8027 zts Intermittent swing

[ausdml]

Hi

I have an old 8027zts excavator with an Intermittent boom swing issue, it is very slow to switch between swing and slew.

ill press the button on the left joystick to swing and it wont switch just keeps slewing, ill give up trying and carry on then after a few minuets it will eventually switch from slew to swing by itself and from then on it will switch between the two as it should.

This will remain the case if i regularly switch between the two but if its not selected for a while then it will be slow again.

I'm thinking its a solenoid valve issue either a sticky valve or a week coil. i have located a valve block with two solenoid valves one appears to be controlling the 2 speed tracking but i cant identify the other I'm guessing this the one i need to investigate.

if anyone could confirm this or suggest another cause i would be greatly appreciative.

Many thanks

 

[Alan]

I'm no expert, did a bit of research and here's what I got. Hope this helps.

Your diagnosis sounds spot-on, classic symptoms of a sticky solenoid valve. The fact that it works fine once it switches and continues working with regular use points to a valve that's sticking when cold/idle, then freeing up once energized and moving.

Before replacing anything, try this: when it's acting up, tap on the suspected solenoid with a wrench handle while pressing the swing button. If it suddenly engages, you've confirmed it's sticking.

Also check:

- Electrical connections at the solenoid for corrosion​

- Voltage at the coil when button is pressed (should be 12V or whatever your system voltage is)​

- The solenoid itself may just need cleaning - sometimes you can remove it, flush with brake cleaner, and reassemble​

If the second solenoid on that block isn't for tracking, it's almost certainly your swing/slew selector. The intermittent nature and the fact that repeated cycling helps really points to mechanical sticking rather than electrical failure.