AHC Fluid Change How To -- Need Input (2 Viewers)

[PADDO]

I wouldn’t worry about anything. A temporary low fluid level in the reservoir during a maintenance activity isn’t that bad as the pump is below the reservoir and it’s normally immersed in fluid within its housing, so if you could see some fluid in the reservoir then the pump was wet. Obviously you’d not want to drive around and cycle the system with a very low fluid level though. If you follow my quick and easy fluid change procedure you won’t get caught out with a low fluid level .

 

[lcdude]

I wouldn’t worry about anything. A temporary low fluid level in the reservoir during a maintenance activity isn’t that bad as the pump is below the reservoir and it’s normally immersed in fluid within its housing, so if you could see some fluid in the reservoir then the pump was wet. Obviously you’d not want to drive around and cycle the system with a very low fluid level though. If you follow my quick and easy fluid change procedure you won’t get caught out with a low fluid level .

Thanks! Was doing my best to follow your procedure. The mistake I made was not to look into the reservoir for fluid level and just relied on what I could see from the outside markings.

My original concern was that my reservoir could have been empty for few seconds until I realized my mistake, turned the truck off and refilled the reservoir. I assume the truck still cycling thru L-N-H modes means I did not impact the pump or anything else, correct?

 

[PADDO]

Thanks! Was doing my best to follow your procedure. The mistake I made was not to look into the reservoir for fluid level and just relied on what I could see from the outside markings.

My original concern was that my reservoir could have been empty for few seconds until I realized my mistake, turned the truck off and refilled the reservoir. I assume the truck still cycling thru L-N-H modes means I did not impact the pump or anything else, correct?

Correct, you’ve got normal operation with a functioning pump. It’s not likely any air made it’s way into the system.

 

[128keaton]

Just to confirm, I need to order 3 of the 1L bottles? (As per PADDO's instructions?)

 

[lcdude]

Correct. I used almost all 3 given I lost a little while bleeding to ensure pink fluid comes out.

 

[128keaton]

Correct. I used almost all 3 given I lost a little while bleeding to ensure pink fluid comes out.

Thank you. Hoping this brings back some better dampening over potholes.

 

[lcdude]

Thank you. Hoping this brings back some better dampening over potholes.

I experienced a noticeable change. Plus brought the required lubrication into the hydrolic system, which is good as well.

 

[128keaton]

I experienced a noticeable change. Plus brought the required lubrication into the hydrolic system, which is good as well.

I hoped this would be the case. The truck rides way better than I'm used to from most cars, but not as good as the 2004 Suburban I used to haul stuff with. Might need new bushings across the truck overall, but I figured this would be a good first step.

 

[lcdude]

I hoped this would be the case. The truck rides way better than I'm used to from most cars, but not as good as the 2004 Suburban I used to haul stuff with. Might need new bushings across the truck overall, but I figured this would be a good first step.

Indeed. It is worth investing $50 and 60 minutes of your time in this “low hanging fruit”.

 

[Jcalvim1000]

I have an lx 470 and the wishbone link to the height sensor broke on the front passenger side. This causes the front to drop all the way down. Once I replaced the link and matched it to the other side but now the it reset a little higher then normal and it will not adjust heights all and ride is very bouncy. Will a flush fix this or could it be the compressor or globes....any suggestions?

 

[Pyrenees]

Yup get three 1L bottles. I used more than 2, but not all 3. Ride was definitely improved, although the stuff that came out didn’t look bad, so I think one of the POs had done it before.

 

[hurricane11]

HELP! (I cross posted this in a 200 series forum also)

Disclaimer: I am new here! I am a fairly experienced mechanic but new to Lexus. Probably did something stupid, so hopefully you guys can rescue me. My vehicle is a 2011 LX570.

I attempted an AHC flush. I read most of the tutorials and a video on youtube, and I thought I followed the instructions, but I am having an issue. When I start the vehicle to "repressure" the system (step 8 in PADDO LX470 instructions), the vehicle height does not raise back to the normal "L" height.

Here is what I did
1. Put vehicle in "L" height.
2. Vacuumed reservoir tank of dirty AHC fluid with mityvac 7201 fluid extractor. Recovered about 1.5 liters. Initially added 2 liters (and then 1 more to total 3 liters since this is about the volume I recovered from the reservoir and bleeders).
3. Bled all 5 bleeders, starting with accumulator, then Driver Front, Driver Rear, Passenger Front, Passenger Rear.
3. Started vehicle and the pump sounds like it runs for a while, then stops, but the vehicle height does not raise back to L.

I did not start the vehicle after bleeding each bleeder (which I'm wondering was a mistake - causing a low pressure sensor error?). I thought I was following PADDO's instructions and did not need to start it after bleeding each one. I read another tutorial from NTSAINT that said I should not have bled more than 6 ounces without starting. And if I did bleed too much it would require some kind of special reset? (I didn't read it close enough beforehand!).

What am I doing wrong? How do I get the system to pressure back up?

 

[2001LC]

You can't use the 100 series bleed procedure on the 200 series. You've really messed up. New AHC system about $50K

Just kidding!

My understanding system has a fail-safe for low fluid/pressure. Pump has shut down. Go into tech stream and use the test mode, active/test the pump. May need to do a few times.

Do one globe at a time. Start up letting pressurize. Then move to next globe should kept from happening again.

 

[Nolanerd]

has anyone ever considered a partial fluid exchange? that is - lower the vehicle to L mode, and just suck out the full reservoir and refill with fresh fluid? would this help? hurt? be a waste of time if you don't do the whole bleed procedure?

I'm just a little hesitant to flush the system myself. thanks!!

I have a 2013 lx 570

 

[uHu]

There is no point in changing the fluid in the reservoir, as there is no circulation. The fluid is just pumped a few inches up and down the same pipe, giving hardly any exchange of fluid.

 

[bcngator00]

Total Noobie here so please forgive me if my question is covered in this thread and I missed it. I just purchased a '98 LX470. I can get the system to go to high and low, but the ride is horrible. Bounces like mad when you hit the least little bump. I did the fluid level check tonight and only got 4 tick marks from high to low. Would I be wasting my time bleeding the system and getting new fluid in there? The OP stated in his AHC Bleed Process instructions that the bleed and refill should not be attempted if the result s 7 ticks or less. This is the first time I have seen that in my research and it really has me worried. I would appreciate your opinions/insight/experience. Thank you!

 

[trdcorolla]

The graduation numbers you get aren't accurate unless the pressure's are in spec. Check and adjust your pressure to see if you gain any graduations. Some here gain some but I didn't. I had 5 grads and flushed it twice and didn't gain any, so I wasted a bunch of fluid. had to replace my globes and rear springs to get everything in spec.

 

[UGN]

Nothing to worry about. One can is sufficient for a good exchange and bleed, particularly if you're comfortable with working on hydraulic systems and can do it efficiently. For a lot of guys here though this is all new to them and in that case it's better to have more fluid (2 cans) on hand than being left short in the middle of the process; or if it's a first time ever fluid change then you'll benefit from a follow up bleeding to establish a good baseline. The trick is to not drain more than you can replace An opened second can be resealed pretty well and stored for later use.
Edited to include:
Here's my version of a quick and easy 1 can AHC fluid exchange/bleed. Following this process is less likely to get you into trouble by reducing the risk of accidentally bleeding too much fluid thereby allowing air to be drawn into your system.

Materials required. One can of fluid (Toyota suspension fluid, AHC 08886-01805), clear pvc pipe that's a snug fit on the bleeders, 10mm spanner/box wrench/crows foot and a suitable waste fluid container.

This process assumes the fluid level in the reservoir is between max and min at N height before starting. Clean around the reservoir cap and the spout of the AHC fluid can before opening.

1. Lower the vehicle to L and wait 30 seconds for the AHC system to settle and then turn the vehicle off, do not restart until step 8. The fluid level in the reservoir will now be at its highest. Using a turkey baster or similar remove as much fluid as practical from the reservoir. This amount should equal, or be slightly over, 1 liter.
2. Pour the entire 2.5 liters of new fluid into the reservoir, filling it.
3. Now we know that the reservoir's "normal" contents is ~ 1 liter (vehicle in L when fluid level is correct at N) and we have filled it with 2.5 liters so we don't want to drain more than 1.5 liters or else we may come up short.
4. Starting at the height accumulator (12 in long cylinder on DS outer frame rail, between front and rear damper assemblies) drain fluid, closing the bleeder as fluid flow stops which should be ~0.3 liters.
5. Move to the front LH damper and drain until the front is on the bump stops. Both sides will lower and you should drain ~0.4 liters. Again close the bleeder as fluid flow stops.
6. Move to the rear LH damper and drain until the rear is close to/on the bump stops. Both sides will lower and you should drain ~0.3 liters. Again close the bleeder as fluid flow stops.
7. Now we should have drained very close to 1 liter (0.3+0.4+0.3) leaving us about 0.5 liters additional in the reservoir.
8. Start the vehicle and raise to N. The system will refill and recharge with new fluid from the reservoir. The fluid level in the reservoir will lower to slightly over the max line if everything has gone as expected.
9. Turn the vehicle off and do a small, quick bleed on the PS front and rear dampers just to check that there isn't any gas trapped. You don't need to remove very much at all from the PS as essentially all available fluid (there will always be a small residual in each shock actuator that we can't access) gets pushed out when you do the DS and take it to the bump stops as both sides are hydraulically connected.
10. You're done, confirm that the reservoir fluid level is correct - between max and min at N height with the engine running. There is nothing wrong with leaving the level slightly over the max line.

As long as you don't drain more than 1.5 liters you can't mess up and accidentally draw air into the pump/system.

This approach is simpler than others, but slightly more elaborate than the FSM. It is intended to remove as much old fluid as practical in a quick and efficient manner. Hopefully it fills an information gap by associating approximate quantities to the height accumulator and front/rear hydraulic circuits. Hopefully this guidance falls between the very brief FSM directions and other available AHC bleeding procedures that may appear complex and daunting to some.

As either the front or the rear hydraulic circuits are connected would it be fine draining old fluid from the front DS and rear PS dampers? The problem I have the front PS and the rear DS bleeders were missing caps and they could be plugged with dirt and rust. How easy is it to replace those bleeders if I am able to remove them? What are chances to brake them as all 5 points look rusty even if I soak them in PB blaster/liquid wrench for a day? If I drain old fluid from the front left and rear right would it be the same as doing both the front and rear dampers on DS?

 

[uHu]

If you don't drain from one bleeder, you will not bleed air or change the fluid close to the shock and sphere on that corner. The worst fluid is closest to the shocks and spheres, so with only 2 bleeders you would change only half of the fluid which is in greatest need of changing out.
People have managed to change broken bleeders, but there is always a chance of polluting the fluid.

 

[PabloCruise]

Same thoughts, you won’t get the fluid out down by the bleeder, probably where it needs to be changed the most.