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i own a terex 644 telehandler . rough idle until i operate…

i own a terex 644...
i own a terex 644 telehandler . rough idle until i operate hydraulics (clears up ) . it feels like motor is under a load as soon as i operate hyd. the idle gets smooth again.i have checked the solenoid on pump . it has current only when starting machine , as soon as it starts the current goes away.i have no manual and there is no one in town capable of working on it.is there another pressure relief solenoid in the system, i cant seem to find one.
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Answered in 7 hours by:
12/1/2013
Mechanic: Dan, Technician replied 8 years ago
Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 14,658
Experience: 17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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Hi my name isXXXXX will try to help. Please post the complete engine model and serial number from the engine tag so I can be sure to provide you the correct information.
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Customer reply replied 8 years ago

family# XXXXX engine model # XXXXX thats all thats on eng. tag. Terex 644 telehandler 2005 model

Mechanic: Dan, Technician replied 8 years ago
Thanks for the info Tony. Could you also provide the machine serial number if you can so I can see if I can obtain a hydraulic schematic for your serial number?
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Customer reply replied 8 years ago

S/N TH0606B-6195 . If i remove the pump, can i start the engine to eliminate the trans as a possible problem?

Mechanic: Dan, Technician replied 8 years ago
Yes you can and that is a good way to confirm or eliminate a hydraulic issue. Cut your trans and hydraulic filters open for a sample using a filter cutting tool or equivalent to prevent metal shavings from contaminating your sample. then cut a decent sized square sample and squeeze out the excess oil in a vice. Look for metal in your filters. Check your return circuit for restrictions and your relief cartridges at the main control valve for sticking. If this pump is a variable displacement piston pump you could have your pump swash plate stuck in full stroke. I wasn't sure off the top of my head what style main pump you have for your serial number. If a variable displacement piston pump, One way to check is to disconnect the small pilot pressure signal line to the pump and run a hose into a bucket before removing the pump and this should make the swash plate return to neutral removing the load from the engine. If not then remove the pump and see if it resolves your problem. This will tell you if there is a mechanical failure inside the pump. Let me know
Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 14,658
Experience: 17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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Customer reply replied 8 years ago

Your talking to a dummy. not surewhat to do . i have a picture of the pump on my phone , i can send to you. there are three lines to the pump. big line is suction , medium size line ,i presume is discharge and a smaller line (3/4" or so )is return to tank?

Mechanic: Dan, Technician replied 8 years ago
Hi Tony, It sounds about right but if you can upload a picture of this pump using the paper clip icon above I can better confirm this with you. By chance if you can look on the pump for a metal tag and give me the information on that tag it would be helpful. Let me know and Ill help with what I can. I think the easiest way is to check for metal in your transmission and hydraulic filters that would indicate a problem in either circuit. If found in your hydraulic filter then pull the pump and see if the load is still present. Now by doing that you are eliminating the entire hydraulic circuit so you want to be sure the return has no restrictions and the relief valves check out ok with no damaged o rings or debris. Let me know
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