AHC Height Accumulator Bleed Screw Sheared Off (1 Viewer)

[NoTempoLimit]

Attempted to do the Paddo AHC bleed procedure today. The bleed screw on the Height Accumulator was so tight the outer part of the bleed screw sheared off. Most of the threaded part of the bleed screw remains in the threaded hole. The threads are probably galled or nearly fused together.

I went ahead and bled the system from the 4 bleed points near the globes. None of those bleed screws were stuck. So at least I got some fresh fluid in there, even though the height accumulator did not get bled and that was the first in the order of Paddo's procedure.

What to do now? Hopefully I can drive like this for a while. I have experince with threaded fasteners and there is no easy way to get the rest of that bleed screw out. It seems to me the entire accumulator would have to be removed from the frame in order to successfully remove the broken part (plus any metal chips created by the removal process). That seems like something that would have to be done by someone experinced with servicing the AHC system. And it would likely mean all the fluid would drain out. Am I wrong about that?

Thanks!

 

[Malleus]

Sounds about right. That really sucks.

 

[NoTempoLimit]

As long as I can keep driving it does not suck that bad. I know those threads did not budge so the bleed is still closed. The nipple and the hex are gone.

Having thought about it, it -might- be possible to get the broken part of the bleed screw out, but it would have to be done on a lift. Perhaps with the wheels extended all the way you wouldn't loose that much fluid. What fluid you do loose might flush out the metal chips.

I'm not going to do it myself.

 

[NoTempoLimit]

Damping feels noticeably better after getting the old fluid out.

 

[IndroCruise]

Attempted to do the Paddo AHC bleed procedure today. The bleed screw on the Height Accumulator was so tight the outer part of the bleed screw sheared off. Most of the threaded part of the bleed screw remains in the threaded hole. The threads are probably galled or nearly fused together.

I went ahead and bled the system from the 4 bleed points near the globes. None of those bleed screws were stuck. So at least I got some fresh fluid in there, even though the height accumulator did not get bled and that was the first in the order of Paddo's procedure.

What to do now? Hopefully I can drive like this for a while. I have experince with threaded fasteners and there is no easy way to get the rest of that bleed screw out. It seems to me the entire accumulator would have to be removed from the frame in order to successfully remove the broken part (plus any metal chips created by the removal process). That seems like something that would have to be done by someone experinced with servicing the AHC system. And it would likely mean all the fluid would drain out. Am I wrong about that?

Thanks!

Major PITA!!

Here are some past experiences ….

AHC Accumulator Bleed Valve -- broke off. (Post #1)

…. including some wise words from @PADDO and @uHu where they highlight the dilemma you already have discovered in getting rid of the pressure ‘locked’ in the Height Control Accumulator (HCA) by its solenoid valve. This pressure will not be released simply by bleeding at the ‘globes’. Other posts follow which further highlight the hazards.

AHC Accumulator Bleed Valve -- broke off. (Post #13)

The aim could be either (i) to enable a safe attempt at extraction of the bleeder with an EZ-out with the HCA in situ (drilling probably not required because the bleeder is hollow), or, (ii) safe removal of the HCA assembly for benchwork to attempt to extract the broken bleeder screw under better conditions.

So how to be sure that the HCA has been depressurised when the bleeder cannot be released?

There is the following suggestion from @YvesNL to relieve HCA pressure – obviously, be very, very careful of the pressures involved (projectile strength eye protection and gloves as a minimum and stay out of the line of fire in case of any residual pressures and beware of vehicle movement):

AHC Accumulator Bleed Valve -- broke off. (Post #23)

Meanwhile, there is no great rush. If the Height Control Accumulator continues to work properly, then with the HCA bleeder stuck in the closed position the AHC will continue to work if it was working previously.

Bleeding of the AHC system at the Actuators (to which the ‘globes’ are attached) will still work reasonably well without use of the HCA bleeder but may take additional bleeding cycles to ensure that all HCA contents have arrived at one of the other bleeders.

Your ultimate fix will be of interest!

 

[NoTempoLimit]

Major PITA!!...
...Your ultimate fix will be of interest!

Thanks for posting with the links. I'll read up on those threads.

I've been able to continue driving no no problems and improved damping. But I do want to fix this properly.