Help with AHC Whine (1 Viewer)

[prez1967]

2017 LX570 intermittently whines when the AHC lowers for “easy exit”

Video of noise here: LX570 AHC Whine - https://youtube.com/shorts/dVXe4Zo0Azo?feature=share

Any ideas what it is? Should I be worried? Warranty runs out in a month lll

 

[nwfl4runner]

Not normal - have you checked fluid level?

 

[radman]

interesting. Does it make that sound when lifting?

 

[TeCKis300]

Not sure of the cure, but a good place to start would be to bleed the system to make sure there's no air.

 

[lx200inAR]

From reading the manual. If this is only occurring during lowering, then it almost has to be the return valve. This is the only valve that is in operation during lowering and not any other time (note: there is no electro-mechanical operation of this valve, it functions based on the pressures acting on it). How long does it take for your truck to lower? From the video it looks a little slower than mine, but can't be sure, I've never stop watched it or anything. Wonder if the valve isn't opening fully and is whining as fluid is passing through. It definitely sounds like the whine starts getting quieter as the valve is closing. I'm sure that part isn't "toyota" serviceable generally and you'd have to replace the whole pump assembly. I'm not a hydraulic specialist, so don't know if there is a good method for trying to clean out that part of the system with some sort of flush. If it's air whining as it passes the valve, then I would think it would eventually stop doing it after you lifted and lowered a few times, and also would be an easy fix by doing a full system bleed as mentioned above. Then you just need to figure out how air got into the system.

 

[1world1love]

Definitely not normal and I wouldn't fool around with diagnosing it on your own right now. Take it in so they have a record of the issue before the warranty expires.

 

[prez1967]

The noise only happens upon lowering.

I sent the video to my service writer and his manager. Waiting to hear from them today on scheduling an appointment.

Told them about the issue when it was in earlier this week but "could not replicate". Same goes for the Mark Levinson system not powering the drivers side speakers. Wouldnt do it for them while they had it but when I got home, the speakers were dead again lol

 

[04UZJ100]

I would suggest starting with multiple bleed/refill cycles. Until you are absolutely sure that all the air out of the system. Was the system ever serviced, did they put the correct fluid back in?

Cavitation across control valves (lowering valve) can create all sorts of funky noises as microscopic bubbles of air form and “explode”. Similar concept to shower heads that wine when turned to certain settings.

Other causes for cavitation: incorrect fluid (specific gravity/viscosity) not working with control valve. Worn out/cut valve body and a control valve that is not fully cycling/seating.

 

[Madtiger]

Car still under warranty? If so, go thru Lexus. No need to lift a finger.

 

[prez1967]

Car still under warranty? If so, go thru Lexus. No need to lift a finger.

yup, going back early next week. They can figure it out. always had good luck with dealer in the 6 years we've been dealing with them. I just dont want to run out of warranty in a month and have these intermittent issues become a real problem.

 

[okcfunky]

Sorry to bump from the dead. What was the fix?

I got the same thing going. I do got one pretty leaking hydr ram (front passenger). So if its a whole new pump assy, then for that cost, Id rather go static suspension.

 

[AnyMal]

Ive heard mine hush down when turned off plenty of times while it settles and more when theres a bunch of weight in the back, but never any whine like that. Its smooth.
Also it doesn't always do that in the first place. But AHC will sometimes be not in the right range, like for example in my driveway which is a steep downhill, the butt tends to lift while the front axle compresses on the way into my garage and it'll equalize back to even when i turn it off and get out.

What @lx200inAR and @04UZJ100 said though. Also where do you hear it coming from?

You can also quickly visually check your breather hoses and inlet return hose connections in the right rear wheel well access bay by the resi to see if theres somehow debris or bubbling (but its hard to see).

 

[RavensRemix]

I just made an account and wanted to thank everyone on this post. I had a similar whine, not as serious. Anyway the Lexus dealer I was working with honored my Certified Warranty claim. They determined the AHC pump needed replacing, and stated it was a $4k repair.

I had a 2014 GX460 with the auto leveling suspension in the rear and it never had any issues.

Mine is also a 2017 LX 570, with 56k miles, no off-roading (that I'm aware of). I'm the third owner and it's been certified each time it was re-sold so I thought I was getting something really bulletproof with that kind of logic, haha!

The issue started when the same dealer did the AHC service at 55k miles, so maybe they didn't bleed it properly leading to this pump replacement?

New video by Chris Andrzejczak

photos.app.goo.gl

 

[32cls6speedmt]

I am going to speculate that the contaminated ahc fluid was used during service. Just pure speculation.

 

[bruisecruise]

I'm pretty sure this is just the little breather valve at the end of the hose attached to the point where AHC fluid is added. When you lower the truck fluid fills the reservoir creating air pressure, if the valve is sticking then it will squeal as the air escapes.

You could easily test this by opening up the AHC reservoir access and leaving the tank open to the air, raise/lower the vehicle and see if it makes any more noise.

 

[trudd]

I'm pretty sure this is just the little breather valve at the end of the hose attached to the point where AHC fluid is added. When you lower the truck fluid fills the reservoir creating air pressure, if the valve is sticking then it will squeal as the air escapes.

You could easily test this by opening up the AHC reservoir access and leaving the tank open to the air, raise/lower the vehicle and see if it makes any more noise.

Any tips/suggested methods for cleaning the breather valve? I’ve never touched one before