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76 4430 air in hydraulic oil

D

DManey

Member
I have a late model 76 4430 and I seem to have a lot of air in the hydraulic oil, more it runs the worse it gets. Just did load shaft and bushings, cleaned the suction screen and put new hy-guard in. Is there any other place tHan the trans pump for air to get into the oil? I'm thinking there is a o-ring or possibly something wrong with the pickup tube. Wanted to consult the experts before I take the rockshaft off.
Thanks
Derek
 

I seriously doubt removing rockshaft will reveal where air is entering hyd system. How long has hyd oil been foaming? How long have you operated tractor since cleaning sump screen?
 
Last year end of season it was getting worse. Seems to be affecting overall hydraulic function, especially once warm. Hydraulic oil shouldn't look like it's emulsified with water, except it's air.
 
(quoted from post at 20:17:44 05/04/18)
On 2nd thought it's possible that suction line on trans pump is not sealing
Click to expand...

I forgot to mention it's a quad range. So I just wanted to make sure there wasn't somewhere else it could be getting in other than the suction of the trans pump.
Thanks
Derek
 
This don't happen often,, what kind/brand of oil is in it?? I have seen some unknown brand oil show up here in tractors and some of it looks milky and foamy,,flush and put new oil in and it's okay.About the only place for it to actually suck some air would be the suction tube to the trans pump/0-ring,pump manifold area,,after that the oil is under pressure with no suction involved..I don't know your tractor history,,but I have seen the diff center pin come loose..work out a bit and ding the trans pump manifold a bit to make it leak...but "most" of the time when that happens it knocks the whole Darn pump off...
 
(quoted from post at 22:57:01 05/04/18) This don't happen often,, what kind/brand of oil is in it?? I have seen some unknown brand oil show up here in tractors and some of it looks milky and foamy,,flush and put new oil in and it's okay.About the only place for it to actually suck some air would be the suction tube to the trans pump/0-ring,pump manifold area,,after that the oil is under pressure with no suction involved..I don't know your tractor history,,but I have seen the diff center pin come loose..work out a bit and ding the trans pump manifold a bit to make it leak...but "most" of the time when that happens it knocks the whole Darn pump off...
Click to expand...

Thanks Tim, figured that would be the only spot. I bought the tractor a year and a half ago. I don't know the whole history either, but I did just buy hy-guard from John Deere to put back in it. The old stuff was kinda dark.
Thanks
Derek
 
(quoted from post at 00:57:54 05/05/18) Does the hydraulics seem to work okay..
Click to expand...

The longer I run the tractor the worse they get. Ive messed with stroke control valve, checked standby pressure checked the press on the transfer pump. Tran's pump pressure gets a little low when hot, but within spec in my jd service manual.
 
I'll start by saying that I have no experience with these tractors but a fair understanding of hyd. systems in general.

Barring any leaks between the charge / trans. pump & the pick-up screen are there any potential sources of high pressure leakage inside the transmission case that could be aerating the oil in the sump?

Not likely but just a thought.......
 
(quoted from post at 19:57:08 05/07/18) I'll start by saying that I have no experience with these tractors but a fair understanding of hyd. systems in general.

Barring any leaks between the charge / trans. pump & the pick-up screen are there any potential sources of high pressure leakage inside the transmission case that could be aerating the oil in the sump?

Not likely but just a thought.......
Click to expand...

I've done the hyd. pressure tests in the jd service manual, so far haven't found anything as far as a high pressure leak. I did switch it to hy-guard, just finishing up a couple things putting her back together, hope I can put some hours on it with the correct oil tomorrow. I have no clue what was in ithe prior to me buying, I did change hyd. filter when I changed the engine oil. The stuff I drained out was definitely a darker color than the new hy-guard.
 
Got the rockshaft off last night, found the clamp wasn't holding discharge pipe in the trans pump tight. I borrowed a video stick inspection camera and ran it in through the plug in the back, seen the oil spraying around the pipe. More throttle the spray got real bad. I'm ordering parts this morning.
Thanks for all the help guys.
Derek
 
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