Changing out the AHC suspension fluid?

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While going from high to low or visa versa, are there supposed to be air bubbles that release into the reservoir tank right as the pump stops running? I cycled the ahc system between low and high at least 4 times with this still happening even though everything seems to be working fine.
 
TexLexican said:
While going from high to low or visa versa, are there supposed to be air bubbles that release into the reservoir tank right as the pump stops running? I cycled the ahc system between low and high at least 4 times with this still happening even though everything seems to be working fine.
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Not air bubbles, but there is a little squirt of released pressure each time the pump stops.
 
Did an AHC fluid refresh on my 06LX yesterday. Used up all 2.5L AHC fluid in the can and level in the reservoir is right at “Max”. This is after I bled all 4 bleeder valve and new pink AHC fluid came out.
IMG_7942.jpeg
 
hoser said:
Welcome uHu! Nice to see more and more non-US members. I'm always interested in the differences in models.

As for the AHC fluid, I'm not sure what to tell you but I'll ramble some thoughts. I would have guessed brake fluid to be very similiar to the AHC fluid since they both work at high pressure and temperature. Brake fluid is not "spongy" at all but the brake system can get spongy when there is air in the system.

Have you tried to bleed your actuators and accumulator? When you bleed the system, the suspension compresses completely to the bumpstops. So what's left is the remaining fluid in the shock and the line that goes from the shocks to the actuators. Of course, the only way to get ALL of the brake fluid out would be to remove the shocks/brake lines and bleed them out. But if you were to flush the system out say 2-3 times waiting a couple days between flushes, I would think you'd be able to get 95% or more of the brake fluid out.

Perhaps, one or more of your actuators have gone bad and that is the real cause of your AHC failure? How does the ride feel?

Edit: Do NOT use brake fluid in the AHC system. It will deteriorate the rubber membrane. This Motul fluid is probably closer to what Toyota/Lexus sells but for the price, why not just use OEM stuff.
http://www.motul.com.au/product_line_up/fork_brake_others/others20.html
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Hi guys having recently worked on a very trying AHC failure problem, during my investigations I came to understand that when the Damping force accumulators (Globes) are bled until New oil has come through and until the vehicle is almost down on bump stops, the Shocks or Hydraulic struts are essentially empty of oil at that point. The only (old oil ) left is in the pipe between that Globes and the top of the Shock. This is a conundrum as when you start the vehicle to “reset” to (N) the old oil (in the pipe) between that Globes and the top of that shock, will be the first oil pushed back into that shock. I would not like to comment too much upon how to deal with that problem as it probably means needing to open the pipe at top of shock and using the New Oil in the system to push that trapped oil in the pipe, out, thus allowing only new oil to get through to the top of the shock.

But this is a technical challenge as if you were to open the pipe at top of shock the system pressure sensors would activate and place the AHC into an immobilised state, thus needing to go through an AHC reset procedure.

I personally don’t think it is worth worrying about that residual oil in those pipes as the quality of “ride” is more determined by the oil quality going into the Globes, which will now be New AHC oil after this replenishing. I also personally don’t think the Brake Fluid would have ever got as far as getting past the globes towards the shocks in the first place.

However essentially for “understanding” purposes my point is in reference to how those Shocks or Hydraulic Struts work, when those shocks are fully lowered, there is basically no oil left in there.
 
Urtwob said:
Hi guys having recently worked on a very trying AHC failure problem, during my investigations I came to understand that when the Damping force accumulators (Globes) are bled until New oil has come through and until the vehicle is almost down on bump stops, the Shocks or Hydraulic struts are essentially empty of oil at that point. The only (old oil ) left is in the pipe between that Globes and the top of the Shock. This is a conundrum as when you start the vehicle to “reset” to (N) the old oil (in the pipe) between that Globes and the top of that shock, will be the first oil pushed back into that shock. I would not like to comment too much upon how to deal with that problem as it probably means needing to open the pipe at top of shock and using the New Oil in the system to push that trapped oil in the pipe, out, thus allowing only new oil to get through to the top of the shock.

But this is a technical challenge as if you were to open the pipe at top of shock the system pressure sensors would activate and place the AHC into an immobilised state, thus needing to go through an AHC reset procedure.

I personally don’t think it is worth worrying about that residual oil in those pipes as the quality of “ride” is more determined by the oil quality going into the Globes, which will now be New AHC oil after this replenishing. I also personally don’t think the Brake Fluid would have ever got as far as getting past the globes towards the shocks in the first place.

However essentially for “understanding” purposes my point is in reference to how those Shocks or Hydraulic Struts work, when those shocks are fully lowered, there is basically no oil left in there.
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If you flush the system enough from the globe even the residual fluid in the struts will be new.
 
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