Hard Shifting 2000 Merc 60 HP

[chris in houston]

60 hp 2000 Tracker Merc (3 cyl 2 cycle): hard to shift N to F and worse from N to R. When I had LU out to replace impeller, I put pliers on shift shaft and found it impossible to turn from F to N (turning CCW) even while hand turning driveshaft CW. I would get to the end of the F range as I turned CCW, then could not turn further. The shifter handle/cables seem to be smooth when disconnected from motor. Thus, I think it's binding in the LU.

Any thoughts on cause and how to cure my hard shifting would be much appreciated. Thanks!

 

[Texasmark]

Re: Hard Shifting 2000 Merc 60 HP

Never went into your engine but have had Mercs for many years. Their shifter is operated by a splined shaft that turns a cam with 3 detents of different depths mounted in the front of the lower unit at the front end of the propshaft. There is a spring loaded pin that follows this cam and this pin moves the shifter shuttle (riding on/around the propshaft) from the forward physical position engaging the R gear to the mid position where the F and R gears are not engaged, to the aft position where the F gear is engaged with the drive gear on the driveshaft.

A lower unit that has been contaminated by water/corrosion could keep this spring loaded, ball bearing filled, hollow, "cam follower" pin from moving back and forth in the propshaft.

My best guess since you had it down to the lower unit only and it was hard to shift....or you have a frozen upper bearing supporting the shaft...just under the upper shift shaft seal (immediately under the water pump lower plate). Removing the prop and the rear seal/carrier bearing assy will allow you to pull the prop shaft and this pin assy will come with it. With them out, you can feel the shift shaft for smoothness and ease of operation which will/should point to the pin/spring/ball bearing assy as the culprit. A thorough cleansing of it should put you back in service with a new set of shaft seals/carrier bearing and oil fill-drain screw seals and fresh oil.

Mark

 

[chris in houston]

Re: Hard Shifting 2000 Merc 60 HP

Mark, thanks for the reply. Upper bearing OK, since when I had LU off the shift shaft turned easy until I got to the N shift point.

So I take it the "spring loaded, ball bearing filled, hollow cam-following pin" is th elikely culprit. Is this a big job? What tools will I need - a special puller? And do the seal and bearings need replaced or just reinstalled?

Also, as a lazy person, I'm always looking for the easy way out. Is it possible I could drain the LU oil, but in gasoline or kerosene, shake it best I can, then drain and refill with lube? I know, I know.....I said I was lazy.

 

[Texasmark]

Re: Hard Shifting 2000 Merc 60 HP

Don't know the answer to the lazy question, necessarily. A solvent poured into the LU and back and forth movement of the shift shaft could free things up, but one has to wonder what the solvent would do to the seals in the lower unit. If they are made of neoprene they may survive a solvent like naphtha (I think Home Depot carries it in a gallon can in their paint dept).

You could go to Parker Seals www, look under the material and check out what it resists. I'm going to bet they are made of that material unless they upgraded seals to a newer silicon based formula; either way you should be good to go and if you take out a seal, no biggie as you'd have to pull the prop shaft assy. anyway and replace the seals in the process if you initially dismantled it.

I'd keep it in the vertical (more or less) position to keep the solvent from getting to the top where the upper shaft seals are located.You could go to a farm store and get a 30 cc syringe (a big one, don't need any needle) like would be used on cattle and inject naphtha through the upper lube hole (vent hole) and drain it out through the lower (fill hole) hole in the lower unit when finished. A 48 hr soaking wouldn't hurt. When finished, I'd let it drain overnight to get it all out then refill with fresh oil.

As far as trouble, depends on how your lower unit comes apart. As mentioned, either you have a 2 screw system (screws are just above and below the propshaft on the rear of the LU) or a spanner nut system which would require a spanner wrench if you don't build your own. The spanner nut fits into the threaded housing from the rear. I noticed traffic on here within the last two days to the fact that ebay or craig's list may have some for sale....comment said $50 area.

If you don't have the 2 screws showing, pull the prop off and look inside the rear of the housing. Removing the nut, or the 2 screws, will allow you to grasp the propshaft and pull it out. The cam follower will come out with it as will everything else you need to look at except for the shift shaft and the cam on the bottom end of it. The F gear and bearings will still be in the front of the housing and can be lifted out if desired (just sitting there) or left where they are. Be careful with the follower as inside is a spring and may be as many as 3 ball bearings (used as tensioners).

While out you should replace the large diameter Oring sealing the bearing carrier to the housing and the rear propshaft seal.

What did I miss?

Mark

 

[chris in houston]

Re: Hard Shifting 2000 Merc 60 HP

Great advice and explanations, Texasmark! Thank you very much.

I will try the lazy approach, but will be prepared for dissassembly. I can't help from thinking that something is worn between the cam,pin and shifter shuttle that is causing it to "catch" and bind. In which case, cleaning won't help.

I'll give an update after I dig into it.

 

[chris in houston]

Re: Hard Shifting 2000 Merc 60 HP

Update: I drained the LU, refilled with gasoline, started it to "stir it up", then drained and flushed with more gas. Then filled with lube, started and drained again. Finally refilled with lube second time. Seems to shift better on muffs in driveway. Will try out in lake today.

One curious note: I expected to use a quart or more, but I bet it didn't take 1/2 a quart. Is that expected, or could there be a bunch of crud in there taking up space? The gasoline flush turned clear, so I think I got most of the old stuff out.

PS: I know you're all cringing at the thought of gasoline in the LU to clean it. I'll be watching seals and oil for any leakage, but so far so good.

 

[Texasmark]

Re: Hard Shifting 2000 Merc 60 HP

I don't have a problem with gasoline. That's what I use in similar circumstances.....I just didn't want to tell you to use it. Grin

As far as seals, it wasn't in there long enough to hurt them...my opinion, but probably true.

As far as lube, that housing is pretty full of gears and shafts and all. Don't be surprised about the quantity.

On crud buildup, I'd doubt it. Just put it in the bottom hole and wait till it comes out the top hole(s) nice and clear and button her up (My 90 has 2 vents; first engine I ever had with 2. The center fills first, cap it and keep filling till the front one vents).

Maybe you got her fixed. If not, you haven't lost a lot and you surely don't have to worry about whether or not you got it all back together correctly.

Before you decide it didn't work, might give it some time to "loosen up".

Mark

 

[chris in houston]

Re: Hard Shifting 2000 Merc 60 HP

My son took the boat out today and reported shifting better. Unless things are different when I try it out, I'm considering this problem solved as well as possible without tearing apart the LU and replacing parts. That will be the next step if necessary. Thank you TexMark for all the help! Very informative and helped me isolate the issue. This forum is great!

 

[Texasmark]

Re: Hard Shifting 2000 Merc 60 HP

Glad it seems to be working for you.

Mark