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Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 5316
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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I have a 444E wheel loader. Was driving it in forward and went

Customer Question

I have a 444E wheel loader. Was driving it in forward and went to reverse now it wont move either way, discovered it was very low on hyst. fluid, refilled-still nothing. Hyst pressure lite on, sometimes acts like it wants to go but wont. Seems like maybe air is trapped somewhere?? do I need to bleed something? I have let it sit for several week thinking that might help but didnt. Thanks Steve
Submitted: 2 years ago.
Category: Construction and Road Equipment
Expert:  Dan replied 2 years ago.
Hi Steve. My name is***** will be glad to try to help. First check ther hydraulic filter for metal and debris and the oil condition for burnt smell or discoloration. If found then it indicated an internal failure. Aluminum indicates a converter failure. Check the directional control switch for power in and out in all forward and reverse gears to verify you are getting power to the transmission solenoids. If so and the oil is clean the next step is to have your pressures tested and confirmed they are in OEM specs. Let me know.Also be sure to check all your fuses and relays
Customer: replied 2 years ago.
I have replaced all filters and screens, fluid is clean. I assume all soleniods and switches work as it sometimes tries to move both directions . It acts as if their may be air trapped somewhere. Do you have any experience with the JD444E specifically? I understand the general theory of operation and have manuals, really looking for someone with experience with this unit. Thanks
Customer: replied 2 years ago.
I may be in and out so my response may be delayed.
Expert:  Dan replied 2 years ago.
Hi, My apologies. I was thinking of the 544E when I answered for the powershift transmission. This one is the tonka toy with the hydrostatic drive. I worked for Nortrax before going to Cat and yes I do have experience on these machines and many others but do you have hydraulic test gauges to check pressures and a flow meter? Also and OHM /Volt meter and test light? Never assume anything when it comes to troubleshooting electrical and hydraulic problems. Always test and confirm or you can very easily overlook something simple or something in general causing a lot more troubleshooting time than needed to isolate a problem.The most common wear item is the directional control switch bot you will need to test it for power in and out in each position and also for power at the solenoids. Try swapping relays when this problem occurs to see if you possibly have a sticking or faulty relay. Check your harness and all grounds as well. If the electrical tests out ok then be sure you have good charge pressure for the pumps to engage.You should see 270+-43 PSI of neutral charge pressure and 185+-43 of operating charge pressure. Confirm you have good charge pressure. Then test your main pressure. You should have 5700-6300PSI and if not check for a faulty relief valve or possible Main pump or failed pump drive coupling. If ok and the electrical tests ok and no metal was found in any of the filters or strainers indicating a pump or component failure let me know. For the brake HI/LO transmission pressure should be 300-330 PSI with max leakage between clutch packs 15 PSI and the brake unloading valve pressure should be 2340+-50 PSI. Your service book has the procedures on how to check these pressures. Let me know what you get for results and if there was any fine metal noted at all in the filters or screens as there should be none.
Customer: replied 2 years ago.
I think it is the hydo charge pressure since the light is on, I can get to go off by revving but still won't move. Is there a way to bleed the system since I think we ran it pretty much out of hydro-static oil and possible sucked air?
Expert:  Dan replied 2 years ago.
Thanks for the updated info. No or low oil in a hydrostatic system is never a good thing as with all the close tolerance machined internal moving components they will fail and start to come apart quickly. With full system oil now you should still see some response if the pumps are ok. You might not have found much metal when you looked as it did not have time to travel through the system but you still could have pump failure on your hands unfortunately. The next step is to check your charge and main pressures to see if either are within specs. Lets hope that it is only the charge pump and not the Main pump and drive motors. There should be some plugs on the pump body you can crack open as well as the pressure lines to see if you have any air with the machine off but I doubt this is your problem unfortunately. Let me know
Expert:  Dan replied 2 years ago.
Hi, Did you get this resolved? I wanted to follow up to see what you found and if my information was helpful to you or if you still needed more help? Let me know and I will get this question closed out for you if you don't need further help with this. Please feel free to rate or accept if you found my information helpful as that is how the experts receive credit for their time helping on the site.
Customer: replied 2 years ago.
Dan I have not had time to get back to this but will let you know when I do.
Expert:  Dan replied 2 years ago.
Sounds good. thanks for the update. Have a great weekend

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