This problem in John Deere 7810 started last May pulling a 4 row strip team. The hydraulic oil overheating alarm has tripped. We changed the filters and there was no change. We changed the sensors and there was no change. We took it to the dealership and they rebuilt the SCV couplers without any changes. We went back to the dealership and they rebuilt the SCV control valves without any changes.
The mechanic came to the field and said the fan clutch was weak. He changed it and the engine ran cooler, but the hydraulic oil was still hot. We finish the planting without finding the problem. This summer all the tractor did was run the rotary mower smoothly. Yesterday I put the stands and at two hours the alarm went off. The transmission is a quad range and it was working on B 4. I let it cool until the alarm went off and I shifted to C 3 and it ran at the same speed at 1600 RPMs with no problem. Shift to C 2 and ran at 1950 RPMs with no problem.
I switched back to B 4 and in 20 minutes the alarm went off. It was immediately switched to C 2 with the alarm still flashing and within two minutes the alarm went off and did not reheat. We pull the planter at B 3. The next thing the dealer wants to do is rebuild the transmission for $ 8000.00. Any opinions out there of what the problem could be. The dealer seems to be fixing the possible causes without really knowing what the problem is.
I appreciate all the responses. Now I understand better how the transmission works. The air pump is new to me, but now I can ask the dealer about that. I don’t want to let them do a $ 8,000 transmission rebuild if they don’t have to.
the air pump is definitely a possibility, we had a JD 7810 power shift that was overheating the hydraulics when I was going down the road a couple of years ago. if I remember correctly we had part of the air pump that came out of the drain plug or screen when we drained the oil and checked the screen. we took the transmission out and checked it instead of trying to replace the pump with the transmission in place.
The most likely cause if the oil is really hot was correctly indicated by Mr. 430wlpg. The air pump within the transmission’s John Deere 7810 PQ module normally builds pressure to transfer oil from the front of the transmission back to the rear differential compartment. At higher highway and planetary speeds, the extra oil in the PQ module is being sprayed by moving parts, creating drag, friction, and lots of heat. If the problem happens pretty quickly at highway speeds, I bet your air pump inside the transmission needs attention.
If it’s a problem with the hydraulic system, why is it only overheating in the B range? It overheated 4 times on the 10-mile drive to the dealer’s shop last year. He also ran probably 75 hours during the summer on the mower and that was in the B range, but not on full throttle with no issues. The dealership did diagnostics on it as there was a pile of prints in the cab when I picked it up. It pulls and shifts well so it’s hard to believe it’s in the transmission unless there is somewhere for a high pressure leak only when in the B range.
I assume you have a 16 or 20 speed Power Quad transmission. You say it only does it in the “B” range. What power shift gear are you in? When you run in the “C” range, what power shift gear are you in?
The reason I ask this question is this. The A, B, C, D and o / E are all mechanical ranges. They do not affect the hydraulic system in any way. Now Power shift part 1-4 is hydraulically operated. So if the transmission only overheats in range “B”, does it overheat in all speed range selections?So if it does it in B4 then running in C2 and it doesn’t then the problem would seem to be in hydraulic shift 4. So it would need to be running in C4 to check.
You also say that the warning light goes off.Is the oil really overheated or is it just the light / sensor saying it’s overheated?You could have an electrical problem instead of a hydraulic one.