I have John Deere 7220 transmission oil overheating problem. My John Deere has been out pressure checked all hyds, pressures are correct, all filters have been changed twice, cut open, no metal in filters, tractor does not labor as if pump is being stroked, could oil cooler be the issue
Transmission/hydraulic oil overheating can occur for different reasons and for different reasons. There is a separate DTAC solution for each cause. It is important to use the correct tractor model, transmission type, hydraulic system type and application in each case to determine which DTAC solution to use.
Two significantly different hydraulic systems may be involved. The 6020 and 7020 small frame tractors use a PFC (pressure and flow compensation) or closed center system. This system has two pumps (charge pump and main pump). The charge pump continuously supplies oil to the main pump. The main pump will only supply oil on demand when it is necessary for the high pressure hydraulic function.
To assist the technician and shorten diagnostic time, we have listed the following four steps in order of frequency, as the most common problems and their respective causes of hydraulic oil overheating.
1. Hydraulic pump exceeds the minimum pressure with no hydraulic components engaged.
- High pressure leak to load sense circuit.
- Incorrect power beyond spacer block adjustment w/3rd SCV installed.
2. LTC (Low Temperature Circuit) not opening at the correct temperature.
- Refer to solution 61629.
3. PowerQuad Transmission – Loss of vacuum at the transmission air pump.
- Broken spring at air pump piston.
4. Loss of coolant flow at the LTC circuit.
- Internal or external leakage in radiator -refer to solution 65650.