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Old 01-01-2018, 02:05 PM
aero320 aero320 is offline
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Join Date: Jun 2008
Posts: 500
Default Reparing my Minn Kota Terrova Trolling Motor

I have a 2012 24V 80 lb. thrust Minn Kota Terrova trolling motor with iPilot that started making some motor noise recently. I wanted to share with the group what I discovered when repairing the trolling motor myself.

I was slow trolling one afternoon and the trolling motor started making noise. I could actually feed vibration in the hull of the boat. Used the motor the rest of the trip.

Still have my previous trolling motor in the attic (Minn Koto Powerdrive 24v/80/Autopilot/co-pilot) so I got it down, put new batteries in the remote, plugged it into the boat, and it worked fine. Took quick trip to the lake for a lake test before I started working on the Terrova.

Wrote down the serial number and located the parts diagram on the Minn Kota website. Called Minn Kota and talked to a service person, very helpful. He said to check the prop and the prop shaft to see if it was bent. Not likely the problem since it started making noise in open water.

He suggested putting a new seal kit and see if that cured the problem. In the worst case scenario, you can buy a complete new motor with US2 and 60" shaft for less than $400. I knew, I could make that repair if necessary.

We talked about the possibility of having water in the motor and he indicated that even if there is some water, you can dry it out, replace the seals and it might be all right. Excessive water will cause the armature to short out and it will destroy the main board in the upper part of the trolling motor. This board is about $225. Since my trolling motor would still run, I figured the armature was OK.

It was time to remove the prop, shear pin, and the two bolts than hold the motor together. First, there was no water in the motor. There may have been some condensation at one time but did not appear to cause a problem. Could not get the red and black wires loose from the Brush block. The armature looked fine.

They sell a Brush Block kit that contains a new brush block (with brushes) all of the orings and seals that you will need along with the front bearing and various washers that are required. The kit was about $45 and included both the Red and Black wires connected to the Bush Block. This must be a common problem.

The Kit did not include the thrust bearing that goes at the rear of the motor so I wanted to replace that also. Minn Kota sells a rear motor housing (Terrovas's have the skeg on the rear of the motor housing) for about $22 and it includes all of the seals and thrust bearing already installed. So all I needed to purchase was the rear housing and the Brush Kit. Of course I did purchase a few parts that turned out redundant (not a lot of $$$).

The wires at the top of the motor all have connectors and are easy to disconnect. A single bolt holds the top part of the motor to the shaft and removing the bolt allows you to remove the top housing. The locking collar bolt on my Terrova had gotten rusty do I decided to replace it while everything was taken apart.

There are four wires that run from the motor unit through the shaft to the top of the motor. The Red and Black power wires that attach to the Brush Plate mentioned before. The trolling motor has the US2 transducer, so a transducer cable runs through the shaft. There is also a small brown grounding wire that attached to one of the bolts that attaches the brush plate. These wires were used to try prevent depthfinder interference.

With all of the parts that I would need on hand (plus a few bonus parts) I called Minn Kota one more time to get some advice about assembling the motor then began the task. I worried most about getting the brushes pulled back when the armature was inserted but that turned out to be fairly easy.

You basically run the wires though the shaft. You will need enough slack in wires to move the rear housing back about the width of a finger so that you can insert a screwdriver and push the brushes back so the clear the commutator. Once that has been done, there is a shield or clip that slides in between the magnets on the top side to keep the wires clear of the armature. The clip actually slides in from the front to the motor. You will also need to adjust the slack on the transducer cable before you slide the clip in. Not really a problem either.

The armature installs from the front and the magnets are very strong and will pull the armature into the motor housing. Watch where your fingers are when you do this. The magnets center the armature from front to back. You will need to reach into the small gap that you left for the brush plate with a screw driver and push the brushes back so they clear the commutator. This will allow you to slide the rear motor housing against the main motor housing. There is an Oring that fits in between the housing just as there is in the front section.

Slide the nose cone onto the front of the motor housing and get everything aligned. The easiest way I found to the those long screws aligned correctly was to place the motor vertically resting on the nose cone. That means the the long screw would also be vertical. There are two bosses that stick up from the nose cones that have the threaded holes for the screws. You can "feel" when the screws are resting on these bosses and that will help you get the long screws started in the holes.

After connecting everything back on the top end, I took the trolling motor over to the boat and plugged it into power. Took the iPilot remote over to see if the motor would rotate. On a Terrova, depressing the deploy lever will allow the motor to operate and the directional motor to turn. Every thing seemed to work so I installed the trolling motor back on to the boat and did a lake test. Everything works and the motor is quiet again!

Having said all of that, here are some additional observations. First, I though $400 for a new motor and shaft was a good deal so in the worst case scenario, that was my maximum exposure (plus shipping). By the way, according to Minn Kota, when you purchase and Ulterra motor or Terrova motor, the shaft is included. I think they are glued together rather than threaded.

Also, I was thinking about "What else could go wrong in the future" that is mechanical, and discovered that the little box at top that rotates the shaft is available as a complete unit. From the looks of the parts diagram, there is a drive motor and lots of gears and sleeves. The replacement cost for the entire unit is about $110. I thought that was also a good deal.

It is New Years Day and I wanted to share this trolling motor experience with fishingTN. Now if it would just warm up a little!
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