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MXU115 16x16 intermittent loss of 3rd and 4th.
OldIHMech posted a topic in Technical IH TalkHoping someone might have some info that could help make sense of the following problem. MXU115, 16x16 transmission problem. Started as an intermittent problem, but then got more prolific, and now almost guaranteed to happen daily. At first start for the day, or after standing for a few hours or more since the previous use- There is no drive in gears 3,4,7,8,11,12,15,16 (3rd and 4th ratios in each sector). Gears 1,2,5,6,9,10,13,14 have full drive power (1st and 2nd ratios in each sector). At first start, if the problem is evident, the tractor can be left idling in a non-operating gear and it will jump into drive after 2 to 3 minutes with all missing gears having returned, OR, it can be driven in the workable gears for 1 to 2 minutes and then all missing gears will return. Early diagnosis- The ADIC instrument panel upper screen had been unreadable (black-out) for a couple of years, so unable to retrieve codes, check configs, and re-calibrate via dash and jumper plug. Operator type trans calibration was available only. Dealer used laptop to load update software, re-configure, and re-calibrate all. Naturally, the problem was not present on the day the tractor was taken to the dealer, and did not re-occur until a couple of days after return to farm. A new ADIC panel was ordered from overseas, the tractor remained in use with regular re-occurrences of problem. The new ADIC panel was fitted, two HA errors appeared immediately on connection- 14091- Road speed sensor 12+. 14101- Water-in-fuel sensor circuit. A new road speed sensor was fitted. (But later found that it was not necessary. Case-IH’s Knowledge Base Article KA00000178/1000598 states that code 14091 is also used to register an error when a new panel is fitted to a 16x16 tractor as the new substituted part number panels are configured for a 24x24 transmission at manufacture instead of 16x16 as in the previous part number ). A new Water-in-fuel sensor was fitted. The new panel was configured to the tractor build, and all functions re-calibrated. The tractor returned to work, all functions working normally. The problem re-occurred intermittently as before, without any errors displaying, or registering in HA or DB. Later diagnosis- When the problem IS NOT present- The C1,C2,C3,C4 regulated pressures are all to spec (250psi). The Lube SUPPLY pressure is 2 Bar in F or R. The C1/C2 lube pressure is less than 0.5Bar, in all clutch pedal positions. The C3/C4 lube pressure is 2Bar in all clutch pedal positions. When the problem IS present- In 3rd or 4th ratios- The C1 pressure is very low, 110psi. The C3 or C4 pressures are very low, 160psi. The lube pressures are low as above. And In 1st and 2nd ratios- The C2 pressure is correct, 250psi. The C3 or C4 pressure are both correct, 250psi. The lube pressures are OK as above. Swapping the C1/C2 connections when the problem IS present. That is, the C1 harness connected to the C2 solenoid, and the C2 harness connected to the C1 solenoid- The 3rd and 4th ratios are now in the 2nd and 1st ratio shift indicator positions, but still have no drive and low pressures. The C1 pressure is 110psi. The C3 or C4 pressures are both 160psi. And The 1st and 2nd ratios are now in the 4th and 3rd ratio shift indicator positions, but still have full drive and correct pressures. The C2 pressure is 250psi. The C3 or C4 pressures are both 250psi. This would indicate that- As the low pressure remained with C1 and did not transfer to C2, then the software, calibration, controller, harness, and connectors, are not at fault. And As the C3 and C4 solenoid/valves supply full pressure while used in 1st and 2nd ratios, then they are not at fault. The possible causes?- Maybe the C1 solenoid/valve is intermittently faulty, and when faulty is dumping enough of the regulated flow available to also drop the regulated pressure of the C3 and C4 solenoid/valves when either are in use with the C1 solenoid/valve (3rd and 4th ratios). OR Maybe there is an excessive leak in the C1 circuit, and when leaking is dumping enough of the regulated flow available to also drop the regulated pressure of the C3 and C4 solenoid/valves when either are in use with the C1 solenoid/valve (3rd and 4th ratios). But, unlikely that such a large internal leaks could be intermittent. OR Maybe the transmission lubrication shuttle valve (combining valve) is jamming in a “clutch pedal feathering” position which combines the regulated flow with the lube flow for extra clutch plate cooling, which would dump regulated flow continuously, but, if that were the case, it would be expected to occur intermittently in all 4 ratios. Further tests- The C1 solenoid/valve was swapped-over with C2. The C3 solenoid/valve was swapped-over with C4. Outcome- No difference whatsoever. Next step- The transmission control valve assembly was removed. Air pressure was applied to the C1 clutch pressure pipe. The air pressure did not build-up, air could be heard escaping in the forward most gearbox section (C1/C2 clutch section). No clutch piston movement was heard. Air pressure was applied to the C2 clutch pressure pipe port. The air pressure did build-up, almost no air could be heard escaping in the forward gearbox section. Clutch piston movement was heard clearly. Air pressure was applied to the C3 and then C4 clutch jump tubes with same results as the C2 air test. The dilemma- There is definitely a huge leak in the C1 clutch circuit. But how could such a leak only occur during the first couple of minutes after start-up, especially considering the type of slip rings and piston seals that are used? Is there excess end-float in a component that allows slip rings to dump oil until it rattles back into the correct position after a couple of minutes of running perhaps? Where to next- Put the tractor back to work until winter time, and then remove the C1/C2 clutch assembly for inspection. But in the meantime it would be good to know if anybody has seen this problem, and if so, what parts were required. If the parts are ridiculously priced, or no longer available, then I would be more inclined not to split the tractor, and just to continue-on as we have by waiting for a couple of minutes before moving-off after first start-up each day.