seems i,m getting air in the hydraulic system.all hydraulics work ,but slow.20 lbs.charge pressure,rattling pump,4gallons a minute flow from transmission pump,2200lbs.high side,but gauge is fluctuating rapidly.already checked screen and check valve at filter. i,m almost positive i have a suction side leak at the transmission pump,but not sure where to look.anybody got any ideas.looking through the dipstick hole,there,s lots of bubbles,thanks.
Welcome to HEF! 310 goes well before my time. (I consider myself old) I'm not sure if you're describing 1 or 2 problems here? Hydraulics then charge pressure & transmission? Just looked at Case parts & 310 looks like a manual transmission. :beatsme I always thought a 310 was a crawler & you posted in backhoes - so you have a crawler fitted with a hoe ? Is there a 310 wheeled tractor? Sorry about the guesswork......... But what you're describing does sound like you have a cavitation problem. If all the suction hoses are tightly clamped & not leaking any oil overnight - the only other place that can cause what you are describing is a worn pump.
310a is a 1970 or 1980 something JD backhoe I assume. I did own a 1981 410. I may have been an 410a, I don't really know. My machine built up air bubbles in the transmission every time it was used. If I ran the backhoe hydraulics hard for several hours it would shake more and more as time passed and the transmission oil level would rise from the air bubbles. I would eventually need to turn it off and wait several hours for the oil to settle. I ran it 2700 hrs like that and sold it still running the same way. Never know why it did that.
AHHH a JD ! that would explain it then.......
Do I sense you don't like JD?
Not that I don't like JD. It's just that I don't kow my way around them to well, & you know what is said about old dogs........... I do recall fitting a charge pump to one some time ago - defiinitley not remembered as a pleasant experience. Plus anything built in that era is not pleasant to work on !
yes this is a backhoe,best i can tell a1982 model,this backhoe forms bubbles immediately upon cranking.i was also wondering if the trans dipstick should be sealed,because it says tighten on top of it,mine will not, it just sits there and dances around unsealed.also was wondering if i remove the seat and top transmission plate can i see what makes up the fluid pickup system,such as tubes or some sort of oil pump pickup.thanks for the response.
Your dip stick should be sealed to keep out dirt and water. I would think the transmission has a vent somewhere. I can't see it being completely air tight. My Hydraulic tank on my 310D has a filtered vent. Go to www.deere.com and view the parts in the construction section. You may find something there to help.
310a hydraulics thanks i,ll look there,i was just wondering if the trans pump would draw more volume if the system was under vacuum,if the dipstick wont tighten then naturally you have a loss of suction.
The dipstick would not make a difference, suction side of pump, hoses, pickup tubes etc. would cause aeration. Good luck..
It's been many moons since I've worked on a Deere that old, but I do remember Deere did some weird things with tubing and seals inside the tranny housing. I don't know what charge pump pressure is supposed to be, but if that 20 lbs pressure is in fact low, that could be caused by pressure regulating valve. However, since you indicate the oil get bubbles in it rapidly, that sounds more like a leak in either the suction pipe or outlet pipe of the charge pump going to reverser control valve. Item #19 in pic below is suction pipe, note seals #18, 20, and 22. Item #15 is outlet pipe to reverser valve. Again, note seals #14, 5, and 17. These little goodies are inside the tranny, I can't recall if you can access this piping by removing covers, memory don't go back that far.
thanks for the information,i think i,ll take the top cover off and look inside,hopefully i will learn what makes the hydraulics act the way they do.there is no substitute for experience.thanks,steve
As best I can remember, and someone feel free to correct me if I'm wrong, but the system basically works like this; The charge pump provides oil pressure to the reverser valve, which is the control valve that engages transmission clutch packs. Oil pressure leaves the reverser valve and goes to the pressure reducing valve, which basically keeps the pressure from the charge pump at a steady pressure regardless of engine rpm. Oil pressure then leave the pressure reducing valve and goes to the steering orbit valve to steer the machine, and it feeds oil to the main hyd pump, charges the pump as it were. If there's a lack of supply from charge pump to main pump, it's going to affect the operation of the main hyd pump. Although, one would thing that if you have a lack of flow/pressure from the charge pump, it would affect steering as well. But you haven't mentioned the machine is difficult to steer. Maybe not, can't say for sure about that. Do you know what the charge pump pressure/flow is supposed to be?
the information i could find,says low side at main hydraulic pump should be about 150,and flow should be 10 gallons per minute.
Ok, "low side" meaning the oil that's delivered to the main hyd pump from pressure reducing valve I assume. You see, that "low pressure" at the main pump could be caused by a faulty pressure reducing valve. But it seems the aerated oil is particularly suspicious because that's not normal and there is something causing that. That something could very well be the source of your problem, not the pressure reducing valve
where might i find the pressure reducing valve on this 310a?and how do you go about checking it?also the picture you sent to me of the pump and lines looks very suspicious.if the entire unit,lines and fittings are not submerged in oil,then it seems to me that they could suck air instead of fluid.wish i knew i could see them under the top trans.cover,i might take a shot and look anyway.thanks,once again,the help is greatly appreciated.
Sorry sbarrett, I'm trying to dig around in my head and remember how these things worked, lot of cobwebs in there. Nevertheless, I think I may have some of the operation wrong. What I was referring to as a pressure reducing valve is incorrect, it's actually a pressure control valve, and I'm thinking it's located in the main hyd pump output circuit, not the input (supply) circuit of the main pump. If I'm right about that, the pressure control valve won't play any role in your charge pump circuit, but it would play a role in the operation of loader/hoe functions and steering. So let's work through this again. If memory serves me (which I'm dubious of trusting, lol) charge pump (inside tranny) picks up oil from the transmission reservoir. It sends oil to the reverser control valve on tranny to operate fwd/rev functions of tranny. It then sends oil to main hyd pump (charges hyd pump). Main pump sends oil to the pressure control valve. The pressure control valve sends oil to the steering orbit valve and the loader control valve. I think the pressure control valve acts as a priority valve between loader operation and steering. If you were to be driving the machine, lifting loader arms, and steering at the same time, then lifting the loader arms would take all the oil pressure and steering would be difficult. The priority function of the pressure control valve insures you can still steer while raising loader arms, gives steering priority. It would be nice if someone knew more about the old Deere circuits than I would jump in here.
i think your take on the system is exactly what i,m thinking,from listening to the backhoe run and knowing what the pressures are,it just sounds like air on the suction side leaking in.when you watch the gauge on the standby pressure,it is very good,say 2000-3000,but the needle is just juming wildly,almost so fast the needle is almost a blurr.i,v always felt it was an air intake problem.sounds like an automotive power steering when it.s low on fluid.thanks, steve
My JD experience is mostly ag but there hydrauilcs are similiar ...I think its safe to say its sucking air ..I'd go back to your filter and filter bypass valve From experience if you have piping trouble at the trans pump it wont pump at all ..Cant remember but i think theres o rings that seal that circut between the clutch housing and trans , try over filling it by about 2 gallons thus sealing that area off .. I believe as first said look close at the filter can ...remember it can pull air and not leak oil .. Also did you check your clean out screen ?
it has 2 filters,i think one is on the pressure side,vertical filter,the other i think is a return filter for hydraulic functions,mounted sideways,which one are you referring to?thanks
I could be wrong, but I'm near certain the pickup strainer for the charge pump is item #9
you are correct,i checked it the other night,and found it to be clean,almost no debris at all.
Did this problem just start ??
i bought the machine this way.i,ve never operated one before,just purchased it after watching the previous owner operate it in the yard.when i first got it,and drove for the first time,clutches seemed to be slipping,but i have since found some nails where pins should be in the clutch linkages,done some adjusting and got it to pull decent in most gears.hydraulic functions seem somewhat weak to me,after digging out an old stump the other day the machine seemed real weak,and by the time i got done about 30 minutes,functions seemed really slow.i have since found the oil cooler completely clogged on the outside,maybe the oil just got hot.just really concerned about noisy pump and low pressure at bottom fitting on main hydraulic pump20psi.thanks
Ok well like I said before it sounds like air ...pull the filter bypass valve out and inspect it closely ...and as said before try overfilling it by about 2 gallons . Do you think the machine has been split as far as to put a trans pump in ??
can,t tell,anything this old must have quite a history,thanks
Hey did you get my PM ??
yes thankyou,waiting to hear back