Merc 850 shifting problem

[Wingedwheel]

I have a '73 model 85 hp with a problem shifting into reverse. When I first got the outboard it had this problem, but I adjusted the linkage and it cleared up. Now it has started doing it again and will shift fine if I go out and run the engine for a few minutes, but will only ratchet when cold. Any thoughts?

 

[Chris1956]

Re: Merc 850 shifting problem

That motor should ratchet when it is in forward only. Reverse will allow the prop to turn 1/4 turn in each direction.

Shift cable adjustment is easy. Put motor in nuetral. Remove shift cable from clamp. Move cable to and fro to make sure shifter is centered in neutral. Adjust barrel nut to fit clamp.

 

[Wingedwheel]

Re: Merc 850 shifting problem

Thanks for the tip, but I guess I should have said it makes a ratchet noise trying to shift in reverse

 

[sschefer]

Re: Merc 850 shifting problem

Thanks for the tip, but I guess I should have said it makes a ratchet noise trying to shift in reverse

You explained it well in the first post. Since this is a returning problem and the linkage is a direct contact cam style linkage the problem is most likely with the travel of the clutch. If you keep adjusting the linkage sooner or later you'll have no neutral or forward.

This could be caused by water in the L/U or it may just be worn out. You might be able to stave off a clutch replacement if you change your l/u lube and make sure you use a good quality 80/90w hypoid gear oil. Before you refill it and after you've drained it, with both upper and lower plugs removed, put about a 1/2 pint of Mineral Spirits in it and shake it around. Then drain it and blow some air through it to dry it out. When you refill it, fill it from the bottom until the lube comes out the upper fill hole, then plug the upper hole followed by the lower.

Some L/U's have a vent, fill and drain plug. I've learned to use the drain as the fill point and watch for fluid to run out the fill hole. Plugging the drain and filling from the fill hole means you fill to the bottom of the vent hole which leaves litte or no room for expansion and can blow L/U seals, make clutch dogs slip and cause early ratcheting during throttle backs.

 

[Wingedwheel]

Re: Merc 850 shifting problem

OK, There was water in the LU. I had just changed it not long ago so that tells me the seals need to be replaced. I replaced the outer when I got the engine, but as I'm replacing the impellor over the winter I'll do a complete seal change-out. Thanks for the tips

 

[Wingedwheel]

Re: Merc 850 shifting problem

UPDATE! I disassembled the lower unit and discovered the shift cam and cam follower were worn. Parts are ordered and I'll reassemble as soon as they arrive. I also made my own retaining nut removal tool. I'll post photo's of it soon as it saved my almost $100 by making it myself.

 

[egclassic]

Re: Merc 850 shifting problem

I have the same motor you have, and the same problem. Today I finally replaced the clutch dog and it seems to have fixed the problem. Won't be sure until I put the boat in the river Sunday. It would appear to shift OK on muffs or in a barrel in the driveway, but as soon as I'd put the ***** end in the water, I couldn't even get it off the trailer.

 

[Wingedwheel]

Re: Merc 850 shifting problem

egclassic. Unless the thing pops out of gear, the chances are your clutch dog is OK. Look for rounded over edges on the contact splines. I mic'ed the new cam follower and compared it to the old and found it was worn about 10thou.
Add that to the worn groove in the shift cam and I can see what was causing my problem. I'm all back together and firing it up this morn to see if everything is OK.

 

[egclassic]

Re: Merc 850 shifting problem

Well, had mine out today, still not shifting to reverse just sorta grinds.
Interested to see how yours is doing.

 

[Wingedwheel]

Re: Merc 850 shifting problem

Alright....Still having the problem. I've eliminated the cable and noticed the shift block was in the farthest rear position and still having problems. I'm down to the shift-shaft coupling as I looked up into it and can see the splines are almost worn out. Hard to believe the small amount of "slop" could cause this. I ordered the part and will update when done with this replacement. What a frustrating ordeal, but I'm determined and have eliminated just about everything else. Still, a small fix to enjoy my boat.....

 

[egclassic]

Re: Merc 850 shifting problem

What a frustrating ordeal, but I'm determined and have eliminated just about everything else

I hear ya! I am so frustrated, I'm thinking about selling the motor (for parts)and taking the 40HP motor my dad offered me!
After I replaced the clutch dog, it shifted so good in the test barrel, but as soon as I backed it into the river, grinding!(or ratcheting as you call it)

 

[JGra]

Re: Merc 850 shifting problem

I got an 80 HP 3 Cyl doing the same thing. As soon as you put it in reverse and without giving any throttle it just starts making a racheting noise. Was told my clutch dog was bad but now I wont if thats what it is. Will be watching this thread.

 

[egclassic]

Re: Merc 850 shifting problem

Winged,
Can you please post the part# for the shift shaft coupling? If that solves your issue, I will have to try that as well.
BTW, how much freeplay (up & down) does your shift mechanism at the power head have? I took a long screwdriver and pushed on it and it springs up and down about a 1/4"-3/8". Just wondering if this is normal.

 

[egclassic]

Re: Merc 850 shifting problem

Tried mine again today in the test barrel, after pulling the lower unit and checking my shaft coupler(which looked fine).
I shifted into reverse and it engages. As I increase the throttle, it dis-engages and makes the ratcheting sound. It seems better since I have replaced the clutch dog, before I could not hardly give it any throttle, but of course it's not right. This leads me to believe it has to be something in the lower unit itself not "holding" it in gear. Maybe the reverse gear needs replaced? another $200-300!!

 

[Wingedwheel]

Re: Merc 850 shifting problem

EG, Try $360 for that reverse gear. if you take the lower unit apart you might take a look at the cam follower. Mine was pretty worn, but it still stayed in gear. Once my coupler comes in I'll try and post pics of the difference in the splines. Does your shift block next to the power-head have any play left to move in reverse? if you have room it might be a cable adjustment. I have no more adjustment which leads me to the coupler. The splines look pretty worn and I'm thinking it has too much slop to fully engage the reverse gear. Normally the clutch-dog being worn causes the problem your describing, but if you replaced that and the gears were meshing fine you have to start working back-wards. I'd suspect the follower.

 

[egclassic]

Re: Merc 850 shifting problem

Try $360 for that reverse gear

nah, I've already found it alot cheaper online, several places. Just don't want to spend the cash if my existing gear is good.
My shift block has no play in reverse, like you, I have already eliminated the cable. My shaft coupler is in good shape, all splines clear.

 

[mike1245]

Re: Merc 850 shifting problem

where are you guys located at im in shreveport la and have a 1974 merc 850 that i will take 150$ for the whole thing it has good compression and is only missing the dist rotor and stator i need rid of this

 

[Wingedwheel]

Re: Merc 850 shifting problem

Sorry Mike, I'm in MI. Part shipped today, lets see what happens when it comes in.

 

[Wingedwheel]

Re: Merc 850 shifting problem

OK My part came in and when I pulled the old one off I noticed that the splines were worn almost flat which allowed for slippage in spring-loaded reverse, but was fine in spring-assisted forward. Installed new coupler and she shifted like new!YEA I'm out on the lake this eve for sure. I hope this has helped someone else with the same problem.

 

[egclassic]

Re: Merc 850 shifting problem

Not in my case. I decided to rebuild my lower unit. Found that reverse gear for $189, new.
Glad to see one of us had an easy fix!
I have to wonder what caused your shift coupler to wear in the first place, sounds like theres some other issue, like somethings binding up. That linkage should just turn in sync, so either your upper or lower shift shaft seems to be hanging.