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We are operating a CAT 311B excavator 2003, with serial # XXXXX…

Question

Answer 1

Answered in 6 minutes by:

7/29/2012

Technician: catmastertech, Technician replied 10 years ago

catmastertech, Technician

Category: Heavy Equipment

Satisfied Customers: 4,196

Experience: 25 years Cat, 3 years Case

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catmastertech :

What do you mean by, without computer?

catmastertech :

Are you sure that is the serial number, it is not working on my search page.

catmastertech :

Normal mode when no power is sent to travel speed solenoid (LOW SPEED selected) no pressure is in the circuit. It will be in low speed anyway.

catmastertech :

You must have other problems. Have you tried selecting speeds as soon as you start the machine to see if it will change speed?

catmastertech :

You can disconnect the small line going to each travel motor. This is the line to shift to HIGH SPEED.

catmastertech :

It is common for machines with high hours (around 7000 hours) to have leaking seals in the rotorary joint (swivel joint) located in the center of the machine. When these seals fail, oil pressure is lost to travel, making it feel weak and is very weak when oil is warm.

Customer:

The computer for me is the electronic box under the seat.

The serial number I gave you is the one that is on the plate.

Customer:

The electronic box under the seat, is what I call the computer

That is the correct serial number on the plate.

catmastertech : So I guess you have no indicators either. Is this due to a failure? Are you operating in backup mode?

catmastertech : What happens when the oil is cold?

catmastertech : Is this a high hour machine?

catmastertech : Have you resealed the swivel joint?

catmastertech : Or are you just planing to block off the travel speed lines?

catmastertech : This machine is not the same as the US versions. Most of it is the same but it does have some odd parts about it.

Customer:

Thank you so much for your precious answers.

We are now thinking to try to block off the travel speed line tomorrow.

Customer:

I will let you know the results righ after. I hope it will work.

catmastertech :

It will hold the motor in low speed if it was getting oil pressure in the travel line. My past experience has been, the swivel joint seals will need replacing.

catmastertech :

I will be looking for your reply. Please remember to provide feedback when we are finished, I am glad I could help you.

Answer 2

Technician: catmastertech, Technician replied 10 years ago

Possible pump failure. Replace all hydraulic filters and cut open old filters to inspect them for metal.
Smallest spin-on filter is pilot hydraulic control pressure for joysticks and travel pedals.
Joystick main functions are not electronic, only push buttons on the handle would be an electric control. All foot pedals are pilot hydraulic control except a hammer switch pedal (add-on option only). I assume you mean you are operating the machine in back-up mode by switching off the ecm at the switch in the right hand console. This turns of dash at the same time. It also sets pump power to 80%.
The filter in the middle of the machine is case drain form the pump and the motors (travel and swing). Case drain flow testing can help determine which has failed if metal is seen here.
The large canister filter on the side of the tank is the return filter. Oil from the main control valves and cooler returns through this filter. Look for debris other than metal in this filter. It could be from damage to a cylinder or hose and will help identify source of the problem.
If metal is seen in all three filters, major failure has occurred and the entire hydraulic system needs disassembly and cleaning to remove all the metal. If this is not done, the machine will have problems with the valves sticking and become uncontrollable.

Answer 3

Technician: catmastertech, Technician replied 10 years ago

Thanks for accepting my answer, I am glad I could help.

I would recommend the dealer rebuilding this pump. Drive group is difficult to set pre-load on bearing sets. Control heads have several small pieces that must be kept in order for proper operation. Ask them to inspect it and give you a price to compare the price for a Reman pump. Sometimes it will be cheaper to go with a Reman pump (Factory rebuild).

I would drain the tank and replace the oil. Open the cover and inspect the tank for metal in the tank and pump suction strainer. Remove the tank and have it cleaned if debris is found. Since return filter was clean problem was caught early. Hopefully, it has not sent metal out to the valves or motors. After it is running again, change filters after a day of running and again after a few days. Cut them open and inspect for metal each time. Keep changing filters until no metal is seen. Have the oil sampled for cleanliness, the dealer can help verify it is clean.

The serial number is stamped on the cab frame below the right window. A tag and a frame stamp is together in the same spot. Usually it is a few centimeters from the front.
"Grey Market " is what we call them, it was made only for Japan and manuals are available only in Japanese. Many parts match but, sometimes it will match to a different US or European models. You may find parts from a 110B CAT will match.

Please let me know if I can help again. Thanks for using JustAnswer!

We are operating a CAT 311B excavator 2003, with serial # XXXXX…

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