Arggghhh. each question raises another one. 
When cranking the torsion bars, would it have effect on your articulation?
When cranking the torsion bars, would it have effect on your articulation?
AHC Fluid Change How To -- Need Input (4 Viewers)
- Thread starter ntsaint
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As we are living in a metric world, it is 43,000 kilometers, which is in your terminology 26,718 miles and 1691.7 yards.
uHu
Bridgeburner
Cranking torsion bars changes nothing but the AHC pressure. It will only change the balance between the load carried by the steel-spring and the and the load on the gas-spring.
Changing the fluid doesn't do anything to pressures or heights, but it might make it easier for the fluid to flow through the valves in a controlled way.
The height is easy to check and adjust. See attached pdf.
The pressure up front is easy to adjust.
The rear pressure is hard to change without changing the coil spring, but if it's not too far out, you could still test the spheres.
I bled and re-filled my ACH system last night. Everything went well and the truck rides great today. The instructions in this thread were spot-on.
I did have three questions:
1) What does the accumulator actually do as part of the AHC system?
2) Is it ok to bleed the accumulator after the individual actuators?
3) Is it normal for the accumulator to stop draining completely after one bleed and then not re-fill after cycling the pump?
I did have three questions:
1) What does the accumulator actually do as part of the AHC system?
2) Is it ok to bleed the accumulator after the individual actuators?
3) Is it normal for the accumulator to stop draining completely after one bleed and then not re-fill after cycling the pump?
uHu
Bridgeburner
1: The cylindrical accumulator stores (accumulates) pressurized hydraulic oil for rapid, small changes in height (= pressure in the spheres).
2: It's OK
3: It's normal that when bleeding the accumulator, the flow stops abruptly. The pressure will not build up again until the ahc ecu finds out that it "has time/capacity to do it" - normally after doing a full LO/HI/NORMAL cycle, or simply after the next normal adjustment because of changes in the load.
Awesome. Thanks for the quick response.
I will post my experience for the sake of adding to this thread:
Haviing bled brakes my whole life, I instinctually started with the bleeder valve farthest from the reservoir (driver's side rear) and move closer and moved towards the reservoir (dr rear, pass. rear, accumulator, driver's front, pass. front). As expected, the first actuator took the longest to get new fluid. I ran about 24 ounces through it before it cleared up. The rest of the actuators came clear in 12 ounces or less. The accumulator only had about 10 ounces in it. Once it was dry, it stayed dry even after cycling the pump (while parked on level ground).
My LX has 70k miles and was previously owned by a very nice old lady who informed me that she had never used the AHC system in her 7 years of ownership. The old fluid that came out actually looked pretty good. The first few ounces at each corner was a bit dark and had some froth to it, but the remainder was still mostly clear and red. I am happy to have serviced it as it gives me peace of mind.
The total job took me about an hour and a half (being very methodical and cleaning up everything as I went) and cost me about $70 for two jugs of AHC fluid.
uHu
Bridgeburner
Comment: The AHC is being used all the time. It's an automatic leveling system - doing it's job without user input. I guess she's saying that she never pushed the buttons.
Planning on flushing mine today. After reading the full thread and the pdf instructions, a couple things are unclear to me (probably being dense)...
1) It seems everyone is bleeding from the Neutral position. Why not bleed from the High position? Would that give less bleeding cycles?
2) I see where the 4 actuators are. But where is the accumulator?
Many Thanks!!
Skip
1) It seems everyone is bleeding from the Neutral position. Why not bleed from the High position? Would that give less bleeding cycles?
2) I see where the 4 actuators are. But where is the accumulator?
Many Thanks!!
Skip
As far as why not bleed from the High position, I don't know, Maybe too high pressure... I just did mine from N position and got new fluid out each accumulator within probably 2 to 3 bleeding cycles, so it's really not too time consuming. The accumulators are what actually provide the damping in the system. There two located on either side of the truck, tucked under the rockers, one for each wheel. There is also a cylindrical shaped thing located on the driver side between the accumulators, sorry, I'm not sure what to call it, but you also need to bleed that. It will help get additional old fluid out of the system. Other than reading posts on here, I had never done this before and it took me a little over an hour. I did more bleeding than I needed to do simply because I had extra fluid, so it really shouldn't be too bad. Good luck.
Maybe I am calling the actuators accumulators by mistake...at any rate, I'm guessing what you are asking about as the accumulator is the cylinder looking thing b/t the two actuators on the driver side.
Thanks.
Either way, I found all 5. Really, kinda obvious once I knew what to look for.
Thanks again!!
The fluid that came out of my reservoir sure is nasty looking and smelling stuff...
Either way, I found all 5. Really, kinda obvious once I knew what to look for.
Thanks again!!
The fluid that came out of my reservoir sure is nasty looking and smelling stuff...
In Toyota-speak, the globes are called "Damping Force Actuators".
The "Accumlator" is the thing with a tubular tank aft of the front DFA on the driver's side frame rail...there's only one.
Terms per my Lexus '01 FSM.
hth
Steve
Well I'm "finished".
Of course, once done, I put into the high position and checked the level. I either pulled air into the system or "all but" did.
I'll probably order some more fluid and do it again.
Is there a way to tell if there's air in there? Damage occur if I drive it like this?
Bummed.
Thanks,
Skip
Of course, once done, I put into the high position and checked the level. I either pulled air into the system or "all but" did.
I'll probably order some more fluid and do it again.
Is there a way to tell if there's air in there? Damage occur if I drive it like this?
Bummed.
Thanks,
Skip
If everything is functioning normally and you don't have a flashing AHC light you most likely didn't draw air in. Only real way to know, in the absence of the pump getting an air lock and not making pressure which will cause it to enter fail safe and flash the AHC light, is to check for air at the bleed points again. If you do get a bit of air out of a bleed point that's not a huge deal and won't hurt anything. That's why we have bleed points; to drain fluid and purge the system. Ideally you want to set your fluid height at the max mark when you're at N and done bleeding, never let it go below min or you risk drawing air in.
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Thanks. That's reassuring.
I drove it for a bit this afternoon. I could not notice anything wrong.
Maybe I (for once) got lucky???
I drove it for a bit this afternoon. I could not notice anything wrong.
Maybe I (for once) got lucky???
This is my to do list as well.
It hasn't been done since I have the car.
It hasn't been done since I have the car.
uHu
Bridgeburner
The "globes", or "gas springs", or "spheres", are screwed on to the Actuators.
The tyota litterature only calls the cylindrical, piston type accumulator an Accumulator; while the other 4 spherical, membrane type accumulators are called Nitrogen Spheres or Globes, and are the actual gas springs of the system.
The cylindrical accumulator stores pressure for faster adjustment of the ahc system, much like the accumulator of the braking system.
There is no problem with bleeding from High. You get more out in one go.
It is good to do more than one bleeding, with some driving in between, in order to get out (or dilute) more of what is inside the shocks.
Great info. Thanks.
