently installed a new impellar and seals but came out with no luck. the motor will not circulate water. my second problem is that the motor will not advance to full throttle... I was using the motor (without water circulation for one weekend, for only about two or three minutes at a time and the next weekend when i went to try it the motor would only give me half throttle. I have checked the linkage and made sure the gas tank valve was open...Any suggestions would be greatly apreciated seeing as i would really like to use this new motor on my new hydrostream voodoo mini this summer.....

P.S this motor uses a standard Mercontrol remote system.