John Deere 2440
PTO Problems.
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Owosso Tractor Parts
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Custom
er: “PTO shaft
turns when there is no load but quits when the bailer is hooked up” He
said it was not a gradual thing but rather it quit all of the sudden. Of
course it quits when he is bailing hay. Why would it break any
other time, after all its hay time.
PTO problems can be a little tricky to figure out sometimes and the problem is not always what you first suspect. Usually when we get a tractor in for repair we look for the obvious things first. Well, this one took a little figuring out. In most situations when fixing a tractor you can decide if you want to be a Parts Replacer or find the problem and fix it correctly. You will get a lot more satisfaction diagnosing the problem and fixing only what needs to be fixed. You know there is a saying “If it’s not broke, don’t fix it” and how true that is when it comes to tractor repair. When repairing any tractor it’s best to visit a service manual. The, I&T service manuals are a great source of information. So, we check the PTO operating pressure in the top of the shift cover and come up with a whopping 40 Lbs. It’s supposed to be 140 to 160 Lbs of hydraulic pressure. So next the service manual says to check out the main hydraulic pump and sure enough it was low and the pump seemed to be running when it should not be. John Deere piston pumps have a standby pressure that when the pump is not needed it holds out the pistons inside the pump away from the drive shaft. When you hit the lever of anything using hydraulic pressure such as a remote valve lever, the hitch or the steering wheel, the pistons return to the pump drive shaft and again start pumping oil. If the standby pressure is not high enough, the pump will try to run making it noisy and erratic. I have personally overhauled a couple of hundred of these pumps so it helps when diagnosing hydraulic problems. So out comes the pressure gauge (3000 psi) and a quick check at the remote coupler tells us it only has 1900 Lbs of main pump pressure. That was an easy fix. We just adjusted the stroke control valve on the bottom of the hydraulic pump and we had the necessary 2,280 Lbs of hydraulic pressure and the pump quit running when it’s NOT supposed to run. So, back to the PTO gauge (a 500 Lb gauge) we go and again only 40 lbs of pressure. Next we added a couple of thin washers to the PTO regulator in the back side of the shift cover and again only 40 lbs of oil pressure. By setting the main hydraulic pump pressure to MFG specs, it must be in the PTO circuit for sure. Maybe your thinking it’s the PTO clutches that are bad. Wrong. The final conclusion was to remove the top shifter in this Independent PTO setup. Pressure test, (with air) the PTO pressure tube with a blow gun. You know that sound when you blow into a straw in a cup of soda, well that’s what we got in the bottom of the transmission housing (that test was not in the service book). But first we checked the PTO brake tube and it was fine. No leaks. Next was the determination that we had either a cracked supply tube or blown “O” ring(s). We split the tractor at the clutch and transmission housing and there in plain site, at the bottom of the transmission housing was not a split PTO pressure tube but one that was completely broken in half at the bracket that supports it. We went ahead and pulled the PTO clutch pack apart (since we were already there) and the disc’s looked brand new. No harm done to them at all. Now we have to wait for parts from our friendly John Deere dealer and it will go back together as good as new. Keep an open mind whenever working on your tractors and discuss your problem with friends who know tractors and be sure not to forget the invaluable service manual. They may not give you the exact answer you are looking for but they are a big help in diagnosing any problems. Or you can simply be a Parts Replacer. It’s your money and time.
Thank you for visiting.
Sincerely
Bob Baumgras
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