Bobcat 883 G Aux Attachment RH Handle

[AllenJames]

Posted another thread regarding the engine stall at low rpm. Stuck with a down machine now. Pours out black smoke while cranking. No fuses are bad. Fuel primer squeeze ball is solid.

 

[willie59]

I was able to free the stuck stems using a bent paperclip to stick up inside the bottom of each stem to work the brass sleeve and spring mechanisms a lot. They were really jammed up. Then reinstalled the stems and coils. Then got flow both directions on the pwm. Yayy! Then the RPMs were too low, the engine stalled while exercising the valves. Now the exhaust pipe pours out black smoke and machine won't restart. Now to hurry up and wait. Yikes! View attachment 172902

Sounds like you have some extremely sticky valve spools, you may end up having to replacing them for them to work properly. Those type of proportional solenoid valves don't just get a variable voltage signal from the main controller, they get a Pulse Width Modulation signal, basically works in an oscillation of pulses of full voltage on / voltage off/ full voltage on / off, this causes the spool to work in a harmonic vibration to help prevent sticking and give smooth action of the shifting spool, the duration of full voltage on / off determines how far the spool moves thereby giving you proportional control of the valve output.

 

[AllenJames]

All day down. My bad. Going to swap aux stems back to original, in hopes the engine will be under no load. Service advisor at nearest dealer thinks the jammed stem on the aux return line is keeping the engine load too high. If I get it running, gonna have to spend 300+ on a set of stems.

 

[willie59]

The engine load is most likely one of the aux spools now stuck on. Quick remedy, if you have quick couplers for the attachment connection up front, is to make a jumper hose at the quick couplers to allow oil to flow through the auxiliary circuit.

 

[willie59]

What kind of shape is the hydraulic oil? Is it contaminated by water? Or possibly was in the past and has since been flushed out and replaced. Water in oil will cause corrosion of valve spools such as these and cause problematic operation

 

[AllenJames]

Removed both stems. Both brass spool sleeves and springs are moving as freely now as they did earlier once I unstuck them using a big paperclip bent as a o-ring hook. I put the stems back. Left the coils off. Engine no run. Seems to be getting no fuel, yet huffing heavy black smoke upon cranking. Sqeeze ball is tight with fuel pressure. Then put coils back, sets of originals as found initially. Will try to make a QD hose to allow fluid flow through the circuit. Overnight sitting should cool off enough to get glowplugs to cycle. Sunshine has been hitting the back side all day. Kind of stuck out here in central wyoming, hours from civilization.

 

[AllenJames]

The hydraulic fluid went low today after working with stems. I see an orange glob floating by the sight- glass. Thanks Willie and Crewchief for hangin' in here w/ me.

 

[AllenJames]

Maybe not related to today's engine load and hydraulic pressure, but I've noticed another broken part - seen in the lower right corner of this photo, there is supposed to be a spring-loaded switch with a roller wheel. Present and working is the switch for the right lever. Broken and missing is the roller switch for the left lever. I've been hearing the slightest pressure flowing on the left side as long as I've used this 883G. When the left lever centers, the switch isn't being pressed.

 

[willie59]

Those are micro switches used to activate the back up alarm

 

[AllenJames]

Got the machine to start right up and run great today after I put a host (with all the right fittings, etc) across the auxiliary QD in/out ports. Then discovered that once I flow fluid either direction, that AUX fluid pressure is remaining constant and dragging down engine speed. Moving lots of fluid very fast. I take it this is bad for the main pump. I've degraded the situation, these past two days, because before swapping original H1 & H3 solenoids and stems (as a test, using all original O-rings, etc.) the engine ran, and machine was usable for bucket and fork jobs. Seems I've still got one or both stems jammed in a place now where fluid flows under pressure and is not controllable anymore. Somehow the flow is constant right as I turn the key to start the engine. I think I had better leave the machine off until new stems arrive, etc. Can anybody suggest a work around to get the AUX fluid circuit back into a "neutral" no pressure condition so I can run safely without having to jumper hose across the AUX QD's? Perhaps there's a spool stuck too, inside the control valve. I better not take anything else apart without at least new o-rings and seals on hand.

 

[AllenJames]

A pair of new solenoid stems resolved the entire problem. Nice to be able to use attachments!
I learned a lot about 883G during all of this.

 

[willie59]

Indeed, good to hear you got it sorted out