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What's in
the shop?
John Deere 2440 PTO Problems.
1-888-530-4554
Toll-Free U.S. & Canada
Owosso Tractor Parts www.owossotractorparts.com
Customer: “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
bobscorner@owossotractorparts.com
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