AHC Globe replacement-air in height control accumulator?! (1 Viewer)

[Rio Sunset]

Replaced all four accumulators.

Emptied and filled reservoir, bled four corners and the height accumulator, until fluid stopped, installed globes, then bled air at the four corners, but not the height accumulator.

Should I have also bled "air" from the height control accumulator?

It now takes 30 seconds to raise from low to high...

Otherwise handles excellent. Pressures look good. All damping modes work etc.

Pressures

6.9MPA front
6.0MPA rear
10MPA height accumulator

 

[Rio Sunset]

I followed Paddo's instructions below.

They state that the 4 corners should be bled after the change. No mention of the height accumulator after the initial bleed.

Here's something I’ve provided to others:

I've done the changeouts two ways: combined with a full bleed and fluid replacement and I've tried a "low fluid loss method". You could probably combine both methods too. Have you got your 36mm ford fan clutch wrench from auto zone and a spare can of fluid?
Method 1. Last globe changeout I did I dropped it to L, engine OFF, bleed all 5 bleeders down to the point where fluid stops flowing (total about 1 liter) so the truck is sitting on the bump stops and then sucked out the reservoir and dumped in a full can of fresh fluid as per my quick and easy 1 can method. So you've got truck on bumps, no pressure behind any globes and a full reservoir. Unscrew old and replace the new globes, you can try and put a bit of fresh fluid in the throats of each globe but it just spills out really, but do wet the O ring with fluid. There is some spec for globe tightness but I just tighten them up and give them a bit of a nudge. After all the fan clutch wrench is 13 or 14 in long so you've got plenty of leverage there. I guess I tighten them to maybe 40 ft lbs? So when you've done the four globes start her up and it will recharge everything and then raise her to N. The fluid level in the reservoir should be a bit above max. Turn her OFF and give each corner a quick bleed, just an ounce or three till there are no bubbles. Start her up again and confirm the fluid level is good, if the level is a bit over max is ok too and you're done.
The other low fluid loss way I've done it is:
Vehicle off, at N height and jacked up the front so both front wheels are off the ground. Crack a front bleeder to relieve pressure (both sides will depressurize as they are hydraulically connected) then spin off/spin on the new globe after wetting the o ring with fluid. Move over to the other side and repeat, crack the bleeder just to make sure there is no pressure but it'll be fine. Tighten the front up, drop her back on the ground and then do the back the same way, both wheels off the ground, relieve pressure and spin off/spin on the new. Keep approximate track of just how much fluid you've drained at each corner and add that much fresh back into the reservoir, plus a cup or two for bleeding each corner. You won't bleed that much out with the wheels off the ground and the shock actuators at full extension. On the ground start her up and give each corner a bleed till no bubbles. I try and keep track of how much I'm bleeding out so I don't run the risk off getting too low in the reservoir. A quick confirmation check bleed at the height accumulator is probably worth it too. Hope this helps.

 

[Clunky]

What type of accumulator did you go with? OEM?

 

[Rio Sunset]

Yes. OEM. Fronts were bad, rears were good. Replaced all four.

 

[DirtDawg]

Any time you open the system in multiple points I’d bleed the whole system.

 

[PADDO]

Replaced all four accumulators.

Emptied and filled reservoir, bled four corners and the height accumulator, until fluid stopped, installed globes, then bled air at the four corners, but not the height accumulator.

Should I have also bled "air" from the height control accumulator?

It now takes 30 seconds to raise from low to high...

Otherwise handles excellent. Pressures look good. All damping modes work etc.

Pressures

6.9MPA front
6.0MPA rear
10MPA height accumulator

I’ve never got any air out of the height accumulator after changing globes but knock yourself out and give it a bleed if you want. Taking 30 seconds to go from L to H is in line with system performance tolerances that say 10-15 secs from L to N and 10-15 from N to H *with a charged height accumulator. Going from L to H in one fell swoop discharges the height accumulator and therefore to finish the raise cycle you have only pump output that’s not augmented by the height accumulator. Adds time to the cycle.
Also, the kicker here is that the system will be slower with new accumulators (full nitrogen charges) as opposed to flat/blown accumulators because the new ones divert more flow from the pump as the vehicle raises and the system neutral pressures increase and force fluid into the accumulators. For example: if you removed your 4 damper accumulators and blanked their ports and did a L to H raise then 100% of the pump output would go to the shock actuators and the vehicle would raise quite quickly. Other extreme: put large bladders in place of the damper accumulators and raise fronm L to H and you’d find 100% of the pump output would take the path of least resistance and fill the expandable bladders, height wouldn’t change and you’d just run out of fluid if you didn’t have an infinite supply. Two extreme examples to try and point out how the system responds to a flat accumulator v a fully charged one. So in your case the additional raise time is a function of fluid compressing your new accumulators and raising the vehicle with a little pump that has a fixed output. All good .

 

[Rio Sunset]

Perfect, thanks! Drives like a Mercedes now!

 

[Rio Sunset]

Update- Takes 20-30 seconds to raise from L-N
Also 20-30 seconds from N-H

Pressure at height accumulator is good.

Should I jack up the front end and raise from L-H to "fill'" the accumulator?

If I open the bleeder on the height accumulator to measure its contents, should the vehicle be in L mode? What do I need to do to purge air after emptying the height accumulator?

Are their any real consequences to driving with a failed eight accumulator/and or weak pump other than slow raising and lowering?

 

[PADDO]

Time the raise cycles, is 20-30 secs a guess?
Do not jack the front to “fill” the height accumulator - dangerous and pointless. The ECU commands the height accumulator solenoid to open so it can discharge its pressurized contents in conjunction with a raise command when speed is less than 16mph. Raising wheels and running the AHC isn’t necessary or smart.
After a raise cycle is completed in a normally functioning system the height accumulator will then be re charged by the pump, it might take 10-20 or so seconds after the height indicator lights have transitioned for the pump to finish and you should hear the height accumulator solenoid lightly clunking on completion. Is that what you’re taking as the time to raise? You can monitor the valves involved during a raise, the leveling and height accumulator, via Techstream. You can also independently test them.
It doesn’t make any difference from what height you measure the height accumulator’s content as long as it’s charged. Make it easy for yourself and raise from L to N wait a minute with engine running, turn off the engine and then check it. When bleeding the height accumulator contents off close the bleeder as fluid stops flowing as observed in the clear tube you’re using. No need to purge or anything as it’s a sealed system and will recharge from the pump if working properly. Fluid is pumped in under pressure, stored then discharged to the front and rear circuits during a raise/level. That’s all it does so any bulk air in it for whatever reason will be pushed through the system.

 

[JPS]

Also, the kicker here is that the system will be slower with new accumulators (full nitrogen charges) as opposed to flat/blown accumulators because the new ones divert more flow from the pump as the vehicle raises and the system neutral pressures increase and force fluid into the accumulators. For example: if you removed your 4 damper accumulators and blanked their ports and did a L to H raise then 100% of the pump output would go to the shock actuators and the vehicle would raise quite quickly. Other extreme: put large bladders in place of the damper accumulators and raise fronm L to H and you’d find 100% of the pump output would take the path of least resistance and fill the expandable bladders, height wouldn’t change and you’d just run out of fluid if you didn’t have an infinite supply. Two extreme examples to try and point out how the system responds to a flat accumulator v a fully charged one. So in your case the additional raise time is a function of fluid compressing your new accumulators and raising the vehicle with a little pump that has a fixed output. All good .

I noticed also that the system takes a little longer after the new accumulators. It raised very quickly, but unevenly on the blown accumulators, but more smoother and evenly now with the new ones.

 

[2001LC]

36MM wrench issue. What is a good one for the globes?
Anyone know?
One I can get in a store this morning.

I picked-up (rental) a new kit from Advance Auto, with 36mm in it. It is a Powerbuilt for fan clutch kit with ~4 various wrenches in it. I got the first glode off then on. As I went for second, which seem tighter. The wrench slipped/spun around nut. I measure the 36mm span on the wrench, and it had widen to ~39mm under the force of use. JUNK. I use my visa to compress back to 36mm, but metal is now to weak, widens even with lite force of use.

 

[trdcorolla]

36MM wrench issue. What is a good one for the globes?
Anyone know?
One I can get in a store this morning.

I picked-up (rental) a new kit from Advance Auto, with 36mm in it. It is a Powerbuilt for fan clutch kit with ~4 various wrenches in it. I got the first glode off then on. As I went for second, which seem tighter. The wrench slipped/spun around nut. I measure the 36mm span on the wrench, and it had widen to ~39mm under the force of use. JUNK. I use my visa to compress back to 36mm, but metal is now to weak, widens even with lite force of use.

I had the same problem as you when I replaced my globes with my "rented" fan clutch set. I borrowed a grinded down 36mm wrench and a 10"ish cheater pipe from a mechanic friend that he uses on BMW's.

 

[2001LC]

Thanks!

Yeah I've ground down a wrench before. NAPA will have a 36MM opened polished wrench for me this afternoon. I'll likely need to grind down. Meantime I pick-up a HF set and and ACE plumbers tool, to test out.