Hello,
I have a 1994 JD 450G Dozer (farm machine) - direct drive machine (793 991) with an odd transmission problem.
I was doing some light clearing of brush hardly loading the machine at all. I had just started so the machine had run less than five
minutes so it didn't really have much time to heat up. (Engine and hydraulic levels/operation are good.)
I was going up an incline of probably about 25 degrees and I notice this medium frequency whine start. About a minute after that I got
the STOP alarm light and the "Transmission Oil Temp/Pressure" light on.
I stopped the machine and checked the transmission fluid level, found it low and was surprised to find that it took about five GALLONS
(out of 27 total capacity) to get it back on the stick. Have had no signs of leakage. (Bought the machine about a year ago and had not
had a problem with it in that time. The tranny had been fully rebuilt.)
I topped it off with Hygard and the STOP light went away, but the whine was there only very faint. The following morning it started fine
and I went back to work, but not 3-5 minutes after I began, on flat ground, I started getting the same Stop/Temp/Pressure alarm, but only
intermittently cutting in and out. I again stopped the machine and started looking again.
What I see in detail:
Switch of bulb check shows all alarm lights working.
The transmission oil filter restriction light is not lighting up when the problem occurs. Transmission fluid level is slightly above the
mark and has not leaked off.
The machine moves fine. When I dig in the transmission does not slip. Shifting is timely and smooth, it sits still in neutral, steering
clutches operate smoothly, both tracks pull evenly/straight and brakes operate smoothly with reasonable pedal pressure.
The only indication of trouble is that light whining sound plus the stop & transmission press/temp alarm cutting in and out.
After reading everything I could get my hands on the only external thing I could find wrong related to the transmission is that the
filler cap had the tension screw backed off and air pressure couldn't build up in the tranny case. Tightened that and it seals fine. But
that is likely unrelated.
My first thought is an intermittent/marginal pressure problem related to the transmission pump that is piggy backed to the hydraulic
pump. My problem comes in that the op/service manuals show disassembly/reassembly, but don't give any testing procedure to measure the
pump pressure/etc as a diagnostic procedure. (other than "see your dealer") Sure would be nice to know what the tranny output pressure
range should be and where to plug in a test gauge.
I am about two hours drive from any major city with a Deere dozer equipment dealer (and I have heard that these folks are not as heavily
interested in the Deere mystique of keeping older machines running as they used to. Giving me the impression that costs/help would be
harder to get or way too expensive for the small farm guy that is not going drop a couple hundred grand on a new earth mover.)
I am looking to see if anyone here has run into this or similar issue and might pass along some advice about how to find the real
troubleshooting procedure that a Deere Tech would use to see if I have a bad pump or something further down the line. Or even a reasoned
guess about it.
All comments welcome and appreciated!
Bruce
Exurbs, TN
I have a 1994 JD 450G Dozer (farm machine) - direct drive machine (793 991) with an odd transmission problem.
I was doing some light clearing of brush hardly loading the machine at all. I had just started so the machine had run less than five
minutes so it didn't really have much time to heat up. (Engine and hydraulic levels/operation are good.)
I was going up an incline of probably about 25 degrees and I notice this medium frequency whine start. About a minute after that I got
the STOP alarm light and the "Transmission Oil Temp/Pressure" light on.
I stopped the machine and checked the transmission fluid level, found it low and was surprised to find that it took about five GALLONS
(out of 27 total capacity) to get it back on the stick. Have had no signs of leakage. (Bought the machine about a year ago and had not
had a problem with it in that time. The tranny had been fully rebuilt.)
I topped it off with Hygard and the STOP light went away, but the whine was there only very faint. The following morning it started fine
and I went back to work, but not 3-5 minutes after I began, on flat ground, I started getting the same Stop/Temp/Pressure alarm, but only
intermittently cutting in and out. I again stopped the machine and started looking again.
What I see in detail:
Switch of bulb check shows all alarm lights working.
The transmission oil filter restriction light is not lighting up when the problem occurs. Transmission fluid level is slightly above the
mark and has not leaked off.
The machine moves fine. When I dig in the transmission does not slip. Shifting is timely and smooth, it sits still in neutral, steering
clutches operate smoothly, both tracks pull evenly/straight and brakes operate smoothly with reasonable pedal pressure.
The only indication of trouble is that light whining sound plus the stop & transmission press/temp alarm cutting in and out.
After reading everything I could get my hands on the only external thing I could find wrong related to the transmission is that the
filler cap had the tension screw backed off and air pressure couldn't build up in the tranny case. Tightened that and it seals fine. But
that is likely unrelated.
My first thought is an intermittent/marginal pressure problem related to the transmission pump that is piggy backed to the hydraulic
pump. My problem comes in that the op/service manuals show disassembly/reassembly, but don't give any testing procedure to measure the
pump pressure/etc as a diagnostic procedure. (other than "see your dealer") Sure would be nice to know what the tranny output pressure
range should be and where to plug in a test gauge.
I am about two hours drive from any major city with a Deere dozer equipment dealer (and I have heard that these folks are not as heavily
interested in the Deere mystique of keeping older machines running as they used to. Giving me the impression that costs/help would be
harder to get or way too expensive for the small farm guy that is not going drop a couple hundred grand on a new earth mover.)
I am looking to see if anyone here has run into this or similar issue and might pass along some advice about how to find the real
troubleshooting procedure that a Deere Tech would use to see if I have a bad pump or something further down the line. Or even a reasoned
guess about it.
All comments welcome and appreciated!
Bruce
Exurbs, TN