4320 vs 4020

I didn't like the lack of torque rise on the 46 and 43's... the 43's I thought were worse in that regard.

there is a slight problem in the rearends-- a pin can fall out inside that will cause the gears to lock up...( happend to both of those tractors I drove)

the 4020's were peppier to me.. and I loved that 4620 it was awsome for a 10yr old to run that thing ( we had one of the very first 4620's)

I have experienced the loss of hydraulics with the clutch pushed on my 4020. There is a Service Information about it on my web page linked below. In those its due to loss of a check valve deep in the transmission and the cure is converting an elbow to a check valve where its easy to get at. In later 4020, there was a check valve in a T at the hydraulic oil reservoir up front according to a service bulletin I have. I don't know if that covered 4320, since I've not had any interest in the 4320. One other service bulletin of that era suggests there might be a leak from the high pressure circuit to cause that rapid loss of hydraulic with the clutch pushed. I know on another forum last week that someone found a bad O-ring in some assembly in the transmission case that was the cause of his pressure leak in a late 4020. That was harder to find and to get to than adding the check valve to the elbow which would not have fixed his problem.

With the SI number from my web page you should be able to get a print out of it (just text, no pictures) from a JD parts computer to see if it covers that vintage of 4320. A really good old time JD shop supervisor might remember service informations or bulletins on the problem in the 4320.

Gerald J.

• Fixing 4020 hydraulics

The fundamental problem is that the oil cooler and a reservoir up front hold more than a couple gallons of oil. If the check valve in the early 4020 in the transmission or near the reservoir of the late 4020 leaks the front pump runs out of oil quickly. That's the function of making the elbow into a check valve to replace one that's hard to get to in the depths of the tranmission. But if there's a high pressure leak bypassing oil from the output of the main pump it will use up that reserve fast too. I know putting the check valve in the elbow on my '68 4020 did fix the loss of hydraulic with the clutch pushed in. More than once I've let it set for months, pushed in the clutch, started it, and raised the loader before letting the clutch out. Working in a basement hole, I'd seat the loader bucket in the dirt on th side, and push in the clutch shift gears while I was turning the steering and rocking the bucket to break the bite loose and beginning to lift before letting the clutch out in reverse to back away. Busier than a one armed paper hanger, but the hydraulics kept up.

Gerald J.