I have a 4650 Powershift that has lost all drive functions and Hydraulics. The screen is clean, filters changed. Transmission oil pump system pressure is 40 psi, no lube pressure. Removed transmission oil pump to inspect, pump is in good condition, all gaskets replaced, pressure regulating valve, and filter relief valve are clean, springs are intact. Reinstalled pump and clutch valve still low system pressure. Am I missing something or any suggestions? Thanks in advance.
- Thread starter 88 Diesel
- Start date
I am with Tim on this one. If it happened almost instantly, I would lean toward the torsional dampner disk in the back of the flywheel failing. If so that is not a terrible fix.
This is not the greatest diagnostic but if you remove the starter and try to smell what the clutch housing smells like (yes using ALL our senses here), and it smell like burnt brake or clutch lining it may point to the failure.
This is not the greatest diagnostic but if you remove the starter and try to smell what the clutch housing smells like (yes using ALL our senses here), and it smell like burnt brake or clutch lining it may point to the failure.
Tx Jim
Well-known Member
- Location
- Coyote Flats, Texas
I'm probably wrong but I was thinking 50 & 55 series PS trans didn't have a torsional damper clutch similar to 20,30 & 40 series.
I'm still thinking about your problem....It seems that you have lost transmission pump flow some how,,and it sure points to the pump with what you have told us,,and I'm wondering if you opened up the pump when you inspected it??,,If the pump is indeed good then a pressure loss is taking place near the pump, and it must be a big one....If a clutch would have failed it would result in traction loss, but not in all the speeds....so I am sorta putting that on the back burner for now and thinking how the charge pressure has dropped out ??? And how it happened all at once?? Still thinking on it...
Thanks for the reply. I did break the pump down, the housing and gears look good and keyway is in place. I have been studying the flow diagrams in the operations & test manual to try and understand where the internal leak could be taking place. I did disconnect the transmission and shift through each gear to watch the system pressure, no major change on the pressure reading with each gear change. I do have an old pump out of a 4455 that sheared off the keyway and damaged the drive gear, I could try and piece the two pumps together just to rule out the pump.
If the old pump sheared the key it won't be of much good to you,,and if the pump that you are using has a good looking housing and gear it "should" be okay.. Check and make sure the cones are still in the trans oil filter housings,,I have seen them stick to an old filter and be discarded,, then there is nothing to hold the filter tight,,then the filter spins till the rubber washer on the end of the filter tears loose plugging a port where it can,,just another loose idea...when you find the problem it will be something silly and easily over looked...It's best to check all that you can think of before the split,,but a split is looking to be next,, and if/when you split don't forget the 2 pipes on the right side of the clutch housing, they need pulled out first...
ajdeereman
Member
4650 does not have a torsional damper on them the C1 C2 is in the flywheel. I have had a couple do this same thing and they were caused from broken bolts, heads broke off that hold the clutch pack together under the cab, allowing the clutch pack to separate slightly causing a massive leak and major damage.
Yes I had a 4050 blow the heads of the hi/low pack, but they didn't loose all the speeds,,and yes you had better get it to where you can split it and be prepared to lift the cab too. I backed a 4960 into a bay a few years ago and after the first split I seen where I had to lift the cab,, had to bump it back together and hog it around,,Darn it...I'll not let that happen again...
I do have the tractor ready to split and lift the cab, I am first going to check the filters as you suggested. If the main pack broke would the drive functions deteriorate slowly like what happened to this tractor? The op & test manual also suggested a packing failure between the clutch housing and transmission housing.
Yes some of these failures could act like yours is acting. A split and start looking process is next, just look closely as you go,,it should show up clearly, and it must be a big leak to kill the steering too.. and you know about the 2 pipes on the right side that need pulled first?
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