CPS Plant Case Studies
Hitachi Zaxis ZX470-3
One of our customers called me because he could not get the machine to start as it had been parked up for a number of months. I bought all the parts from stock that I thought I would need – including fuel filters, batteries and connectors. When I got to site the engine was able to turn over but would not fire up. I plugged in the Hitachi diagnostic tool and read the fault codes. There was no active fault and using the tool I could read the live data and see there was sufficient fuel pressure for the machine to start.
Now that I knew there was fuel pressure I could concentrate on either an electrical or mechanical fault to the injectors. I removed the rocker cover to expose the injectors and I checked the power going to all the injectors. They were all receiving a signal from the ECU so I was happy that the fault was not electrical.
The fault had to be in the injectors themselves. We removed the injectors and got our local diesel repair workshop to overhaul them. He advised that the injectors had seized as a result of water in the fuel. We went back to site to re-fit the injectors and drain the contaminated fuel. We fitted new filters and clean fuel and bled the system up.
The digger started up straight away and to date has been going perfectly. Customer was happy with the fast turn around.
A customer had a bought a new hedge cutter for their Volvo digger and found that the digger wasn’t able to drive it. We went out to site, and checked the machine auxiliary line flow and found it to only at 80Lt per minute. The machine should put out 120Lt per minute!
We investigated the problem and found that the control unit had been disabled as a result of a throttle problem. From previous experience I know that these machines only operate at 75% of their capacity when the ECU is disabled. We used diagnostic tool to read the faults and realised that there was a potentiometer was faulty. We replaced the faulty unit and we repaired throttle linkages and enabled the ECU again, we set up the auxiliary line flow using the laptop to 120lt per minute as per factory specification.
The customer was delighted as another workshop had previously advised that he would have to replace his machine as it wasn’t fit for purpose.