Anyone good with fixing Mercury Motors? Trim problem!

  • Chris R
    54474
    Posts: 46
    #2057104

    Hey everyone, just looking for a little help to get pointed in the right direction for a fix on my 2016 Mercury 150 4Stroke(not ProXS).

    Last weekend we were fishing our walleye series championship tournament and when we launched for day 1 the trim seemed to “jam” and had the motor stuck in the up position after removing the transom saver.  Working the trim up and down with the switch a couple times finally released the motor so we launched and soon found that we were without full trim operation.  We had no “down-pressure” and the motor would actually kick up if throttling in reverse when maneuvering out of the marina.  

    We were able to make it to our spot safely as the weather conditions allowed us to run with the trim in the full-down position with no issues.  I did find that trim would lift the motor to about 1/3 height but then once off the switch, the motor would settle back down to the full-down position.  Back in the marina at the end of the day, I was able to trim the motor up enough to make sure the skeg didn’t hit the ground when pulling the boat out of the water, but was not able to get it to lift high enough to put the transom saver back under it, so we lifted it manually to do so.  We did notice that near the top of the trim range(with the motor in the up position and the transom bracket lock engaged, the trim motor would run when you pressed the switch, but would take a few seconds before anything happened.  In this position, after holding the switch for a few seconds, the motor would operate “up” but then seemed to “bounce” past the upper limit.  There was still no “down” operation, though the trim motor would run.  We checked the fluid and it appeared to be full and there were times when the hydraulic cylinder would hold pressure and keep the motor up, but once a button was pressed or you put any pressure on the motor it would settle back down to the full-down position.  

    Additional details: No visible hydraulic fluid leaks from any trim component, trim pump motor runs(evident by sound) in both directions, can hear pressure build in cylinder when manually lifting motor, this is the first time having any sort of issue with this motor.  Mounted on a 2016 Ranger Angler 1880, fished each of 3 days prior with no issues at all, no warning signs.

    Anyone have any advice as to which component might be the culprit?  I haven’t removed the trim assembly from the boat yet, but plan on doing so this weekend.  I’m hoping it’s a serviceable part that would resolve the issue, rather than replacing the entire assembly.

    Thanks in advance!!

    KPE
    River Falls, WI
    Posts: 1717
    #2057108

    Sounds like it might be low on fluid, despite no visible leaks. Can you try topping it off with hydraulic fluid?

    Chris R
    54474
    Posts: 46
    #2057132

    Sounds like it might be low on fluid, despite no visible leaks. Can you try topping it off with hydraulic fluid?

    That was the first thing we checked when we got off the water and back to the hotel. With the motor full up there was a small trail of fluid that started running out when we removed the cap, so it should’ve been full, but we topped it off with some fresh fluid anyway, still no change in operation.

    Iowaboy1
    Posts: 3829
    #2057176

    Sounds to me like either the piston sealing ring is worn out or one of the check valves isn’t holding.
    Pretty easy to overhaul if the bore isn’t scored.

    Chris R
    54474
    Posts: 46
    #2058680

    So I finally had time to tear into the trim unit and found what I hoping least to find. I was hopeful that there was a valve or something that failed, but was quickly discouraged when I drained the fluid on the bench and found a significant amount of glitter in the fluid. Still I removed and checked all valves, filters and the pump, only to find more glitter and some slightly work springs in the check valves. Finally I removed the cap for the cylinder and found this severely worn ring and ridge in the upper third of the cylinder. Certainly explains why it stuck in the “up” position. I can’t explain why it’s worn like that, but my best guess would be that this is the position the motor rides at with the transom saver when trailering.

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