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Discussion Starter #1
Hello
Can someone explain how the Charge Check Valve on a Sauer Danfoss 15 series U Type tranny works? I checked mine out and they both were pushed down. I took them out cleaned them but I had to manually push the pin up and down. Seems like the spring inside is not automatically pushing the pin up. Is the spring inside supposed to automatically push the pin up, or does pressure from the dydro supposed to push it?
They both seemed sticky and stuck.
It does not seem to come apart for repair or cleaning.
Thank you
 

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The pressure from the pump will push them up if they are stuck down.

Was something wrong with them to prompt the cleaning/desire to rebuild?
 

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Pek, A little over a year ago, the check valves on my 317 were sitting in a puddle of oil. Deere wanted $147 each so I looked around online. I found places that rebuilt them and places that sold new ones. I found LJ Fluid Power in Delton, MI. (269) 623-4150 that supplied 2 new valves for $140. A quick phone call, and 3 days later I had new valves installed! Bob
 

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Discussion Starter #4
Thank you for info and Thanks for asking
318 runs fine until it gets hot. Then it either starts off slow then speeds up and/or with the control rod all the way forward it still is not full speed or is difficult to go up small hills. The linkage does have very little play and I will tighten that up on the S shaped control rod. I found there is play at the top of the shock absorber #11, in the bracket #12, and the arm #23 where pin goes through, the hole got bigger.
Since I was messing with that I also decided to replace my disintegrating fuel lines and tranny fluid level site tube hoses, and pump filter.
But I thought I mind as well check the charge check valves and charge relief valves. I don't know enough about either to know if the are working properly, so I was just going to replace them. But they cost more that I expected.
I also thought it could be the charge pump too but lots of $$ for rebuild parts.
I'm kind of going through process of elimination.
 

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Pek, The check valve need to do 2 things: NOT leak, and pop up when the engine/hydro runs. With seat pan removed, start tractor, warm for 2-5 minutes, and shut down. Move free wheeling lever to depress valves and then raise up to "storage" position. Start tractor and watch valves, they should pop up...no need to move hydro Frd/Rev lever.

Charge relief valve is actually for your hydraulic control levers for moving attachments. A pressure gauge can be installed in a front hydraulic outlet. Moving your lever should give a reading, ~around(??)~ 900 psi I believe. If you've got that, your fine.

After repairing/replacing site tube asm, drain oil, replace filter, and refill oil. I'd recommend JD Hy-Guard or Lo Vis, depending on temps where you live. You may find that your slowing down when hot went away!

One more! While your replacing fuel line components, pull hoses from fuel tank. You should have a filter or screen on the end of the tubes...clean or replace. Bob
 

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Discussion Starter #6
Good advise
I found in tank fuel filter had a hole in it and the grommets where fuel lines enter tank were cracked and leaking..
replaced hydro fluid, filter and cleaned both check valves and replace it's o rings.
i will advise on status after start and bleed off air.
 

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Discussion Starter #7
Hello
Got her all put back together and gassed up. Started up ran great, then saw a second hydro leak at charge pump seal-lip.
Time to research how to replace that booger.
I will update
thank you
 
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