Put on an older, used LU on my '93 140hp v4 looper, fine on muffs and in the water in forward at idle, but then clunked loud and hard about every 2 seconds at forward slow, and about every half second with a little more throttle. Didn't do it in reverse though.
Seemed like the dogs hopping so I adjusted the control linkage to put more pressure on the shifter and it stopped clunking until about quarter throttle. Adjusted on some more pressure and got it to hold under 3/4 thottle, until the boat came out of the hole and the rpm's climbed up, then it clunked about every 3 seconds. I only let it happen a couple times each test before shutting down.
By that time, it was adjusted so far for forward that it started clunking when in reverse, so I pulled the boat back to the shop to check the gear oil for metal and/or water.
Oil looks pretty good but there is a little metal dust and it was clean, new oil when I started.
Anything I should check or adjust before I tear it down again?
The full story includes that this LU came with a one piece shaft that was ~1/2" shorter than my old 2 piece shaft, so I bought a new lower shaft and OMC shim gauge and shimmed it to the OMC manual specs, but without the jig, having read on another forum that it could be done that way if you were careful. I measured it to be a loose .004", so went with .005", to err on the long side, this unit having a little wear on the gears (although nothing visible on the dogs).
I also swapped in my old shift shaft, and set that carefully per the specs, although w/o the special tool.
The fact that pressure on the control linkage helped is confusing, I would have thought that the detents in the shift shaft would hold the gears in position.
It occurred to me that maybe this was a LU from a lower HP motor and although the internals look identical to the eye, maybe there's something just a little different about older LU's, the dogs have a slight angle to their mating faces or the detent spring is a little weaker or the upper shift rod lever had more throw, or something that would make it unable to perform with the 140's increased HP.
Any ideas what to look for when I tear it down again?
Sorry for the long post, tried to keep it short but also include pertinent info. Thanks for looking.
Seemed like the dogs hopping so I adjusted the control linkage to put more pressure on the shifter and it stopped clunking until about quarter throttle. Adjusted on some more pressure and got it to hold under 3/4 thottle, until the boat came out of the hole and the rpm's climbed up, then it clunked about every 3 seconds. I only let it happen a couple times each test before shutting down.
By that time, it was adjusted so far for forward that it started clunking when in reverse, so I pulled the boat back to the shop to check the gear oil for metal and/or water.
Oil looks pretty good but there is a little metal dust and it was clean, new oil when I started.
Anything I should check or adjust before I tear it down again?
The full story includes that this LU came with a one piece shaft that was ~1/2" shorter than my old 2 piece shaft, so I bought a new lower shaft and OMC shim gauge and shimmed it to the OMC manual specs, but without the jig, having read on another forum that it could be done that way if you were careful. I measured it to be a loose .004", so went with .005", to err on the long side, this unit having a little wear on the gears (although nothing visible on the dogs).
I also swapped in my old shift shaft, and set that carefully per the specs, although w/o the special tool.
The fact that pressure on the control linkage helped is confusing, I would have thought that the detents in the shift shaft would hold the gears in position.
It occurred to me that maybe this was a LU from a lower HP motor and although the internals look identical to the eye, maybe there's something just a little different about older LU's, the dogs have a slight angle to their mating faces or the detent spring is a little weaker or the upper shift rod lever had more throw, or something that would make it unable to perform with the 140's increased HP.
Any ideas what to look for when I tear it down again?
Sorry for the long post, tried to keep it short but also include pertinent info. Thanks for looking.
