JOHN DEERE 8630 HYDRAULIC QUESTION

francis

Member
I had a problem last week with my john deere 8630 losing all hydraulics and gears too,along with steering,i thought the worst,but I started it back up Saturday and everything was working again so I unhooked disc and drove it closer to where I needed it in case it would happen again and it did,i did clean out both hydraulic sump screens,but the problem keeps coming back after 5 minutes of running,the same thing happens,i did find a center screen,and I was told there was one in very back underneath,and now I know theres 2 in them tractors,i couldn't get the main hydraulic screen out till I find a john deere puller to grab onto it with,is there any ideas you all might have,apparently the pump in the rear end under rockshaft is working,but now im thinking the one under the cab may be acting up,they both seem to work but for about 5 minutes then lose hydraulics again,each time,any suggestionsthanks
 
hi tim thanks for the reply.theres the filter under the cab.i got tractor turned fully to the right this time when I shut it down,is that pump in the area of where the oil filter mounting bracket is?thats were I am starting to hear a gurgling sound now,then the top shaft stops turning,do I have to pull the left tank or is it when I pull the bracket off that holds the filter in front of that?ive got both john deere 8430 8630,8640 technical manuals but for them being about 3 inches thick,they don't show much on where them pumps are,more of the pressures and tests,but no areas of where that pump is at,thats my problem sir,i got all the tools to try to remove this housing with but don't know what to expect when its off,i seen in another post where you worked on a lot of these at one time as well,but if you can call its ok too my number is 361-562-1720,imready to tear down something after my oil bath yesterday from pulling both sump filters at bottom,finally I got clean,now ready to look into it further,thanks for trying to help me,,wish I was working on some of my toys I collect it would be easier buit man I like this tractor with its 8650 motor
 
"apparently the pump in the rear end under rockshaft is working,"

Thanks, Jim for correcting me on the rear pump! I should have remembered that, especially since it only runs when the clutch is engaged, and there's a clutch pressure switch to switch off the transmission lube light while the clutch pedal is depressed and the top shaft/pump are not turning.,

You are RIGHT, there's a lube pump back there but it doesn't feed into the clutch operating pressure circuit, so for our purposes here, it can be ruled out as a problem.

Tim may well be right about the pump ahead of the filter in the front hinge failing, but you need to check the screen in the back, and also the suction line and hose I posted about before.

Since you say there is gurgling in the pump/filter area, it sure sounds like it's getting air and/or the screen may be plugged.

The shop manual tells you have to test the output of flow the clutch pump, and, also doing so will reveal if the pump is sucking air and then forcing it into the system.

(The screen in the front is in the scavenged, dry sump. If it were plugged all 30 or so gallons of hydraulic oil would get pumped forward, fail to be returned rearward, and more than fill the available space up there!

The screen BEHIND the hinge is where the troublesome pump gets it oil, and where brake debris, and the shop towel the last "wrench" left in there, as well as his lost pack of smokes wind up. you NEED to check that! And, yes, I've found both towels and a pack of smokes in those screens!)
 

Here's photo of trans oil pump
mvphoto11934.gif
 
see bob,under the rockshaft there is a transmission hydraulic pump,,not trying to argue with you but I seen pictures of it in the technical manual,,,and as for the screen I cleaned the one out where brake linings get stuck and stopped in,and then in front of it I found the other one and cleaned it out too,it is to the big flow line going up to the center of the swivel hinge area into the center hydraulic filter,both screens are very clean now,,this is happening 5 minutes after tractor is running,im also seeing oil dripping from starter area,i noticed this before all this started up,,filling clutch area possibly and high as starter too sir
 
Yes there is a pump under the rock shaft, it is for trans "lube" only, and there is a sump screen for "that" pump,, Then the next sump screen, the one with the pipe coming from it to the hinge area is for the pump behind the hinge oil filter "That one" is the one you need to be looking at,, It's function is to provide clutch oil pressure and to feed the front pump,, when it fails it gives you exactly the symptoms that you are getting,that pump is a tandem pump (2 pumps in the same body)the second pump in that body is only for emptying the clutch housing, and "that" pump has it's own sump screen,, the Third on in the system....so what we are trying to tell you is "look at the pump behind the clutch housing filter"...
 
Try this first ,put the trany. In in low range (no.1) and see if hydraulic goes away, then try high range (no 2)and see if it goes away . if it does in one but not the other it could be in the quad range . Testing with gauges is really the thing to do .
 
yeah, I did clean out both long sump filters already,and I did find some brake debris on it,and when I started tractor and thought problem was gone but it came back
 
when the center filter is pulled,and you remove the bracket holding it,is the pump in front of it?mounted in an area that can be accessed easy?i know nothing is easy on messing with some stuff on this tractor,and have seen what it looks like in tech book disassembled,but never saw exactly where it is,looks like it would almost have enough room to fit in the the housing but has to be in front of it im told
 
This is one of the easier things to repair on an 8630..it will help to get it in a hard right turn, some times I put a jack in the hinge and jack a bit as the steer wheel is turned when there is no power or hydraulics..
 
gentlemen,i appreciate the good help you all have been,now im not scared to tear anything apart,but didn't know where to look for that pump,see,the technical manual don't show where it is at,well the pump,it will show how it all looks disassembled,but not where to look for it at,im ashamed,my dealer gave me both books,with bout 1000 pages in each on the 8430,8630,8440,and 8640,both nice to have for an early xmas present,but just wished the went into more detail,but ill touch base sunday probably about what I will find when I get into the pump
 

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