# Hydraulic Pump cavitating on my 5105



## woodbutcher (May 5, 2009)

I have a JD 5105 I bought new in 02. It has a whopping 117 hours on it. One day while bushhogging I caught a rock and it broke the site glass on the back of the tractor where you check the hydraulic fluid level. It sat out for a week or so and water (a small amount) leaked into the system due to the crack. I fixed the glass and ran the tractor for a bit and noticed the fluid got milky. I drained the entire system to evacuate the milky fluid. I pulled the filter and everything I could find that had fluid in it. I put new JD fluid in it and ran it. The milky fluid is gone but the hydraulic pump is making a groaning sound. Im told that noise is called cavitating. Any clue why it would do this? The fluid is completely clean.


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## Live Oak (Dec 22, 2003)

Welcome to Tractor Forum woodbutcher! Did you pull, inspect, and clean the suction screen for the hyd. pump? The contaminated fluid may have clogged up the suction screen and this could be the cause of the cavitation. 

The bad news is that you must drain the trans./hyd. fluid to check this. Do not run the tractor any more than is absolutely required until you fix this issue. Running more will just damage the pump more. The pump may already be damaged to the point of requiring a rebuild but before we proclaim gloom and doom, let's check the suction screen first. 

Good luck and be sure to follow up and post what you find.


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## woodbutcher (May 5, 2009)

Which screen? It runs in my mind that there is one back at the hydr filter and one at the pump. Is that correct? Im pretty sure I did clean it out and found no debris. I took everything apart to get as much water out as I could. Would running the pump with water in the fluid cause it to cavitate like that and remain cavitating even after new hydr fluid was put in? I probably ran it for a few hours before I realized the fluid was getting milky. It's especially loud on cold days. Changing the fluid is getting expensive. Maybe there's a place online where i can find an exploded diagram of the hydro system. Oh man...now Im rambling. Sheesh!


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## Live Oak (Dec 22, 2003)

I may be mistaken but isn't there a suction or pickup screen at the bottom of the transmission case where the oil is drawn from?


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## woodbutcher (May 5, 2009)

I dont know. 

I'll see if I can find an exploded view of the hyro system and see if I can find the screen. Hey...thanks for the help!


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## Live Oak (Dec 22, 2003)

I checked on the JD Parts website and there does not appear to be a suction screen on the line feeding the pump from the transmission as far as I can tell. Usually there is some kind of hyd. pump suction line pickup screen. 

You might try removing the suction line at the pump and have a look to see if any contamination is lodged in the pump.

Another possibility is that contaminated oil may have caused a relief valve to stick open. 

At this point, I am out of suggestions. Have you put a pressure guage on the pump yet?


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## woodbutcher (May 5, 2009)

I pulled the line off the top of the pump to take a peek inside the pump. It looked extremely clean from what I could see. I did not put a pressure gauge on it yet. Also on a side note the steering is really choppy now. It's quite possible something is lodged in it...but not sure what it could be. I evacuated the entire system and drained the fluid twice. It's completely possible that the tractor had something in it from the factory. I bought a Yamaha ATV a year or so ago and after about 25 miles it started to cut out. I took it back to the dealer, they opened up the carb and found a bug in the carb...so it's possible something is stuck in it somewhere. I hate the thoughts of draining the fluid again. I did blow air through the system to try to get as much of the contaminated fluid out. Maybe I messed something up in the process. I wonder if there is a bleeder valve on it somewhere. I thought it was a self bleeding system.


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## Live Oak (Dec 22, 2003)

The system is self bleeding but requires running all of the hydraulic circuits full extension to displace any air.


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