newbie in need of help - AHC AVS question (2 Viewers)

[00lx470]

Ok, here goes. I just purchased a 2000 LX470 with 150K miles earlier this year. I asked the seller's mechanic about any suspension issues and he and my mechanic said it looks good. In retrospect, I didnt have enough information to check as well as I should have, or be as specific as i should have.

After spending a week or so reading this forum and others about AHC, here's my deal. My AHC reservoir is filled way past MAX, when at the N height. After doing the check folks recommended, I only got about 7 ticks of movement in the fluid level after moving the AHC from L to H.

I then went through the maintenance records looking specifically at the 60K and 120K service sheets. The 60K was done at a Lexus dealership, but no mention of AHC fluid replacement. Same for the 120K.

Long intro, heres the questions: can i just turn off the AHC and not worry about it, i have no real need to use it? How urgent is this if the spheres / globes are shot as my test may indicate? Are the accumulators used in the avs system, or stand alone? Lastly, anyone know of a shop in the midatlantic area that does good work putting OEM LC suspensions in LXs?

Thanks for any help guys.

 

[TXLX100]

Does it ride rough or are you more concerned with the amount of movement the system generates? Sounds like the fluid needs to be changed based upon your description. You could pull all the fuses for the system, but I think the result is worse than driving with a problem system turned on. I've seen several threads in here about deleting the AHC system and going to conventional suspension / lift.

 

[00lx470]

it rides just fine as far i can tell. teh comfort setting is on 3, i havent changed that. very soft over speed bumps, not super soft over cracks in pavement, but way smoother than my 2004 4runner.

Im not dead set on fiddling with it. Mostly, for now at least, I just want a trouble daily driver for the wife and kids. In my mind anyway, i figured we would get another 100k miles (bring it to 250K total) adn then I would put in an LC OEM suspension and some fun stuff.

not really sure what, if anything, i should be concerned about. thoughts? can i just have the fluid replaced and leave it be?

 

[00lx470]

i meant trouble free daily driver, of course.

 

[parnoren]

Somebody with better knowledge than I might step in here, but I believe your spheres are ok as you mention it moves smoothly over bumps. I usually test my "ride softness" by going over the same road bump twice and change the comfort setting from "soft" to "hard". I can definitely tell the difference.

I have 150,000 miles on original spheres. I have changed the fluid twice.

Maybe change the fluid and check the graduations again. Old fluid cannot be good for the system.

 

[TXLX100]

I second this ^. If the accumulators go bad or if water got in the system, the ride quality is very stiff, especially over bumps. I think the service interval is every 30k on the fluid. If its been much longer than that or more than a few years, it's probably time to change the fluid. If and when the AHC requires any major repair on my LX, I'll probably remove the system and get a small lift, the parts start adding up quickly.

 

[00lx470]

thanks for the help everyone, glad to hear its not necessarily a huge fix. nobody mentioned this, but any ideas / info about the AHC reservoir being overly filled? Im about as mechanical as a bowling ball, whats an AHC replacement run at the average dealership, or should i trust my local mechanic with that?

 

[TXLX100]

It depends on which parts you need to replace. The accumulators are usually the parts that fail; they cost about $600 each for the part alone and there are 4 of them on your vehicle. There are also 4 hydraulic rams/shocks, plus the pump. It's probably not less than $5k-6k at the dealer. Here is an article that kinds of explains the system:

http://activesuspensionsystems.com/lelx470susy.html

 

[PADDO]

Here are my thoughts. Before you throw your baby out with the bath water replace the fluid. Its any easy job, no special tools needed, fluid costs around $45 per 2.5 litre can. There are plenty of good threads on AHC fluid replacement here. Most change their fluid every 50-60k or so. I'm at 120k miles with no AHC issues, have done 2 fluid changeouts with one torsion bar adjustment session and added 10mm rear coil spacers. Happy so far. After new fluid comes your neutral pressures. Almost guarantee if they weren't checked/adjusted by PO then they will be out of spec (too high). You can pay a shop with techstream to read off your pressures and other adjustable parameters, buy the $35 mini VCI setup and do the readings yourself, or least best - blind crank both TB adjustment nuts 3 full turns cw and see how that pans out. Safe bet the rear coils have diminished spring rate with age too, either stick 10mm coil spacers in for $25 parts, new coils for about $200 parts only, or ignore high rear pressure if its not outrageously out of spec.

You report AHC reservoir level is way too high, that is kind of troublesome to me because our AHC systems us specific Toyota fluid, no generic equivalents are available off someone else's shelf, not like topping off the power steering or brake fluid reservoirs with a generic (MY specific) Tranny fluid or DOT whatever compliant brake fluid. Any clown can top off the PS reservoir at jiffy-oline-speedy-oil-change palace, but I'd like to think that anyone adjusting the AHC fluid level knows what they are doing and is using the only approved fluid, and if they know what they are doing then why would the fluid level be left way to high? Kind of implies, potentially, that is could have been topped off with something other than AHC fluid. Just a thought, don't want to induce unfounded issues or concerns. Here's what I'd do first off - baseline your system with known good AHC fluid and check/adjust neutral pressures back to spec. And, in the absence of flashing lights, stuck at low or stink bug vehicle attitude - and whilst maintaining a ride that you're comfortable with - enjoy your vehicle. If you're not comfortable with changing the fluid yourself call your local Toy/Lex service department, tell them you'd like a price on an AHC fluid change with a quick read of your neutral pressures, ask if they'll crank TB's to get the pressures in spec if required. Price? its a 20min job so billable for 1 hour plus 1 maybe 2 cans of fluid and shop fees - dunno - maybe around $200-$250. Any independent shop could do these basics, as long as they use Toy AHC fluid and have access to Techstream. Good luck, and don't forget people tend to report system failures, not so much the good news.

 

[00lx470]

PADDO, youre awesome. thanks very much, great info. i actually thought the same thing, hoping they didnt add in anything too harmful in there with the normal AHC fluid. I called my local toy dealer, they said we have no idea how, call lexus. Called lexus, after a 10 minute wait they found a guy that quoted me $370 for just the fluid replacement and readout, doesn't include any adjustments to the neutral pressures if need be. I think im gonna go crazy and try this myself.

Before I do however, how urgent is this fluid flush in your opinion, like gotta be this weekend, or in the next few months ok? Very modest driving needs for now, about 50 to 60 miles per week, but most is city driving.

Rest assured Im enjoying the vehicle, but thanks for the good advice. Never driven such a nice solid well put together vehicle. Im a big fan of buying once and buying right, overall we are very happy with it, any AHC issues notwithstanding. The goal from the get go was to get at least another 10 years / 100K miles out of it, hence my questions on urgency, etc. Eventually, when spheres fail, or other some expensive AHC fix is needed, Ill just put in an OEM LC suspension.

 

[TXLX100]

I would replace the fluid sooner than later, it's a basic maintenance item on a very expensive system. I think the going rate around here for AHC fluid replacement is around $160.

 

[00lx470]

makes sense, i intend to. just want to take my time checking out those how to threads so i dont make it worse!

 

[00lx470]

saved NTSAINT's pdf to my computer, Im sure Ill have questions, but it doesnt look too bad. hard to believe my local lexus guys wants almost $400 for that service.

 

[PADDO]

X2 on replacing the fluid sooner rather than later. Definitely a DIY task, particularly if the local guy wants $370!

 

[00lx470]

PADDO, have you run that test on your LX. Im realizing now i never turned the engine off, i wonder if that would have an effect on the result. immaterial i suppose, either way, i will replace the fluid (ordered it about an hour ago) and go from there. could uneven neutral pressures have an effect on that result i had also? thinking the shocks feel fine, so maybe a fluid flush and torsion tweak, as you suggested, might have me right as rain.

 

[parnoren]

Just make sure you keep an eye on the level in the reservoir at all times as you DO NOT want it to go dry and introduce air into the system. Keep filling it up between bleedings and you should not have a problem. You can always suck out the excess after you're done if the level is too high.

 

[PADDO]

PADDO, have you run that test on your LX. Im realizing now i never turned the engine off, i wonder if that would have an effect on the result. immaterial i suppose, either way, i will replace the fluid (ordered it about an hour ago) and go from there. could uneven neutral pressures have an effect on that result i had also? thinking the shocks feel fine, so maybe a fluid flush and torsion tweak, as you suggested, might have me right as rain.

The reservoir low to high fluid level check? yep done that a few times, get around 11 grads, I mark off the levels with a sharpie dot, takes the guess work out of interpreting what's happening and its a good witness mark reference for next time you check. People report up to 14 grads for a new/rebuilt system. Engine running or off doesn't make a difference as long as the pump has finished its charge cycle. When the neutral pressures are read electronically (as opposed to physically hooking up a pressure gauge to each globe assy) you are reading the pump output pressures in the front, rear and main accumulator hydraulic circuits and not individual actual pressures specific to each globe for each corner. It is what it is, in that I'm not aware of any way of definitively isolating a failed globe insitu, other than putting the system in manual test mode and jumping on each corner to check if each corner has the same level of damping. You're doing the right thing by replacing the fluid and setting the level correctly. One can of fluid is about the minimum to do all five points so don't expect too much excess that will need to be drained off. If you lower the vehicle (to fill the reservoir) then pull as much old fluid off as you can with a turkey baster or whatever you'll find that you can fit pretty much the whole 2.5 litre new can in. Do this with the vehicle off so there is no chance of pulling air into the system. Then, as you bleed each point you'll lower the reservoir's level a bit and if you find that you reach the medium/low level mark and still have bleed points to go then stop, you'll need another can of fluid. I rotate around each bleed point twice, first pass bleed the minimum amount to get fresh fluid, move to the next point, checking as you go how much the reservoir has dropped to gauge how you're progressing. Ideally you get to the end stage where all five points are showing nice fresh fluid, no bubbles and the reservoir level is halfway between min/max. Assuming all goes well you could then think about swinging off the TB adjuster bolts 2 or 3 turns if you like and see how that rides. Good luck.

 

[00lx470]

thanks for the info, supports nicely the instructions i found on this forum. i ordered two cans of fluid last night, ill let you know how it goes!

thanks again everybody, you are all very helpful and responsive and patient with a guy that doesnt know to much.