Having a problem with my D21-A5. I used it to do some gravel-moving on my neighbors driveway, which is a steep hill (50-80% grade). No noticeable problems. Parked the dozer. I cranked it up a couple days later, and there was a strange whining noise. I put it in 1st to go forward, and nothing happened. Sometimes it does this when its cold, but after waiting 30 seconds or so, I became concerned. It finally moved, but very hesitantly and intermittently. I got it to a good spot and checked all the fluid levels. Blade hydraulics were a little low but, everything else was fine. I spent some more time playing around with it and here's a synopsis of the symptoms:
1. Whining noise when in neutral, but goes away when in gear
2. Moves fairly well at low rpms, can even push a pile of dirt
3. Steers properly
4. Inching pedal and brake work properly
5. Works better in 2nd gear than 1st, regardless of direction
6. If moving at low rpms, and then transitioning to higher rpms, it loses drive at somepoint around 1/2-full throttle
7. The whining noise returns as rpms climb
Anybody got any ideas? I pull the directional and inching valve off the top of the transmission and inspected it, everything looks great. Not sure where to go next.
Thanks in advance.
Never saw any replies on this, but got the problem solved. Ended up being the cleanable (wire mesh) filter element. It was an easier fix than expected. With the top covers off, take the two 13mm bolts loose at the front bottom left of the transmission. Pop the cover off and catch the 8-15qts of 30wt that will come pouring out. The filter will likely wash out with the oil.
Once I got the filter out, it was covered with grit, grime, and what looked like old gasket material from something. I sprayed it down with PB Blaster, then Carb cleaner, then water hose, then PB Blaster, then Carb cleaner. Looked a lot better so I gave it a gentle rubbing with a wire brush, then repeated the spraying process a couple of times.
Assembly is the opposite of disassembly, but make sure you put the filter in with the open end facing out. If you don't, you'll have to get a really strong magnet and pull it back out (ask me how I know). Add a couple of quarts of oil, and then run it a little to circulate everything around before topping off.
Previously, when I put it in gear, it would hesitate from 5-15seconds before starting to move. After cleaning the filter, as soon as I put it in gear, it jumped forward, and is now moving more consistently and better than ever.
Also, if you are thinking about replacing the filter, get a price first. Local dealer quoted me somewhere around $300. Fortunately they were knowledgeable (and nice) enough to tell me it could be easily cleaned.