# Where is the filter bypass valve on a JD 540A?



## Virginia Farmer (Sep 5, 2013)

I have a JD 540A skidder which suddenly lost steering and blade function. I have had the machine for about a year now, when I first start it she will jump the steering to one side, after that it is fine for the rest of the day, well if she runs for a long time then hydraulic functions slow down, let it cool off for a bit and it is back to normal. I figured it was a pressure relief somewhere. Well the other day I shut it off, to fell a tree, started it back up and had no steering or blade function. She will shift into drive and reverse, but otherwise nothing. Of course it is way down in the woods, I removed the pressure relief valve and will tear it apart in the AM to see if there is an issue there. The book speaks of a filter bypass valve that dumps to the sump as well and for the life of me I can not figure out where that is. When I bump the starter hydraulic oil immediately comes out of the the line, and the pump appears to be a lot newer than the machine so I don't think that is the issue. Any ideas? Thanks


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## redprospector (Sep 5, 2013)

I've got a 440-b (different critter, I know). Speaking from experience, I'd just change the hydraulic filter where it sits. 
When blade and steering act up on mine, the filter is the culprit 9 times out of 10. 
I can't find my bypass either. 

Andy


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## northmanlogging (Sep 5, 2013)

I do not believe there is such a thing as a bypass on the deere... (thats guessing though) generally on my 440a loosing steering and blade function is a result of low hydraulic oil level I.E. air in the lines somewheres...

But I don't have the power shift, I got the psycho rage tranny...


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## redprospector (Sep 6, 2013)

Low fluid level can do it too, I just figured he had already pulled the stick.
I've got the syncro too, and it can do some strange stuff when that filter gets plugged.

Andy


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## northmanlogging (Sep 6, 2013)

7th gear 3/4 throttle, no brakes, chooglin through a narrow skid road... and all the sudden you can't turn left...


Could also be that you need to bleed the system, the bleeder is under the dash on the left side of the steering valve thing... it kinda small but looks allot like a brake bleeder.


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## treeslayer2003 (Sep 6, 2013)

a filter bypass is spossed to open and let fluid go around a plugged filter. if your tractor is full of fluid, it sounds to me like a blockage or pump problem.


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## Virginia Farmer (Sep 6, 2013)

Thanks guys, I changed the filter not all that long ago and she is full of fluid and it looks clean on the stick. I pulled the pressure relief valve off and will pull it apart per the book, figure it can't hurt. The book also mentioned a sump screen - any idea where that is?


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## treeslayer2003 (Sep 6, 2013)

Virginia Farmer said:


> Thanks guys, I changed the filter not all that long ago and she is full of fluid and it looks clean on the stick. I pulled the pressure relief valve off and will pull it apart per the book, figure it can't hurt. The book also mentioned a sump screen - any idea where that is?



if you have a powershift, it should be attached to the big plug on the bottom of the trans. I am not real familier with the A model tho.


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## redprospector (Sep 7, 2013)

Depends on what's in the bottom of the trans. 
Sometimes it doesn't take long to plug the filter.

Andy


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