LX570 AHC “Basics” - Added as sticky thread for AHC Issues (5 Viewers)

[longranger]

Sorry. No that’s Fahrenheit. So would be like -40 to -50 Celsius.

Thank you for clarification.

 

[longranger]

Thanks for the post, Longranger. I like the idea. I've had AHC-equipped LXs for almost 14 years now and have not had one AHC-related problem and I do not cruise malls - I use the heck out of my trucks.

That said, I do ensure I follow the maintenance schedule for AHC service. I do the flushes myself and they are not any more difficult than a brake system bleed, which I also do according to The Book. That's probably the only post-purchase preventive maintenance that is necessary.

Ok, so here’s an update on the $330 dealer “flush” (the recommended 60K flush) I had the dealer perform bc service records didn’t have it, and it was an important item I wanted to benchmark and restore to as close to factory as possible. Dealer mechanics apparently did a “1 can flush” as opposed to a “full flush” (bleeding all four accumulator/damper aggregates at all four corners).

How I found out: ride was softer/smoother after the “flush” last week — then, yesterday, I noticed a rough ride (L,N,H work, but I can feel EVERY imperfection in road surface) — which wasn’t the case before. I tried changing damping settings (from normal to sport to normal to comfort) with no apparent change. Felt like dampers were not working at all.

Climbed under the truck, and voila, one of the four globes is leaking YELLOW fluid from its “nut nipple” (don’t know what it’s called — the outermost part of the globe — see photos). I popped the AHC reservoir hatch behind the rear passenger wheel well, and fluid is within range but still dark. Moreover, after thoroughly examining all four bleeder plugs at four corners, I found that only the two rear ones had been opened (fresh wrench scars on bleeder nuts and new rubber bleeder plugs). The front were untouched — which is infuriating.

Next, the reservoir cap was not touched, which suggests the new fluid was put in through a hose connector (!?!?). Confusing as hell.

Call to the service department revealed that the “master mechanic” who was supposed to be doing the flush was not the one who actually did it, but some “understudy” — which is FUBAR beyond FUBAR bc the guy told me he’d be doing the work personally and was the one who emphasized the importance of doing everything “by the book”.

I’m heading back to service department to demand: (1) new flush, (2) to do system pressure checks (before and after), (3) to potentially replace the leaking globe (can someone explain why it’d be leaking YELLOW fluid? And from that particular location?), and to (4) get my $$ back for the “full flush” the bastards didn’t perform.

Here’s my theory on what happened. They bled rear accumulators/dampers, and filled lost fluid. Then when system was readjusting over next days, the pressures were out of whack, leading to a rupture on one of the diaphragms in the globes. Does this seem plausible? Any similar experiences/thoughts/suggestions?

 

[gaijin]

 

[Mixelplix]

I would lose my mind!

The most concerning part of this is what the heck is the yellow fluid? My understanding of the AHC globe is that it's a bladder pressurized with some gas, and the pink AHC fluid surrounds it. If that's correct, the only way you'd get yellow fluid is by the tech putting it in there.

 

[longranger]

I would lose my mind!

The most concerning part of this is what the heck is the yellow fluid? My understanding of the AHC globe is that it's a bladder pressurized with some gas, and the pink AHC fluid surrounds it. If that's correct, the only way you'd get yellow fluid is by the tech putting it in there.

Yup, the old fluid (which I asked for sample of — and photo of which is up above on thread) was coffee colored (brown and clear). I tried to sniff the yellow, but couldn’t really ID it or get a good scent profile. BTW - echoing some earlier concerns, the AHC fluid is very toxic, so please be careful when “sniffing” — high school chemistry rules apply.

 

[longranger]

My AHC reservoir cap was not removed by dealer mechanics, which suggests fluid was sucked out/poured in through the tube sticking out of the AHC reservoir container (which does appear to have been moved). What’s the tool that would/could accomplish that?

 

[SWUtah]

That “Sucks” keep us posted. What’s the dealers name

 

[longranger]

Globe that is now leaking is driver-side rear — FWIW. Three others are dry. Prior to “flush” by dealer, no leaks and no performance issues.

 

[longranger]

Yeah, it’s Lexus of Memphis. I’m not faulting them for leaky globe just yet, but definitely for failure to perform a full flush as was expressly requested and discussed.

Several other diagnostic pointers (maybe unique to my truck but I suspect are more generalizable): (1) dash and center console and interior trim started creaking like crazy over roads that previously felt glass smooth; (2) gas pedal transfers road vibrations where previously — just smooth; (3) highway speed auto-leveling stopped working it seems (so I’m riding in N, much higher than previously at highway speeds).

 

[longranger]

I would lose my mind!

The most concerning part of this is what the heck is the yellow fluid? My understanding of the AHC globe is that it's a bladder pressurized with some gas, and the pink AHC fluid surrounds it. If that's correct, the only way you'd get yellow fluid is by the tech putting it in there.

Yeah, my recollection is that it’s pressurized nitrogen that’s behind the bladder (chamber that’s away from where globe is mounted).

 

[SWUtah]

I would go back go in and see the general manager and repeat this entire story along with the names of the people you talk to and tell him you want it fixed

 

[longranger]

I would go back go in and see the general manager and repeat this entire story along with the names of the people you talk to and tell him you want it fixed

Yeah, just arrived at dealer and started the process now.

 

[longranger]

The conversation with the lead mechanic who worked on the suspension went OK. He said this is the first 200-series that he’s seen with a leaking globe, and that they’d need to take it in to examine further. I left the four take-off globe/actuators that I had bought off EBay two months ago for this occasion, though I didn’t think I’d need them this early.

When I pointed out that my examination revealed that the front bleeder plugs were not touched, and said that it looks like it was not a full flush that we discussed, but rather the “1-liter flush” — he shot back saying, “that’s not how the flush is done.” Which leads to the following question: are there any Lexus/Toyota-trained folks here who can shed light on the current best-practice for doing a 200-series AHC fluid flush?

Even with all the knowledge I’m gathering here and elsewhere, I deferred to the mechanic whose job it is to work on these trucks and cars on a daily basis. The truck is at the dealer, and will post updates as they come in.

The fact that I have a set of new-ish (2017) front and back take off globes/accumulators/actuators leads to the following questions, that were the subject of numerous discussions on 100-series AHC threads: “if one globe is changed, should I also automatically replace its corresponding sibling?”. So if I change, driver rear, should I also change passenger rear (given how they are more immediately connected in terms of fluid dynamics)? Should I do all four? Has anyone changed out all four globes/actuators/etc. on a 200-series?

 

[grinchy]

is this the same master mechanic that pronounced your ahc solid at purchase time?

 

[TonyP]

Bleeding for your wacky, silly, AHC.

 

[longranger]

is this the same master mechanic that pronounced your ahc solid at purchase time?

No, different tech — and AHC was solid, corrosion commensurate with age, family truck with no wheeling history/damage/scars, and worked well until the moment I got the flush. Key point that guy stressed was to not fix anything that wasn’t broken — and that applied to the AHC specifically. I was the one who requested the fluid flush to go by the maintenance schedule bc it was not done at 60K.

What emerges is a “damned if you do, damned if you don’t” Catch-22. Do a flush per schedule and run the risk of messing up a factory system that’s running well. Don’t do a flush and run the risk of deferring maintenance and causing damage.

 

[longranger]

Bleeding for your wacky, silly, AHC.

Thanks for uploading again. I’m familiar with this and read several times, and the language concerning “first time” and “second time” is confusing. All told, all four corners are supposed to be bled during a single “full flush” — as well as a fifth bleeder plug somewhere — is that correct?

 

[TonyP]

No idea.
I have real suspension.

 

[longranger]

No idea.
I have real suspension.

Real gold star suspension.

 

[SWUtah]

You talked to the grease monkey that F'ed up your AHC. Good example for future problems. I took my LX by a sister LX dealership to the one I bought it from, just to get a free car wash. Suppose to take about 15 minutes so I went in the dealership and ate a free lunch. 45 minutes went by and I found my LX parked not even in line for the car wash. I got in my LX drove around to the front and went in and demanded to talk with the GM. He saw me pacing and looking at him while he was in his meeting. Anyway he ended chewing out the service manager and having my LX detailed hand wash waxed carpets shampooed and he gave me 2 tickets to the pro golf tournament they were co sponsor along with entrance to the hospitality tent. I think you will find that your actions will only get you a large bill $$$. If the GM asks like they always do why you did not take the problem to the service manager, look him in the eye and tell him that if you were GM you would want to know when they were not treating the customer right or in your case damaging their vehicle.