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

[ntsaint]

I'm planning on changing my AHC fluid this weekend, and have done a lot of research as to the best methods to use.

Everything I found was kind of spread out, so i took some time to combine it all into one step by step document (attached).

Since I've never done this myself, was looking for people on this forum to give me input as to changes in the document, other tips, etc. Then I'll post a final copy.

FYI, the 'I' that's referred to in this document is not me...that's just copy/pasted text from other authors. I take no credit for the content of all this, just the organization and flow.

Thanks in advance.

 

[agaisin]

In terms of tools needed, you can also use a turkey baster or a siphon to empty the reservoir.
In terms of the actual instructions, looks like it's mostly based off the same post I also followed from clublexus (AHC flush - simple and safe - Club Lexus Forums) which was very helpful. However, here's something i would do differently and suggest others do as well - I don't know about 6 oz - maybe that's helpful to some, but to me, my goal is getting rid of the old and replacing with new. SO, I would keep bleeding each accumulator until you see fresh fluid. If you can't tell the difference b/w the old and the new you're one of the lucky ones (you must be changing it way earlier than the 60k recommendation. Personally the difference b/w old and new was obvious and I wasn't satisfied with my flush until I saw fresh fluid come out of each accumulator. The clublexus instructions were a little too conservative for me since you may not end up flushing enough. Just my .02.

 

[RPMLX470]

I read up on the various bleed procedures online and read the one I attached..(FSM procedure - simple, but not very thorough). Below is what I did..

Tools are simple:
-10mm wrench to open and close bleeder screw
-Clear bottle to capture fluid flowing out of the bleeder screws (approx. 32oz gatorade bottle) with a hole drilled into the center of the cap for the clear tubing to slip through (drill the hole just large enough to keep the hose snug)
-Bucket or large bottle to hold old fluid
-New AHC fluid
-A turkey baster or a small hand pump to extract old fluid from the reservoir. I used a vacuum fluid evacuator to suck out the fluid out of the reservoir. If you have the extra funds, this is a great tool for bleeding brakes or extracting fluid out of any reservoir if you have $150 to spare.
http://www.mityvac.com/info_sheets/MV6830.pdf

This is what I did on my bleed...
1. Park on level surface
2. Put vehicle suspension in 'N' mode
3. Turn off vehicle
4. Extract all old fluid from reservoir
5. Filled reservoir to the top with new AHC fluid
6. Remove all 4 rubber caps at each bleeder screw
7. Bleed driver side front actuator by loosening bleeder, when suspension bottoms out, immediately tighten bleeder screw.
8. Start vehicle and wait for the suspension to automatically level itself, then turn off vehicle.
8. Repeat Step 7 and 8 for the passenger side front actuator.
9. Repeat Step 7 and 8 for the driver side rear actuator.
10. Repeat Step 7 and 8 for the passenger side rear actuator.

Additional basic notes:
-Always check the fluid level in the reservoir, don't let it get too low.
-Go through steps 7-10 till the fluid looks clean flowing through the clear tube.
-There is a lot of concern with the vehicle lowering when opening up the bleeder screw...but how low does it go down?
To give you an idea of how much it lowers, the suspension lowers pretty close to when the suspension is in its lowest mode. I took pics and I'll post them up..
-The suspension does get better and better as you drive it around.

 

[ntsaint]

In terms of tools needed, you can also use a turkey baster or a siphon to empty the reservoir.
In terms of the actual instructions, looks like it's mostly based off the same post I also followed from clublexus (AHC flush - simple and safe - Club Lexus Forums) which was very helpful. However, here's something i would do differently and suggest others do as well - I don't know about 6 oz - maybe that's helpful to some, but to me, my goal is getting rid of the old and replacing with new. SO, I would keep bleeding each accumulator until you see fresh fluid. If you can't tell the difference b/w the old and the new you're one of the lucky ones (you must be changing it way earlier than the 60k recommendation. Personally the difference b/w old and new was obvious and I wasn't satisfied with my flush until I saw fresh fluid come out of each accumulator. The clublexus instructions were a little too conservative for me since you may not end up flushing enough. Just my .02.

Good point...added the below, and thanks.

9. Repeat the above steps as necessary. Remember to keep bleeding each accumulator/actuator until you see fresh fluid flowing into the tube. This tells you that all of the older fluid has been flushed from the system.

 

[ntsaint]

I read up on the various bleed procedures online and read the one I attached..(FSM procedure - simple, but not very thorough). Below is what I did..

Tools are simple:
-10mm wrench to open and close bleeder screw
-Clear bottle to capture fluid flowing out of the bleeder screws (approx. 32oz gatorade bottle) with a hole drilled into the center of the cap for the clear tubing to slip through (drill the hole just large enough to keep the hose snug)
-Bucket or large bottle to hold old fluid
-New AHC fluid
-A turkey baster or a small hand pump to extract old fluid from the reservoir. I used a vacuum fluid evacuator to suck out the fluid out of the reservoir. If you have the extra funds, this is a great tool for bleeding brakes or extracting fluid out of any reservoir if you have $150 to spare.
http://www.mityvac.com/info_sheets/MV6830.pdf

This is what I did on my bleed...
1. Park on level surface
2. Put vehicle suspension in 'N' mode
3. Turn off vehicle
4. Extract all old fluid from reservoir
5. Filled reservoir to the top with new AHC fluid
6. Remove all 4 rubber caps at each bleeder screw
7. Bleed driver side front actuator by loosening bleeder, when suspension bottoms out, immediately tighten bleeder screw.
8. Start vehicle and wait for the suspension to automatically level itself, then turn off vehicle.
8. Repeat Step 7 and 8 for the passenger side front actuator.
9. Repeat Step 7 and 8 for the driver side rear actuator.
10. Repeat Step 7 and 8 for the passenger side rear actuator.

Additional basic notes:
-Always check the fluid level in the reservoir, don't let it get too low.
-Go through steps 7-10 till the fluid looks clean flowing through the clear tube.
-There is a lot of concern with the vehicle lowering when opening up the bleeder screw...but how low does it go down?
To give you an idea of how much it lowers, the suspension lowers pretty close to when the suspension is in its lowest mode. I took pics and I'll post them up..
-The suspension does get better and better as you drive it around.

Thanks for the FSM, i made changes to my doc per the above as well. If you do have pics to post, that would be great. I'll add them to the PDF.

 

[ntsaint]

Updated PDF

 

[RPMLX470]

Thanks for the FSM, i made changes to my doc per the above as well. If you do have pics to post, that would be great. I'll add them to the PDF.

here are some pics:

Suspension all full droop in the front, this is how low it goes when you bleed the actuator.

High tech bleed bottle! Check out the dirty fluid that came out.

New AHC fluid

Vacuuming the fluid with a fluid evacuator (operated with shop air)

 

[agaisin]

2. Put vehicle suspension in 'N' mode
3. Turn off vehicle
4. Extract all old fluid from reservoir

This is a mistake - you actually want to empty the reservoir when you are in L. If you do it while in N, you are leaving lots of bad fluid in the system and end up having to do lots more bleeding. Emptying the reservoir is quick and easy compared to bleeding so get into L b/f emptying the reservoir!

 

[RPMLX470]

This is a mistake - you actually want to empty the reservoir when you are in L. If you do it while in N, you are leaving lots of bad fluid in the system and end up having to do lots more bleeding. Emptying the reservoir is quick and easy compared to bleeding so get into L b/f emptying the reservoir!

You're right. I actually did the evacuation in low mode...just forgots to mention.

 

[ntsaint]

OK, finished my fluid change earlier today. There is a NIGHT and DAY difference in the ride. This took only an hour, and was a piece of cake. I used almost all of 2 cans of new AHC fluid. Other supplies cost approx $20.

I'll be doing the final update on the document later tonight. The steps used by RPMLX470 were by far the best.

I took a pic of my before and after AHC fluid. The jug on the left is the NEW fluid. The two jugs on the right are the OLD fluid that was pulled out. Notice any difference?

Again, can't believe how much softer my ride is after this...

 

[ntsaint]

Final AHC Document

I'm sure this can be changed some, but the details are there to make this easy for anyone.

Thanks to RPMLX470 and agaisin.

 

[super50]

I'm sure this can be changed some, but the details are there to make this easy for anyone.

Thanks to RPMLX470 and agaisin.

Great write up. Thank you so much! 75% improvement in the ride.

However I was not able to bleed the rear lines - my wrench would not turn the bleeding bolt, and it stripped the corners.
There seemed to be some rust on there.

Its pretty cramped in there - any advice on how to turn those bolts to bleed the rear AHC fluid lines?

 

[Actualeyes]

Based on Super50's experience it may be wise to hit those bleed points with WD40 first up.

 

[MrGreenJeans]

Its pretty cramped in there - any advice on how to turn those bolts to bleed the rear AHC fluid lines?

PB Blaster / Liquid Wrench, couple applications at least 24 hrs in advance. If the corners of the nut are too rounded for a box wrench, use Vice Grips.



Good luck

ETA - when I did this there was a marked difference between the fist jug of refuse and the second.

Question - RE: those advocating multiple drains on the same globe - isn't this an open system? See clear fluid at one point, shouldn't clear fluid exist at all points?

 

[2003lx470]

I want to thank all who contributed....

My truck is running rough and I need to do this. I was thinking of taking it to the dealer. Now that I have seen what you guys have done, I have the confidant to do it my self.

I will post pictures after the procedure.

 

[2003lx470]

Okay, yesterday I tried to change the AHC fluid. Before changing, tried to test the AHC system by testing the High and Low settings. Took two pictures.

First picture is low setting and second picture at high setting. Difference in fluid between the two levels are 7 points.

Can you tell me, if I am good to change the fluid.

 

[uHu]

Okay, yesterday I tried to change the AHC fluid. Before changing, tried to test the AHC system by testing the High and Low settings. Took two pictures.

First picture is low setting and second picture at high setting. Difference in fluid between the two levels are 7 points.

Can you tell me, if I am good to change the fluid.

1 - Always good to change some fluid, if it hasn't been done lately.

2 - The cap is not sitting right

3 - Fluid level is too high - but probably still OK

4 - 7 graduations:
If the Neutral Pressure and the heights are within specs, 7 grads means that the spheres are shot, and the ride will be rough.
But, if the height at Hi is too low, or the pressure too low, the spheres might still be OK. Not likely that you have any of those two conditions, so probably shot globes.

If you want to find the condition of your spheres and springs, you have to get a code reader of some sort, e.g. TechStream.

 

[Lx470iH8Mud]

If it were me I would complete a flush and go from there, my vehicle only had 40,000miles when I flushed it and the fluid was ugly, made all the difference and the system functioned how it should after the flush. It's cheap and easy enough to do yourself and go from there. The fluid that came out of mine was dark grey/metallic looking. It never had the fluid changed or tampered with prior and now is as smooth as silk. If your system was operating at less than 7 graduations I would be careful but you may notice a 2-3 graduation increase with fresh fluid...just my two cents.

 

[2003lx470]

Can someone please post pictures how the high and low fluid settings should be? Thanks

 

[FlammableFishie]

Can someone please post pictures how the high and low fluid settings should be? Thanks

I don't have an LX but my guess would be when you're in "Low" the fluid should be that the "Max" line, and when you're in "High" the fluid should be at the "Min" line. Obviously neutral will be somewhere in between. I could be wrong, but this seems logical to me.