Quick question; wouldn't it be better to fill the globes with fluid just prior to fitting ?
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There is no space to fill the globes with fluid until they are pressurized.Quick question; wouldn't it be better to fill the globes with fluid just prior to fitting ?
Yup! No point trying to fill them with a few drops. There's not much room in there. And any air will come out during bleeding anyway.There is no space to fill the globes with fluid until they are pressurized.
I lit up the reservoir like a light bulb from the side, can see any fluid, however the AHC light is not on, which is odd. Also the reason I am down this road is for the past few weeks, the rear end drops rapidly after I get off the freeway, only after driving on the freeway, usually at the stop light at the end of the ramp, within a minute or so.
I used the procedure linked at the bottom of my post.Very interesting post; you did a fluid change prior to this you said and I was wondering if you could run through what you did ? I have a 4.5 v8 diesel which I think in UK spec suspension wise the same as US LX570 (?). The 4x bleeds front/rear are obvious but I'm struggling with the main accumulator bleed in terms of finding it and/or bleeding it.
I've pasted two pages from the service briefing I have below; I'm assuming the main accumulator bleed is the Suspension Control Pump Accumulator Assembly in the two diagrams. There is also a bit in the text about how the L-N N-H shift uses fluid from the SCPAacc only if its at pressure. I'm guessing this is important when doing a fluid flush as there must be a lot of fluid in there ?
I've also attached the service pdf. No idea where I got it from but its quite a useful document on AHC and KDS.
Thanks, sorry to be a pain but better to ask !
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It can cause low pressure sensors to trip, disabling the pump. Which then needs to be manually run via techstream. This is why the dealers don’t bleed it as part of their normal procedures. Multiple bleeds of the other 4 accomplish the same thing without the additional hassleWhy not bleed the 5th?
After only bleeding the 4 my truck's suspension felt terrible. I did the 5th and it made a huge difference.
Ok, you got an actual “HA!” out of me.(Bad) LX joke:
Customer: When was the last AHC service done?
Dealer: Good question....I bleed the fifth.
[/QUOTE]Thinking about this a bit having done the flush as to exactly which route the fluid takes as you bleed the system. I was wondering how much old fluid remains after the process.
There is a case for saying that you are better to have the car in L as the Levelling Valve remains closed when the ECU signal isn't received to raise or lower the car and the closed parts of the system (shocks and front relief chambers) are as empty as it is possible to be.
Bleeding at the front Damping Force Control Actuators on both sides the fluid that comes out is coming front the two front shocks and from the two Relief Gas Chambers on both sides. The Levelling Valve is shut so no fluid can come via the Height Control Valve or the rest of the system. ( the front drops slower while bleeding than the rear which doesn't have the Relief Chambers. I noticed that most of the old fluid came from the first front bleed as both sides are linked via the Height Control Valve and having raised the car back to L-N-L before doing the second front very little old fluid came out of the second front bleed which makes sense.)
Having bled the front or rear bleeds the fluid then comes via the Levelling Value when the ECU allows it to open as you start the car. Going from on the stops to L refills the Relief Gas Chambers and front or rear Shocks; then going from L to N discharges the fluid within the Suspension Control Pump Ass ( it was noticeable that the front took a lot longer to lift after bleeding than the back did which again makes sense as its filing not only the shocks but also the two large relief chambers which will have completely discharged their pressure as they are nitrogen filled accumulators as well)
The rear No.1 Gas Chambers are directly attached to the shocks with no relief chambers so they bleed out less fluid and the back drops very quickly when this fluid is released.
In effect the bleed fluid only comes from the shocks and front relief gas chambers so while the rest of the system is completely purged with new fluid, when the levelling valve opens as you start the car and engage the pump to replace the lost fluid, the shocks and chambers are really only rinsed as some old fluid will remain as they are a closed system. Quite how many "rinses" you need is anyone's guess but from what I observed one rinse seemed to remove the vast majority of the fluid.
I can also see one major possible cock up in this. If you had raised the car from L-N and then switched off the car before the pump had been able to recharge the Suspension Control Pump Acc Ass completely THEN bled the shocks you are then completely reliant on the pump to not only recharge the SCPAA but also the two front relief chambers and the shocks (which is a big ask) and will take some time. It can take up to 14 seconds to raise the car with a charged system, with a completely discharged system it could take far longer. I have read posts from people who got ECU errors during the process and this might be a possible reason why.
I hope this makes sense and its very much in line with your notes which have been very helpful; I'm sure I've missed something !
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I think I spilled almost a full liter between pump testing and bleeding.Just try not to spill too much of that fluid. It sticks on everything.