Hydraulic System seems overpressured?

   / Hydraulic System seems overpressured? #1  

kevintGA

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Aug 9, 2022
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Tractor
New Holland TC40DA
I have a New Holland TC40DA. I recently took it in for a 500 hour service and a PTO issue. The PTO was still strong, but would have to spin up, so I had the clutch rebuilt. When I got the tractor back I did about 30 minutes worth of work with the backhoe, and then the next weekend took the tractor and bush hog and cleared some light brush for my brother in law. The tractor is equipped with a front end loader and I used it to flatten some dirt and remove brush and saw that the right FEL cylinder was leaking at a pretty good rate. I checked and the seal was coming out in tiny shreds. I checked the left cylinder and saw the same tiny shreds, but not and bad and it hadn't started leaking. I quit working and loaded the tractor up. When I got the tractor home I detached the FEL, and noticed that my HST filter was leaking. I ended up losing about a gallon and a half of hydraulic fluid. To complicate matters, I checked my oil, and the oil is over full. The tractor was running fine but judging by the dip stick it is significantly over filled. I'm not familiar with the way my hydraulic system works and am somewhat concerned that the oil system may be full of something other than oil. For what its worth, the substance on the dip stick appears and smells like oil.

Does anyone have any ideas on what could have caused these issues? I plan to remove and replace the hydraulic filter, remove the excess oil and then test to see if the oil system overfills again or the hydraulic system experiences other problems. This tractor should have a hydraulic overpressure device shouldnt it?
 
   / Hydraulic System seems overpressured? #2  
Your hydraulic pump is probably driven by gearing off the crankshaft. If the seal fails it will dump hydraulic fluid into the crankcase. There should be a hydraulic over pressure relief valve. It is adjustable. Your dealer can check and adjust the pressure if needed. If you have a gauge it's usually a simple adjustment.
 
   / Hydraulic System seems overpressured?
  • Thread Starter
#3  
Your hydraulic pump is probably driven by gearing off the crankshaft. If the seal fails it will dump hydraulic fluid into the crankcase. There should be a hydraulic over pressure relief valve. It is adjustable. Your dealer can check and adjust the pressure if needed. If you have a gauge it's usually a simple adjustment.
Thank you, I suspected that it could be hydraulic fluid in the oil. To repair the PTO clutch the rops and entire rear of the tractor had to be removed. Am I wrong to think this issue is a result of the work I just had done?
 
   / Hydraulic System seems overpressured? #4  
The failure of a seal in the pump is probably not due to work you had done as they would have no reason to remove or work on the pump. It is probably possible over pressure could cause oil to bypass the pump seal - I don't know it's construction. In any case I would get that pressure checked and adjusted. It's frequently just a spring pushing a ball into a seat with a screw adding pressure to the spring. Adjustment is normally pretty straightforward.
 
   / Hydraulic System seems overpressured? #5  
But why would the relieve pressure adjustment have changed??
 
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   / Hydraulic System seems overpressured?
  • Thread Starter
#6  
That’s my question too, and not only why would it have changed so much but why would I have hydraulic fluid shooting out from around my HST filter, two cylinders, and the pressure relief valve never let off. I don’t have a pressure gauge to check the pressure with but am headed down to pick up the rebuilt FRL cylinders and will ask if they have one.
 
   / Hydraulic System seems overpressured?
  • Thread Starter
#7  
So, I've changed my HST filter and the filter I had on hand was a different size than the one the mechanic used. My filter is correct, the one he used was a slightly larger diameter. I drained the oil down to the correct level and took pictures of the hydraulic and oil levels. A hydraulic shop in town is going to let me use a pressure gauge to check the hydraulic pressure. Im going to check the levels tomorrow and see if they've changed, if not run the tractor and check the pressure and then recheck the levels. The oil I removed didnt smell like hydraulic fluid and didnt appear to be mixed with anything that would cause it to streak or look milky.
 
   / Hydraulic System seems overpressured?
  • Thread Starter
#8  
Another update. It’s been 24 hours, checked and the fluids were at the same levels as yesterday. Ran the tractor a minute, no leaks at the HST filter, checked fluids and at the same level. So next I drove it around for 5 minutes, checked again and no leaks same fluid levels. I hope my issues are over…at the moment it seems like the mechanic put on the wrong filter and overfilled the oil.
 
   / Hydraulic System seems overpressured? #9  
Did you ever put a pressure gauge on it to see what it was making?
 
   / Hydraulic System seems overpressured?
  • Thread Starter
#10  
Did you ever put a pressure gauge on it to see what it was making?
I haven’t yet. I decided to try it without it since I didn’t haven’t it yet, and had no issues. I do intend to test it before running it longer though
 
 
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