Hi all, newbie here, I own a S70E Boxcar special that I use for moving manufacturing machinery.
My monotrol pedal is giving fits, I have neither forward nor reverse. However this is intermittent, after several clicks back and forth then I usually get transmission engagement back. Today was different where I could not get any engagement and thus could not move.
Wondering if there is some interlock problem, i.e. foot or parking brake sticking that's inhibiting the monotrol action. I've checked and topped off the transmission fluid level.
Another curious symptom is that I have zero steering capability when this is occurring, so again wondering if something like the parking brake is interlocking the main hydraulics?
Another angle on this is that sometimes the lift sits for a month at a time and I do have some leaks....so wondering if I could possibly be air-locked?
Thanks for any suggestions...I guess I understand that something is wrong in the hydraulic control circuit but not sure how to proceed for repairs or testing...would rebuilding the "plate" on top of the transmission where all the monotrol lines plug in be a place to start?
TIA
-Matt
Showing items 1 - 4 of 4 results.
This problem will usually show up once the units condition has been let go. (many small leaks, or some not so small)
Air can enter the steering/transmission hydraulics when engine off, and then an air lock can result.
Bleeding the air out is only a temporary fix...until the next time the unit is parked for a longer period of time.
FIX ANY EXTERNAL LEAKS 1ST, Then you may have to reseal or replace the pump or shaft seal.
Note: When running the unit in this condition...the pump is running dry!!
By the way the recommended oil is J20A or J20C Universal tractor transmission (was an update in the early 80's)
Hi, thanks for the replies. I first went down the path of troubleshooting the parking brake solenoid...seems to be fine. I disconnected the little steel pipette that brings fluid back to the valve body and I was just getting a little spurt of ATF now and then with the solenoid energized with an alligator clip to 12v.
Reading, found what Joe posted about trans and steering being common.
I will try the hex-plug plus I'm wondering if I've dropped fluid level down far enough to entrain air....the problem has gotten worse over a couple troubleshooting sessions. The dipstick says to check engine running and fluid hot, which I have trouble achieving the temperature. Any idea how much overfill should be present when the engine is off and the truck has been sitting for ~1 week?
Last session I know I was getting air as I had my ear right up next to the orbital motor for steering and I'd hear little slugs of fluid go thru it at times, followed by slugs of air. I had assist for those instances when there was fluid.
Still have some pretty good fluid leaks on the floor and leaking from the power steering cylinder rod glands (have a rebuild kit) and the oil drips were "foamy". Will tear into it again this weekend and see where I get. Thanks for the replies thus far.
Trens and steering use same pump. Pump should be mounted to bell on right side of truck. There should be a hex headed o-ring plug on top of pump. With engine running, loosen this plug - when oil starts to come out, the tighten plug. That should bleed off air. That was a common problem on that series. Hope it helps.
matt
first check safety start switch is working behind park brake lever.it,s activated by a rod from side of lever. second check monotrol switchs ,you need to get contiuity through 1 switch then out through the other to make drive , sounds odd but once you turn over the red pedal you,ll see how it,s wired. it,s wired in a way so that if both buttons are pressed nothing works. also check inching spool is working properly.
steering
remove steering wheel and column ,remove plug from middle of housing onback of steering unit. screw inner plug in a little ,this boosts the pressure to the steer axle and may help.don,t go too far in though 2 full turns max. if this don,t help you have other problem.
hope this sends you in the right direction
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