Power Beyond SCV "Burp" Noise

[rwinter]

I bought a used Deere 4720 eHydro with Backhoe and abt 350 hours. After some backhoe work, we took it off (routing the hydraulics back into the tractor with the loop) and did some bushhogging and loader work. After about 30 hours of additional work, I noticed a rattling, sort of burping noise in the back every minute or two. I saw that the power beyond OUT hose fitting would jump and rattle on the metal backing plate as if a surge of air or something was going through the system. The hydraulic-transmission reservoir is full.

As someone new to tractors, I am not sure what to think....I saw one post about a O-ring, but I am not sure where they mean or how to check this. I have checked to make sure the fitting is secure--I have removed and reset a few times.

Thanks for any advice you might have.

 

[jenkinsph]

I think I would check the hydraulic pump suction lines on the (curb) side of the tractor. These tubing lines and connections may be intraining air into the system, make sure these connections are all tight. Once the oil passes through the pump it is under high pressure and can't let any air in, so I would say the suction lines are the most likely culprit.


Steve

 

[kennyd]

Just to expand what Steve said, look in the tank while it's running to ensure the fluid in foaming-if it is you need to fix the leak ASAP or you WILL destroy your hydraulic pump.

 

[rwinter]

Steve---can you tell me what the "curb" side means?

thanks

 

[jenkinsph]

Steve---can you tell me what the "curb" side means?

thanks

sitting in the tractor seat it would be your right side or the passenger side of a vehicle.


To further elaborate on the prior post the larger hydraulic line that comes into the hyd. pump and branches to the two sections of the pump is the one to look for. The two smaller lines leaving the pump are the pressure lines, one for power steering and one for the tractor hydraulics.


Steve

 

[rwinter]

My tractor came with a FEL and backhoe, so it has a lot of hydraulics, in addition to two lines out the back I have yet to use, and some in front for a grapple bucket. From what I can see, there is a bank of 6 somewhat smaller lines coming from one section of the pump, and one slightly bigger one that sems to go forward to near the engine on the tractor....is it the latter where you think could be the problem? I did try to tighten it, but it seemed tight....or could it be the 6 slightly smaller lines?

Thanks

 

[jenkinsph]

Here is a picture of the hydraulic pump on the 4520 notice the larger line on the top that feeds both sections of the pump this is the line in question. Further see the hose clamps on this line to the left of the pump? Trace this line and its connections all the way back.


Steve

 

[rwinter]

So that is the hydraulic pump....I had no idea. Thanks so much.

Steve, I cannot believe how kind you were to take the trouble to take a picture and send it back. People like you, and there are a lot on tractorbynet, are the best! Thanks again.

 

[jenkinsph]

You are welcome, I went ahead and bought a camera this week and thought I would try to post some pics anyway.


steve

 

[rwinter]

Steve---I checked the tubing and it seems secure, like no air can come in. I assume the suction side is the large top tube, which goes to the filter and then on to the transmission sump, apparently.

What is the rubber sleeve in the top tube for which is secured by hose clamps? Do I need to redo these joints?

Think it could be an air leak in the filter? It seems secure and there is no apparent oil leakage anywhere.

The only thing that is curious is that the burp/vibration only occurs on one fitting--the power beyond fitting. I would think that if the problem was on the suction side of the hydraulic pump, that other valves would do the same, wouldn't they? Of course a lot of the fittings have no flow through, they are dead ends

thanks for any ideas you can give me