Combilift C8000:
Correct steering system bleed procedure

Hi all, I have read a couple of related posts for steering issues but not for a C8000, might be the same but not sure.

My problem is hoses were replaced and I did the steering re alignment procedure and cracked hoses on front cylinders to check for air and I'm getting none, I drive the unit and within a sort time the right front wheel goes out of alignment and when I realign and put directional lever to neutral both front wheels creep out of straight forward facing alignment.

Any help appreciated
  • Posted 2 Jan 2023 13:37
  • Discussion started by MicD
  • Western Australia, Australia
MicD
Showing items 1 - 9 of 9 results.
Hi
The steering purge should be done by the operator regularly, if it has not been done for 3 weeks that is an operator issue. If not done this would also increase tyre wear. Assuming there is nothing mechanical wrong, a purge may need be daily or a couple of times per day if the truck is running mostly long distances with long loads in sideways mode all day. There should be a decal in the cabin explaining the way it has been explained below. The explaination is also in the manual. YouTube Video link https://www.youtube.com/watch?v=g5F_g_tK75s

Hope this helps,
Richard
  • Posted 20 Feb 2023 19:51
  • Reply by Richard_Irwin
  • Monaghan, Ireland
Hi BLey,

I had both cylinders rebuilt and finally bled them, the unit has been running for 3 weeks and I've just gotten a call while I am on holidays asking how to realign the steering, so I am obviously getting air from another source, steer lock stop adjustments are ok.
  • Posted 20 Feb 2023 16:15
  • Reply by MicD
  • Western Australia, Australia
MicD
Yeah its left or right as in sitting in the cab.

When your in side mode you should still be able to steer the cylinders all the way in but ive seen the adjustment of the RH cylinder being to short preventing the piston from retracting all the way. The poppet valve in the piston never opens for bypass and you wont be able to steer the LH cylinder in to its fully retracted position.

As long as the adjustment of the cylinder is good and the poppet valve was checked for good operation during the rebuild, you should be able to get the LH cylinder to steer straight if you keep steering against the pressure relief/steering lock.

If your thinking its just to much air in between the two cylinders combilift tech support should have a parts list to build a bleeder line that runs between the two hose fittings on the left cylinder to help with the air trapped in between the left and right cylinders but you would have to go through the support line as Richard_Irwin suggested.

I also forgot to mention when bleeding the system you should steer the cylinders all the way out and keep turning the steering wheel a full rotation or two after the cylinders are fully extended and do the same when you fully retract them.
  • Posted 21 Jan 2023 15:03
  • Modified 21 Jan 2023 15:51 by poster
  • Reply by BLey
  • Ontario, Canada
Hi MicD,

Just checking if you have submitted the "Technical Support" form at the bottom of the www.Combilift.com web site. When you do we will assign it to our technical engineer based in Australia. If he could call you I think it would clear up a lot.

Note there is no login required and no cost for this support.

Thanks,
Richard
  • Posted 19 Jan 2023 20:39
  • Reply by Richard_Irwin
  • Monaghan, Ireland
Hi BLey
I have had both front steer cylinders rebuilt professionally and have reinstalled and have done your bleed procedure but I am still getting a lot of air when I crack the rear fitting on the left cylinder, I have done it multiple times now and left cylinder won't retract fully

Just to be positive l, the right hand side is as you sit in the cab facing forward yeah?
  • Posted 19 Jan 2023 20:02
  • Reply by MicD
  • Western Australia, Australia
MicD
Thanks Richard for your information, I have taken both front cylinders off for rebuild, will let everyone know.

Cheers
Michael
  • Posted 9 Jan 2023 10:46
  • Reply by MicD
  • Western Australia, Australia
MicD
Hi

You have already recieved great direction and advise.

But if you still need technical support for this or any other issue, please go to www.combilift.com, scroll to the very bottom, you can submit a "Technical Support" request. The form asks for truck SN, contact tel no, etc to help identify the problem and to contact you back. The tech team will then contact you. Here is a direct link here https://warranty.combilift.net/technical-support-form/

Hope this helps,
Richard
  • Posted 5 Jan 2023 20:13
  • Reply by Richard_Irwin
  • Monaghan, Ireland
I would check for front steer cylinders bypassing first. All u have to do is start the lift. Put truck into side mode. Extend the front clinders all the way and rotate the steering wheel one full turn on the pressure relief. Then retract them all the way and rotate the steering wheel one full turn against the relief.

Change the mode from side mode to forward mode. Then back to side mode. Let the truck move the front steer cylinders to 90 and stop.

Now that the system is bled again go to the right hand side of the truck. This is the master cylinder. All Combi's with this steering system are all made the same and will always have the master on the right hand its also physically bigger.

Take the front hydraulic hose off of the cylinder. Cap and plug the hose and cylinder. Mark the chrome rod of both cylinders with a line approx 1in away from the cylinder end. (Use a measuring tape to mark)

Now with the truck running and in side mode turn the steering wheel at least one full turn each direction. Then check the steer cylinders.
If either cylinder has extended (mark has moved outwards) that clkinder is bypassing and will need to be replaced.

Most of the time one will be bad and the other still okay. Sometimes both are bad.

If both cylinders show to be good. Make sure the master cylinder (rh) is adjusted properly and that the stop bolts on the deck are properly adjusted. These need to be adjusted for the purge valve in the master cylinder to work properly.

These trucks do drift when the key is shut off or dierection lever is placed into neutral as hydraulic pressure creeps through the valve but the truck should move them back into position when a mode is selected. And I believe there is a one way check valve that prevents this on the new trucks installed near the 6 port steering valve. But im unsure of your truck has this.

I have also heard of the 6 port steering valve causing this from other techs but have not personally seen it myself.

Bleed procedure is just all the way in and then all the way out several times. No need to crack open lines.

Hope this helps at all.
  • Posted 3 Jan 2023 03:22
  • Modified 3 Jan 2023 03:25 by poster
  • Reply by BLey
  • Ontario, Canada
hi micd
your two front steer cylinders req replacement one is master and one is slave you have a bypassing fluid problem so when in straightforward you have an internal leak and this is why the unit will crab inwards im sure combilift will comment on this post to help you
  • Posted 2 Jan 2023 20:40
  • Reply by skyreach
  • Victoria, Australia
reach for the sky

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