Shifting Problems

1985 50HP 4cyl Mercury. SN: A133192

The motor will shift into forward, but not reverse. Checked the lower unit and found black peanut butter, with some metal shavings...especially on the magnet. Replaced fluid, no improvement (didn't think there would be).

How can I know if the shifter mechanism is working? I can see the shifter cable move the lever at the base of the engine compartment, but is there a certain amount of travel I am looking for?

It worked one day, then over the next few times it required harder or further shifts until it no longer worked at all. Kinda had to throw it hard into reverse to get it to work, and then it would clunk hard.

My best guess is that the gears are tore up. But my question is how do I know if the problem is the lower unit or the shifting mechanism?

And lastly, if the problem is the lower unit..is it best to replace or rebuild. I'll be doing the work myself, and I'm new to outboards, but handle car and other repairs adequately?

Thanks for your thoughts!

Re: Shifting Problems

That s/n comes up as a model:

1050625 MERCURY 1985 50

Parts listing:

http://www.crowleymarine.com/mercury-outboard/275.cfm

Have you tried disconnecting the shift cable at the engine and shifting the lever by hand?

With the cable disconnected shift the lever full forward and that will be FORWARD gear, shift full aft and that will be REVERSE, the middle is NEUTRAL. Mark the F/R positions and check the travel to these marks after the cable is re-connected. In each position, with the cable still disconnected, check the prop rotation for the following:

FWD prop will not turn CCW
NEU prop will turn freely CCW or CW
REV prop will not turn either direction

You don't have to force the prop, just light pressure to try and turn it. If everything works out, you can assume that you are shifting correctly. Re-connect the shift cable and move the boat controls to F and R (checking prop rotation in each position) and see how close you are to the marks you made previously. This should tell you if you need to adjust a cable.

With the metal contamination on the plug and your description of the shifting problem, it sounds more like the jaws of the clutch are rounded off on the R side. You can see the clutch under GEAR HOUSING (PROPELLER SHAFT), item 59 and it slides between F and R gears for gear selection.


The best service manual is Mercury P/N: 90-86135--5

http://cgi.ebay.com/ebaymotors/DEALER-MANUAL-MERCURY-MARINER-SERVICE-MANUAL-/140452275932

Here is a condensed version of the Clymer manual. Let the page load for 30/40 seconds.

http://web.ebscohost.com/serrc/pdf?...a255-313ccb1b1c20@sessionmgr113&vid=4&hid=113

Gerry