Sign in to follow this  
ibendem

2+2 hydraulic troubles

Recommended Posts

I'm having hydraulic troubles with my 6588. I can't seem to get more than 9-13 gpm at 2450psi from the hitch pump at the motor control valve outlet. The tractor has fresh hydraulic filters with the bypass installed between the two elements, fresh hytran (slightly over full), and fresh spin on hydraulic filter. I have cleaned and inspected both orifice screens behind the hitch pump signal line and behind the 5/8 plug on the pump. I have also cleaned and inspected the orifice on the inboard side of the auxillary valve mounting block. When under load, the hitch pump may make no noise at all, or it may load the engine slightly and make noise something like it is cavitating and trying to pick up oil, but only for a few seconds, then nothing again. The tractor was running a grain cart prior to my purchasing it. I'm trying to use it on a hydraulic push off manure spreader. It worked for one load, then was unable to really do much more than start the next load.

In a related, or perhaps unrelated vein, the hydraulic clutch assist rarely works, the transmission brake is only moderately effective, and the TA doesn't shift. I think it stays in low side. I have removed and cleaned the solenoid and spool valve that operates the TA. The TA spool is moved up and down by the electic over hydraulic actuator, but the TA doesn't shift. If the selector is left in the high side, the solenoid gets too hot to keep your hand on it. The low pressure warning light is lit on the dash. The TA worked when I got the tractor, and I dont remember the warning light being lit, but after a healthy pressure washing, my TA troubles surfaced. Also, having little experience with 2+2s, I wonder if it is normal for the MCV pump on the belly to sort of chatter and pulsate pressure? This one sounds something like the pulsating noise from a boxcar magnum. 

I'd appreciate any insight or direction.

Thanks

Share this post


Link to post
Share on other sites

It sounds like the chatter you hear is probably coming from your rear hitch piston pump. That is normal when u use a remote and the pump strokes I believe. But I don't know much about those 2+2s. Does the steering pulsate at all???

 

Share this post


Link to post
Share on other sites

Sounds like you have multiple issues that to me seems like inadequate inlet oil to both pumps. 

Especialy with dash light being on and pump chatter. 

Share this post


Link to post
Share on other sites

Thanks for the replies. The steering doesn't pulsate, it operates pretty smoothly. The lines pulsate, especially the steel line under the cab that terminates at the steering hand pump. The noise coming from the mcv pump area resembles what an electric fuel pump sounds like, though more pronounced and aggressive.  Noise is worse at low rpms and with the steering against the stops. 

If pump inlet oil supply is inadequate, what should I look for to remedy the problem(s)?

Share this post


Link to post
Share on other sites

Did the problems start soon after you changed filters?  Any way something is not together correctly and allowing air to be pulled into inlet?

im hoping someone with more 2+2  specific knowledge chimes in. 

You are having issues with both pumps and the only thing they have in common is oil supply from filters that's why I would be looking in that area. 

Sorry I can't be more help

Share this post


Link to post
Share on other sites

I appreciate just about any help at this point. I never used the hitch pump hydraulics prior to the filter change. I bought the tractor, brought it home, and gave it a full service. The torque worked prior to my pressure washing it, then quit after. Previous owner used it on a grain cart last fall. Odd noise in mcv pump area has been present for the duration of the tractor's life according to the previous owner. He was straight on everything he told me, so I'm hesitant to doubt him on that.

Share this post


Link to post
Share on other sites

OK, the steering seems to work good so front pump should be ok as it requires a lot more oil than any other  functions in the control section of tractor, meaning steering, TA , brakes, seat and lubrications circuit.    I don't like to hear a pulsation in the line though as that is usually a bad piston in the front pump.   As for the red light, you might just have a blown gasket on the plate in behind the MCV. That plate takes the spot a pump would be on a regular row crop tractor.  It merely loops the oil path from pump into MCV but often blows the gasket. You have to remove MCV to get at it .  You should at the very least plumb a gauge into the regulated pressure before looking in the MCV to verify any change that might take place.  I always put in both regulated pressure gauge and lube pressure gauge.

As for the rear pump, unfortunately it could be several different things causing your problem.  It sounds like you flow rated the priority valve but did not say if you flow rated the other valves.  That would be the first thing I did.  If you yield same results you can rule out the priority valve spool at least.   There is a check valve between the aux valves that is troublesome and you have to pull the valve stack to get at it but could be your problem.  The pump has it's own relief valve in the compensator attached to the pump.  There is a safety valve in the back under fuel tank, same place a relief valve is on a open center system.  It merely acts to back up relief valve in compensator in case that one would malfunction and pressure got over  I am thinking , 3000psi.  The only good way to diagnose your problem though is with an isolating hook up that dealers have. It plugs off all outside functions from that rear pump so you are only testing pump and compensator .  It is not a quick hook up though with extra hoses etc that go in and out of a flow rater.   Saves tearing into a pump if problem is out side and vise versa, tearing all the outside valveing apart when problem is in pump. 

Share this post


Link to post
Share on other sites

Thanks Pete. I flow rated the other set of remotes, tractor has only two sets, the relief pressure was the same on both sets, 2450psi, flow was less on the second set of remotes, about 6-7gpm. Cold, the motor control valve flowed just about 9gpm, maybe 10, at 2400 engine rpm. I have the guages to test the mcv and plan to do that tonight. I don't like the hammering either. Bothered me from the first time I heard it. Steering has resistance and isn't as easy as my 1066, but is very managable, something comparable to a 2470 Case. Clutch assist is almost non existent which, along with the ta problem, made wonder about the flow divider. I'll test first, but expect to have to pull the mcv to look for blown passages in the gasket, or debris in the valving. I'm still pretty lost on the hitch pump...

Thanks again.

Share this post


Link to post
Share on other sites

Checked mcv pressures tonight. Pressure at the lube port is 0 in TA, DD, and steering turned to stop. Safety valve pressure is 100 in TA, DD, and drops off a little toward 90 when steering is turned to stop. So am I looking for a large leak in the mcv? Or is the mcv pump junk?

Share this post


Link to post
Share on other sites

I guess if it was mine I would pull that MCV and look for blown gaskets or stuck valve. It's pretty easy to do and relatively cheap. 

Share this post


Link to post
Share on other sites

You have a large leak in regulated circuit or stuck flow divider valve as it takes a lot more than normal regulated pressures of about 270 psi to steer the tractor.   So, if pump will steer at all it is good enough to provide regulated pressure.  I can't remember if the 2+2 uses a sump check valve in lower rear corner of housing behind the mcv or not.  If it does, that is also a prime leak spot. 

Share this post


Link to post
Share on other sites

Figured I would mention what I have discovered on this problem. I pulled the flow divider plug and used a magnet as a weak slide hammer to get the flow divider spool out. Cleaned the spool and the bore. Reinstalled and bingo! had pressure to clutch assist, ta, trans brake, etc. Steering was still pretty decent and light went out on the dash. Put a 14ft 3pt no till drill on it to work out the bugs. Driveline sawed a hole in mcv pump pressure line so I lost a lot of fluid and replaced the line. Later, low pressure light came on, lost clutch assist, etc then blew mcv pump return line (I'm guessing that's what it is, It was a 3/4 line from the pump to what may be a check block up high on the left side of the speed trans). Anyhow, changed the line, light went out, functions returned to normal. Steering is kinda poor at lower rpms (~1000 or less) and the hand pump is leaking like a sieve.

The 3pt raises funny, I didn't know if it would even lift the drill after the trouble I had with the remotes. However, with the rpms greater than 1300, 3pt lever pulled up, draft in center of sensitivity, speed set to fast, hitch pump will growl and arms will start to raise. They move up about 4 inches then stop. Pull back or push forward on motor contol spool lever and when the lever returns to center the arms may move another 4 inches, the may move slowly all the way up, or they may jump up like they are supposed to. Multiple cycles of the motor control lever are often necessary to get the arms all the way up. Rpms must be up and the motor control spool must be used, sometimes to initiate the raising, but always to compete the job. Auxillary spool lever cycles have no effect on performance. Do I have something wrong with the signal line check valve? I've had it out and sprayed it down with brake cleaner and blew it out. I also wonder if the pump is weak. Filters have been changed and hytran level is slightly over full. 

I appreciate any advice.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this