3020 PTO Pistons

IAtractorKid · Mar 16, 2023

Late model 3020 synchro. Hydraulic leak at
clutch housing after using PTO. Suspect
PTO pistons... They were supposedly
replaced last spring with the clutch
before we bought the tractor. Maybe that
was a lie or something was done
incorrectly. Have parts ordered, but
have a couple questions:

Can these be replaced without splitting?

Is there a specific length or torque spec
for the bolts with springs on them?

Can this be done without draining
hydraulic fluid?

Thanks for the help!

IAtractorKid · Mar 16, 2023

matthies · Mar 16, 2023

Have to split, don't need to drain the system, just replace the pistons again along with the oring/backup rings, AND NOW THE HOUSING THE PISTONS GO INTO. Can get through A&I cheaper than JD. The bolts with springs are flush with the back of the housing or less as they are up against the trans housing. Can just run them in until they stop(don't force) and lock the nut.

wore out · Mar 16, 2023

There isn't so much as a drop of oil at either piston, unless you've wiped them off it MAY be something else that is leaking.

COULD be the seal between the two shafts, (29), and/or the seal at the back of shaft (31) that requires a split between the clutch housing and the transmission to change, or even the ''packing'' that seals the oil pressure passage between the clutch housing and the PTO clutch apply pistons.

IAtractorKid · Mar 16, 2023

It had been cleaned off in the pic. I'll
double check before I split.

It does not look like that shaft support
is available anywhere that I can see...
AR41210. Guess worst case I can hone the
holes and make custom dowels to fit...but
how tight of a fit would one want?

wore out · Mar 16, 2023

I checked the Tech Manual for dowel and bore diameter and did NOT find any info.

Seems to me though, unless the bores are HORRIBLY worn it should have sealed at least for a while with new O-rings, backup rings and dowels.

Wonder if the backup rings were installed ''successfully'' and in the correct (outer) position?

I'd suspect an error there more than a worn housing.

WTW · Mar 16, 2023

A lesson learned from working on these common problems / leaks the last 44+ years. I had a 4320 (Probably 30 years ago) that these same PTO clutch control pistons would leak after replacement of pistons, O-rings, backup rings and piston housing. PTO clutch finger height was rechecked and set correctly which also can cause the piston seals to wear fast if finger height is not right / consistent. Even went was far to have new piston housing machined adding a second set of groove to piston housing bores to double up O-ring seals to just see them leak again in a few months. Long story short, leak was product of was a pulsating pressure from the main hydraulic pump that was spiking the supply pressure to PTO control valve and these pistons. Fixed the worn out hydraulic pump and problem solved. If you install a pressure gauge in and SCV outlet and the gauge needle is a blur the piston pump is just beating the ling snot out of your seals. Lesson learned.

mtb34 · Mar 16, 2023

wow thats a pretty picture ... did you clean it up?

mine looks like a rusted mess.

IAtractorKid · Mar 17, 2023

With seal 29 and/or 31 you mentioned,
would it leak all the time? I was thinking
the PTO pistons as it only leaks when
using the PTO.

matthies · Mar 17, 2023

WTW is right about the pulsating, make sure the valve is adjusted properly. The spool of the valve needs to bottom out in the housing and stay there as the lever is over centered to engage. I was the last guy to fix a 4320, after 5 other techs tried to fix the problem at the dealer I worked at. Was pulsating also, but adjustment fixed this one.

3020 PTO Pistons

IAtractorKid

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IAtractorKid

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matthies

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wore out

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IAtractorKid

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wore out

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WTW

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mtb34

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IAtractorKid

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matthies

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