replacing AHC globes/accumulators (8 Viewers)

[flintknapper]

Tell me if the symptoms I am having are what you experienced before you swapped the globes and if it was improved after.

Lately, it feels like every little bump causes a jarring sensation in the vehicle. Big speed bumps are OK, but little cracks in the road are very pronounced. I don't know how much of this the globes vs the E-rated tires.

The vehicle goes up and down fine. The comfort switch works.

I get 7 marks on the test. I have bled and replaced the AHC fluid twice in the last 20k miles.

For the best ride and least amount of 'road transfer': In addition to changing out failed globes, springs, flushing the system and adjusting front and rear pressures, you should also inspect all of your rubber bushings (I.E. shocks, sway bars, body mounts, etc...) they are the final link between the suspension and the chassis/body.

 

[JPS]

Finished my 4 accumulator swap this weekend. All but one rear globe was completely shot.... 2005 stickered globes with 175k on them.. surprised that one was still functional, or at least still had some type of interior body.

I had done the bleed procedure about 6 months prior and the LX rode great for about 2 days after the bleed, which sunrises me now that I see how bad of shape the globes were in. The first time I bled the globes, all I bled out was dark disgusting AHC fluid. This time I got back "foamy", tan colored AHC fluid. I'm assuming this was caused by air? I was very careful once the change and bleed was complete to make sure no air was crawling its way back into the system once I got clear AHC return fluid.

That being said I did do a graduation test prior to starting and got a 4. After the globe change I stopped counting at 13. To change out all four cost me $1100.

The ride is now once again amazing.

 

[CanadianRockyCruiser]

Finished my 4 accumulator swap this weekend. All but one rear globe was completely shot.... 2005 stickered globes with 175k on them.. surprised that one was still functional, or at least still had some type of interior body.

I had done the bleed procedure about 6 months prior and the LX rode great for about 2 days after the bleed, which sunrises me now that I see how bad of shape the globes were in. The first time I bled the globes, all I bled out was dark disgusting AHC fluid. This time I got back "foamy", tan colored AHC fluid. I'm assuming this was caused by air? I was very careful once the change and bleed was complete to make sure no air was crawling its way back into the system once I got clear AHC return fluid.

That being said I did do a graduation test prior to starting and got a 4. After the globe change I stopped counting at 13. To change out all four cost me $1100.

The ride is now once again amazing.

Where did you buy your globes? Thanks!

 

[JPS]

Where did you buy your globes? Thanks!

I got mine from a vendor on Ebay "fastpartshipping". I got them based off of reputation on over 13,000 transactions, and the fact that he claimed the accumulators were " are fresh stock made around july/august 2017" . He was also knowledgeable about the process. I have about 100 miles or so on the new ones and am happy so far.

 

[CanadianRockyCruiser]

I got mine from a vendor on Ebay "fastpartshipping". I got them based off of reputation on over 13,000 transactions, and the fact that he claimed the accumulators were " are fresh stock made around july/august 2017" . He was also knowledgeable about the process. I have about 100 miles or so on the new ones and am happy so far.

Thanks!

 

[Qtonic]

If you follow that you can’t get caught with insufficient fluid in the reservoir and the issues that then presents.

Can you elaborate on the issues this presents? I think this happened to me. Is the solution just to redo the entire flush, or is it more involved? Incidentally, I may have introduced air into my accumulator as well from failing to fully close the bleeder.

(Long explanation of my problem here for reference if you're interested: Bit of a setback when flushing AHC. Hoping for some advice.)

Thanks for all the info you've provided on the topic.

 

[PADDO]

Can you elaborate on the issues this presents? I think this happened to me. Is the solution just to redo the entire flush, or is it more involved? Incidentally, I may have introduced air into my accumulator as well from failing to fully close the bleeder.

(Long explanation of my problem here for reference if you're interested: Bit of a setback when flushing AHC. Hoping for some advice.)

Thanks for all the info you've provided on the topic.

Sounds like you’ve been having some fun . You’re most likely fine; if the pump didn’t draw air and loose it’s prime then that’s ok and if any air entered the open bleeder in the height accumulator it would be a trivial amount not worth loosing sleep over. I’ve replaced bleeders on depressurized system with no detectable air entering - it’s not as if there is a vacuum drawing it in or anything. The bleeders are the same design as the brake bleeders and they completely unscrew but you really only need to crack them open 1/2 turn. From your other post re damper globe health you get a generalized idea by the L to H test and the 16 step damper test. You don’t need Techstream for these two checks. So if your fluid level is above Min with engine running at N height, it raises and lowers with no OFF light I’d say your ok to do your other checks and pressure readings. If you do change out the damper accumulators then this can be done without loosing very much fluid by jacking the wheels off the ground.

 

[Qtonic]

...if any air entered the open bleeder in the height accumulator it would be a trivial amount not worth loosing sleep over. I’ve replaced bleeders on depressurized system with no detectable air entering - it’s not as if there is a vacuum drawing it in or anything.

That's good to know about the height accumulator and the fact that it isn't under vacuum. Thanks for your explanation.

My next concern is the very low level reached in the reservoir. Immediately after the fluid loss the level was quite low, but should have been fine. I also added what was left in the third bottle (~300ml). But when starting up again it leveled itself and drew it back down near the bottom. Unfortunately I then had to drive a short distance, including going up and down an incline. I really don't know if it ingested any air at that point. At the moment, the reservoir is very low. I can see parts of the bottom plastic. Putting it in low would add some, but I haven't stated it since.

Any tips how to proceed? I'm getting new fluid tomorrow. I'm debating whether to fill to the proper level and see how it performs, including on the grad test, or go ahead and do the full fluid replacement cycle again. Thanks.

 

[PADDO]

From your description I think you’re still ok. The pump doesn’t run continuously so it sounds like after you did your top up with the 300ml and it drew down to recharge you still had just enough. I’d just add fluid when you can to between Max and Min when running at N height and go about your day. You won’t have bulk air in the system as if you’d replaced a shock actuator without priming it with fluid, and a few little bubbles won’t really affect anything - all hydraulic systems (unless operated under negative pressure) have air bubbles that naturally come out of solution from the oil. And even then, if the pump did become airlocked and faulted out you just jump start the system with a paper clip in DTC1 and re bleed.

 

[dwh13]

I’m in the middle of pulling my old globes to replace them (ordered the Pleiades set). I got the 36 mm Ford fan clutch wrench which popped the passenger side globes off no problem. But no amount of penetrating fluid, fan clutch wrench or strap wrench will make the two on the driver’s side so much as budge. I even lined a strap wrench with coarse sandpaper - no dice. Anything else I should try?

 

[flintknapper]

Edited: For safety's sake.

Suggest any 'Quotes' be edited/deleted as well.

I sometimes forget no matter how obvious a procedure might be (depressurize systems before working on them, turn off engine before removing serpentine belt, etc...) there will always be someone who will get themselves into trouble.

In that interest, I have deleted my admittedly poor suggestion.

With thanks to those contributing information regarding certain safety concerns.



Flint.

 

[dwh13]

^^^^^^^^^

If you don't plan on keeping them (and I don't know why you would)...then treat them just like an oil filter that won't budge.

DRILL THEM. All the way through at the strongest point of the globe. Insert a long, sturdy screwdriver or something similar through it. Then use the 36mm and the screwdriver at the same time to get added leverage.

You 'might' be able to the same thing with your strap wrench and 36mm, but I wouldn't count on it.

I’m pretty sure I’ve rounded the bolt at this point. I’ll try drilling, but I don’t think any of my drills are powerful enough; these globes are heavy duty stuff.

 

[PADDO]

I’m pretty sure I’ve rounded the bolt at this point. I’ll try drilling, but I don’t think any of my drills are powerful enough; these globes are heavy duty stuff.

Wear good quality eye protection if you’re going to drill into a charged accumulator.
Not something I’d do lightly!

Edited for extra safety details.

Damper globes (accumulators) are charged with nitrogen and are pressurized to the order of 325psi. Whilst fitted to the vehicle the AHC systems static pressure is actually supporting the vehicle, holding it up, this static hydraulic pressure is in the order of 800-900 psi. The accumulators assume the same static pressure as the rest of the system (800-900psi) and this is the pressure that is behind any activity like drilling into a pressurized component or disconnecting a flexible line to a shock actuator. Breaching the hydraulic systems integrity whilst it’s pressurized by drilling for example will cause it’s immediate depressurization with fluid and swarf being violently expelled and the vehicles height dropping down to the front or rear bump stops. Prior to removing any pressurized component the systems static pressure must be lowered by opening the bleed points and allowing the static pressure to discharge and the vehicle will lower in a controlled manner unless it’s supported. It must be borne in mind that even after the AHC hydraulic static pressure has been bleed off the individual globes and height accumulator still retain their gas charges (~325 and 850psi respectively) and successfully puncturing them via drilling will result in swarf/gas being violently expelled which may result in injury.

 

[dwh13]

Wear good quality eye protection if you’re going to drill into a charged accumulator.
Not something I’d do lightly!

Good point. I couldn’t get more than a millimeter or so through anyway. Any other thoughts before I have my Indy shop fix it tomorrow?

 

[PADDO]

Try a cold chisel. For God’s sake do not drill into charged accumulators unless you’re ready and prepared for a very sudden depressurization of the globe at a minimum, or the whole system if it’s not on the bump stops or jack stands. I hope you’ve bleed off residual hydraulic pressure and/or have supported the vehicle because whilst at N height you’ve got about 800-900 psi of hydraulic pressure in the system thats holding the vehicle up that will want to drop to atmospheric pressure really really quickly.

 

[Mark WV]

yes, a simple hammer and sharp chisel is the way to go - just aim the chisel on the widest part of the globe and they will simply unscrew by hand once you get the rotation started with after a few good whacks in a counter-clockwise direction.

I just want to add for safety's sake that you need to Bleed down the pressure on all four actuators until nothing else comes out the bleed nipple. I failed to adequately bleed off the pressure and while unscrewing one of the rear globes, it shot loose with a bang and sprayed fluid 20 feet across the garage. good thing my hand was on the side of the globe, as it would have easily broken / crushed my hand when it popped off.

These things are under extreme pressure - DON'T DRILL THEM

 

[dwh13]

yes, a simple hammer and sharp chisel is the way to go - just aim the chisel on the widest part of the globe and they will simply unscrew by hand once you get the rotation started with after a few good whacks in a counter-clockwise direction.

I just want to add for safety's sake that you need to Bleed down the pressure on all four actuators until nothing else comes out the bleed nipple. I failed to adequately bleed off the pressure and while unscrewing one of the rear globes, it shot loose with a bang and sprayed fluid 20 feet across the garage. good thing my hand was on the side of the globe, as it would have easily broken / crushed my hand when it popped off.

These things are under extreme pressure - DON'T DRILL THEM

Thanks a million to both of you - I got a cold chisel and a sledgehammer and had them off in 5 minutes, no problem! Now if only my parts would get here, and not be lost in the mail in England somewhere...

 

[NC-Grayson]

I'm trying to remove mine as well. after 3 rentals of auto parts store's 36mm fan clutch wrenches that were all mangled and wide out of spec, I ordered one from amazon. I've been soaking in PB for a week now, so hopefully this new wrench does the trick. Glad to know I have options otherwise!

 

[dwh13]

I'm trying to remove mine as well. after 3 rentals of auto parts store's 36mm fan clutch wrenches that were all mangled and wide out of spec, I ordered one from amazon. I've been soaking in PB for a week now, so hopefully this new wrench does the trick. Glad to know I have options otherwise!

I’m pretty sure the one I rented from Pep Boys was out of spec as well - a good bit of play around the bolt head which caused it to round off. I vote on chisel + hammer being the new de facto method of removing globes.

 

[Mark WV]

just a few notes on when I changed out the globes on my 06 cruiser:
My suspension on the front was like it had no springs at all - made driving on two lane roads tough although interstate driving wasn't too bad.

I bled all four four corners twice with 2 cans of ahc fluid but got nothing but foam - I assumed this was from a ruptured diaphragm in one or more of the globes which released the nitrogen charge into the fluid. (and continued to release more nitrogen as I bled the old fluid out)

even after bleeding I only had a 5 graduation change on the reservoir from low to high

I replaced all four globes while following several of the threads here on Mud for change-out and bleeding. Rides like new now! Thanks to all on Mud who take the time to post and provide their technical knowledge !

here is a photo of one of the old globes I sliced open - Note the rubber diaphragm which separates the nitrogen charge from the ahc fluid. What may not be evident from the photo is that the rubber layers have de-laminated and apparently had failed. Also note the thickness of the globe walls - as stated by several above, these things hold a LOT of pressure....