Trans case lock seem not to work anymore

[Pete Judd]

A few months ago It worked great when I had to cross one of my creeks, today, I had one wheel slipping and stomped the pedal, and it did not engage. I have not gone to the manual yet, and it was getting dark, the pedal stayed down and had to pull it up with my heel. Any thoughts? This is on a 186D

[Powerlinefixer]

Check the linkage and make sure nothing is sticky.

The diff lock on my 155d did the same thing so I sprayed some rust cutter on the pivots and worked them back and forth. The rear pivot that goes into the case was really sticky. I removed the linkage and had to use a rubber mallet and lots of lube to free it up. Works perfect now.

[California]

Here's what my YM186D needed. This could be your problem too.

The end of the DiffLock lever inside the transmission has a rollpin through it. When you press the pedal, that rollpin tries to climb the slope of a v-notch on the shifter fork. This slides the fork along its shaft.

When I bought my YM186D the difflock didn't work. I assumed tearing down the differential to fix it would be complex so before I brought the tractor home I dropped it off at a former Yanmar importer/dealer for the repair. He said if the problem is limited to replacing the fork then this is simple, just remove the pto and top cover.

He found the problem was just wear on the fork and offered to order an expensive new fork, or simply weld on material to fill the gap in this photo then grind/polish it back to the original contour. I had him weld it. (Real old-school tractor repair. ) It works fine.

I agree with the suggestion to check the linkage first. But if you find this is your problem, the repair won't be difficult.