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still stuck on hydro


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#1 BOLENSBOY60 ONLINE  

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Posted December 29, 2017 - 06:57 AM

still trying to diagnose the sunstrand implement relief pressure- changed /shimmed the valve- checked charge pressure- cannot get pressure over 150 when dead heading the lift cylinder- could a charge pump get weak?



#2 boyscout862 OFFLINE  

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Posted December 29, 2017 - 07:57 AM

Any pump can wear and get weak. HAve you check the pump output pressure? When I used to diagnose hydraulic problems I had to make up test rigs that included pipes, tees, valves and gauges. There is a manual in our Manual Section that talks about test proceedures and shows some of the test rigs. Good Luck, Rick

#3 chieffan ONLINE  

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Posted December 29, 2017 - 08:05 AM

Are you testing with the cylinder in the line?  Could be the cylinder seals are leaking and oil is flowing by them, thus low pressure.  Push the cylinder to end, loosen the line line at the cylinder output and apply pressure by way of the control valve.  If you have a spray of oil, your cylinder is bad. Makes a mess but short of removing the cylinder about the only way.

 

Can also put you gauge on the line going into the cylinder but that will make a mess also.



#4 BOLENSBOY60 ONLINE  

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Posted December 29, 2017 - 08:51 AM

thank you guys for your input- this all started because my power steering did not work - the fluid flows directly to the ps valve first- then out to the dash control valve then out back to the hydro- I did remove the control valve and replaced o rings to eliminate that- as another member noted- I deadhead my auxiliary hydraulics and still pressure only jumps up about 25 psi - I do have the test procedures for the sunstrand 15 inline - charge pump test is acceptable - I replaced the implement relief valve even added shims- almost seems that the charge pump is allowing fluid to partially pass by internally



#5 BOLENSBOY60 ONLINE  

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Posted January 02, 2018 - 06:34 AM

still no luck- should have mentioned- I do not have any history on this tractor- bought it non-running because it had the ps option- and I wanted to put a loader on it- anyway my drive works good- plenty power to the ground- I have good readings on charge pump pressure- but implement pressure is way low- when dead heading the lift cylinder it jumps to around 150 -then quickly drops back down to the 125- or so- checkd flow by removing the in- and back lines good flow but seems lack of pressure- Tudor has ben giving good advice eliminating possible causes and trying to diagnose- just trying to make sure as I would rather have a good direction before I remove the hydro

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#6 29 Chev ONLINE  

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Posted January 02, 2018 - 10:52 AM

You could try adding some Lucas oil additive for Automatic Transmissions to the fluid and see if that made the pressure any higher - might give you a better idea if the pressure is from an internal leak inside the pump - just a suggestion.  I also sent you a pm that has a link to a Sundstrand document in the Tech Tips section that may be of interest to you.


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#7 BOLENSBOY60 ONLINE  

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Posted January 02, 2018 - 03:44 PM

sounds like a good idea- may as well give it a try- will keep you posted


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