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345 cat excavator sn Ags 2348 this machine has low hydraulic…

345 cat excavator sn Ags...
345 cat excavator sn Ags 2348 this machine has low hydraulic power. plenty of fluid, new filters. need to diagnose hyd system.
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Answered in 32 minutes by:
11/6/2013
Mechanic: catmastertech, Technician replied 8 years ago
catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 4,002
Experience: Field service technician for CAT 19 years.
Verified

catmastertech :

Hello, Have you tried using the backup mode?

Customer:

whats that

catmastertech :

The switches located in the rear of the right armrest.

Customer:

what do they do

catmastertech :

One switch will bypass the pump controller and the other switch is to set the throttle.

catmastertech :

This is used when a failure of the pump controller is present and will allow some use of the machine.

catmastertech :

Do you still have the owners manual?

Customer:

if we flip the switch the hyd should come up as long as we don't have a pump prob. we also have a prob with the throttle switch which we have replaced the enginewill go to full pwr, but we not throttle down unless we kill the motor.

catmastertech :

You have tried the switch and the pump is normal now?

catmastertech :

Are you saying your throttle dial is not working correctly?

Customer:

have not tried anything. to wet to mess with it today trying to get ahead of the problem for tomorrow. the throttle is not working correctly. will go to full pwr but will not dial back down

catmastertech :

The dial or the backup switch?

Customer:

the dial

catmastertech :

Ok, is the engine ecm warning light on?

Customer:

no

catmastertech :

You need to check the harness from the dial back to the ecm. The wiring must be missing a connection to not idle back down. Does it step up with each position on the dial?

Customer:

it does

catmastertech :

Does the one touch idle button work on the right joystick?

Customer:

have not tried that

catmastertech :

Since the dial will step up, the harness should be ok. If the one touch button is stuck down, this could be the issue.

catmastertech :

Just disconnect the leads from the handle and the throttle should return to normal.

Customer:

will check that. would that have anything to do with the hyd.

catmastertech :

Is the engine stalling or the pump not lift a load?

Customer:

no

catmastertech :

The pump is lifting loads ok?

Customer:

yes, but all functions are slow

catmastertech :

Do any functions act jerky?

Customer:

no

catmastertech :

How is the travel acting?

Customer:

it walks slow, swings slow, digs slow

catmastertech :

Ok, do you have pressure gauges?

Customer:

we do

catmastertech :

I would start by checking the pilot pump pressure. It should be about 575 psi. This pressure is needed to control all the functions.

catmastertech :

Second test the main relief pressure, I have seen several wear out the main relief and the machine will feel weak and slower than normal.

catmastertech :

Main relief pressure should be about 4900 psi.

Customer:

can you show me where to plug into the system to do these checks

catmastertech :

The pilot pressure tap is on the solenoid manifold valve under the pump or you can connect at the tap next to the pilot filter.

catmastertech :

The main relief is tested by the taps on the pump where the main pump lines connect to the pump.

catmastertech :

I will see if I can find a picture.

catmastertech :

This is the pilot manifold.

catmastertech :

Full Size Image

catmastertech :

Use the taps 2 and 3 for main pressure.

catmastertech :

Tap 1 is powershift. this will change under pump load. This tap has pilot pressure but, is controlled by the ecm. If pressure does not change when loading the pump, the powershift pressure control current is not coming from the ecm.

catmastertech :

The powershift pressure should be about 400 psi with no load on pump. when load is applied, it will drop to about 100 psi, then return to aroound 400 psi to prevent the pump stalling the engine.

catmastertech :

If it does not, the solenoid may be stuck. This could cause the machine to be slow as well.

catmastertech :

Full Size Image

catmastertech :

  1. Attach a 60000 kPa (8700 psi) pressure gauge to pressure tap (2) .


 



  1. Start the engine.


 



  1. Place the machine controls at the following settings: Power Mode and engine speed dial "10".

    Note: The engine will not reach maximum no-load speed until the hydraulic tank pressure has reached the operating level.




 



  1. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).


 



  1. Open the bucket until the bucket cylinder rod is at the full retraction.


 



  1. Check the main relief valve pressure setting at pressure tap (2) .

catmastertech :

  1. Return the control lever to the NEUTRAL position. Adjust the main relief valve pressure to 34320 ± 490 kPa (4980 ± 70 psi).


 



  1. To adjust the main relief valve pressure, loosen locknut (5) and turn adjustment screw (4) until the pressure gauge reading at pressure tap (2) is 34320 ± 490 kPa (4980 ± 70 psi).


 



  1. Tighten locknut (5) to a torque of 50 ± 10 N·m (37 ± 7 lb ft).


Note: Turning adjustment screw (4) clockwise increases the pressure. Turning adjustment screw (4) counterclockwise decreases the pressure.


Note: Always make final pressure adjustments on pressure rise.

Customer:

well let me try that. will you email me tomorrow afternoon. will have a lot more info

Customer:

will try that, will u email me tomorrow afternoon to see how it goes. will have a lot more info then

catmastertech :

Ok, I may not be available until late but, I will reply as soon as I can. I am glad to help.

catmastertech :

I will switch to the Q&A format, this will notify me when you make a post.

catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 4,002
Experience: Field service technician for CAT 19 years.
Verified
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Mechanic: catmastertech, Technician replied 8 years ago
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catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 4,002
4,002 Satisfied Customers
Experience: Field service technician for CAT 19 years.

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