John Deere 4640 No Hydraulic

[Brownbrothers]

My 4640 won't go forward or reverse the
power steering won't do anything the three
point wont go up. I have changed the
strainer the filter I have took the top
link off and took the plug out. I can't
get the shaft to slide but it terns when
it's running the transmission oil light is
staying on when running. I guess what my
question is what or were is the next thing
to check or do. It has a quad range
transmission

 

[wore out]

Even if the hex pump driveshaft is turning it could be stripped out inside the transmission pump gear.

It SHOULD pull out the back relatively easily for inspection.

 

[WTW]

I agree with last post. The hex shaft has stripped its flats in the transmission pump gear. That is why you cannot remove it because of the mismatch where hex is stripped in pump gear. It will still turn but, is not driving transmission pump which supplies your two speed, traction clutch and then supplies the main hydraulic pump with charge oil. There may be a reason pump shaft failed?? I have seen top transmission shaft fail the rear bearing which then caused the pump shaft to fail.

 

[Brownbrothers]

I finally was able to get the shaft out it was stripped. I put a new shaft in it. I run it for ten minutes everything was working and stopped put it in another gear and won't move the steering is working and three point is working what would be the best thing to try next this is the only john deere I have worked on.

 

[wore out]

(quoted from post at 15:00:06 12/03/23) I finally was able to get the shaft out it was stripped. I put a new shaft in it. I run it for ten minutes everything was working and stopped put it in another gear and won't move the steering is working and three point is working what would be the best thing to try next this is the only john deere I have worked on.

You have steering and brakes FOR NOW, as the transmission pump refilled the front pump charge circuit and oil cooler during the short time it worked, but the hydraulics will stop again as that oil leaks back ''to sump''.

Replace the transmission pump as the internal hex in the gear that is driven by the hex shaft is likely worn out.

Then, verify that the clutch operating pressure is in the normal range.

 

[Brownbrothers]

Do I half to split the tractor and take the
cab off or can you change the pump with the
cab on. I have a book on the way. I know
the rock shaft housing has to come off. I
was just wondering what the easiest way is.

 

[buickanddeere]

.

When in deep enough to replace the transmission pump . There are some 41+ year old seals that maybe worth replacing .

This post was edited by buickanddeere on 12/04/2023 at 08:23 pm.