Mercury trolling motor

My trolling motor is not working properly. It is about a 1984 Mercury Trolling motor. Not spinning as fast as it should at high speed. I have taken it apart and checked the brushes and wiring, everything good. Brass bushings are in good shape and so are the seals. Is the magnet supposed to be as strong as it is? With the motor not in the magnets and with the end caps on the motor it spins freely. Smokes a little at the brush cap end when running and gets hot. Battery is fully charged, voltages does drop to 8 volts when I hit the switch to run motor. The motor will slow down and speed up with the potetionometer (don't know how to spell that) but it just seems to be binding up somewhere. Any thoughts? Thanks Todd.

Re: Mercury trolling motor

Yes the magnet is, When I had my shop the 70lb's could break your finger if you got it in the way putting one back together, You should not have that much of a drop. This is hard to explain but if you look at the metal portion that the brushes ride against they are separate pieces of brass or copper or whatever connected to windings. In between them should be a clean space. What happens over the years is this gets filled with brush deposits and dirt, whatever. That space needs to be cleaned out so there is no electrical connection between the plates so that they are acting independent of each other. Make sure the brush springs are still good. Look for hot spots in the wiring under load. Try a different battery and see if the drop is still that much. Blow the armature with compressed air and try to get all the old brush dust out of there. It is conductive.

I am sure one of the armchairs is going to tell you to have your battery load tested so I won't bother

Re: Mercury trolling motor

I understand completely. There was some brush dust in between the copper plates. I will give that a try. I did try a different battery before, that was the first thing I tried before I took the motor apart. Thanks for the reply, I should have thought about that to begin with, but I was thinking of other things besides the simplest.. Thanks again.

Re: Mercury trolling motor

Thanks kahuna123, that was what the problem was with the trolling motor. Running good now. Thanks again...

Re: Mercury trolling motor

No problem good to know I could help.