2006 LX470... After finding my front suspension practically as low as it could get, the AHC system on the dash was flashing OFF. I looked below to find what looked/smelled like suspension fluid... slow drips from somewhere in the wheel well. Can't pinpoint the leak as the top of tire is 1" from the wheel well ceiling.
Checked the fluid reservoir under the hood, completely dry. I got a 2.5L can of suspension fluid but am hesitant to fill as it would just leak right out.
Does anyone know the best way to track down the leak? Or at least what I should check first?
As shown in your picture at Post #6 taken from the FSM, there are several different parts including retainers and cushions at the top of the ‘shock absorber’ -- which is just a hydraulic strut on AHC-equipped vehicles -- it is not a damper in the manner of conventional suspensions. Damping takes place at the Damping Force Control Actuators to which the ‘globes’ are attached.
Suggest input your VIN at
https://partsouq.com/ and explore towards the end of the “Power Train/Chassis” section looking for the AHC suspension information -- this provides a way of identifying the relevant Part Numbers. This was the source of the first two pictures below.
Your picture at Post #4 points to the top cushion. This is not an O-ring -- the relevant O-ring is not visible because it is inside the hydraulic connection -- as depicted in this link:
I'm replacing my front and rear AHC shocks with new ones and I note that the FSM advises replacing the O-rings and back up rings when doing so: If a description of how to do this exists on the forum (or elsewhere) I haven't been able to find it. Does anyone have instructions and/or...
forum.ih8mud.com
The cap bolts must be removed as depicted by
@OEMGUY0720 in Post #7 to get to the internal O-ring 90301-11022 AND the back-up ring 90562-12003 as noted by
@2001LC. These two rings are both vitally important, must be in the correct postion and are responsible for the pressure seals at this connection, not the cushion visible from the outside.
If taking on this job of dealing with the O-rings and back-up rings, it would worthwhile also to consider removing each Front wheel to enable removal of both Front ‘shock absorbers’ and then replacing the top cushion and the bottom bush in each case. Unless the ‘shock absorber’ itself is rusted out or wildly leaking, replacement of the actual 'shock absorber' should not be necessary. If you do change out the 'shock absorbers' then OEM Toyota/Lexus parts will arrive with the Lower Bush already installed, but if I remember correctly, the Upper Cushion must be purchased separately. There are some differences between Upper Cushion Part Numbers with different Model Years, so it is important to research the details.
Your mention of
“… threads also mentioned that adjusting the pressure with Techstream can slow/stop the leak”. This may not correct the leak discussed in this thread because the quotation refers to leaks at the seals
inside the actual ‘shock absorber’ -- see pic below -- caused by excessive AHC pressures. Often this latter kind of leak can be fixed by correcting AHC pressures.
Just to be clear, AHC pressure correction requires shifting more load onto the Front torsion bars (by adjusting or indexing torsion bars) and Rear coil springs (by adding spacers or replacing springs) and decreasing the load on the AHC system. Correcting AHC pressures has nothing to do with the condition of the ‘globes’.
However, good ‘globes’ ARE one of the essential requirements for good ride comfort, so testing for good ‘globe’ condition is a good idea for that purpose.
The following link has some good pictures and a descriptive video which may help:
Front AHC shock bushing and cushion replacement - https://forum.ih8mud.com/threads/front-ahc-shock-bushing-and-cushion-replacement.1221355/
…. and some more detail at:
Successful AHC refresh - my experience and quick writeup - https://forum.ih8mud.com/threads/successful-ahc-refresh-my-experience-and-quick-writeup.1279980/
Hang in there! The AHC/TEMS systems are best “learned by working on them” -- and they are among the simplest systems on LC100/LX470 vehicles -- way less complicated than brakes, steering, transmission, drivelines and axles, engine control, etc, etc, etc.
O-ring:
Back-up Ring:
