DISCLAIMER: The following suggestions are intended as a general description of the type of work involved in the removal and replacement of the hydraulic accumulators in the level control suspension system of the Lexus LX-470. B and B Suspension and Author deny any suitability of fitness of purpose, accuracy, safety or any other attribute-either explicit or implied. Complete and full responsibility for any use made of these suggestions rests with the user thereof, not the author or B and B Suspension.
1. Safety is foremost and essential. Do not ever work under the vehicle unless it is well supported by suitable jack-stands, blocks, or other such equipment on which one trusts his LIFE. The LX-470 is a heavy vehicle and sits several inches higher off the ground than an automobile. This means most automotive jack-stands are not high enough to support the LX-470 with wheels almost off the ground. Up to 4 inches of wood blocks (8 inch long 2x4) will need to be placed between the jack stand and the LX-470 frame rail. If accumulators on only one end are to be replaced, it is also necessary to block up the other end.
2. With the vehicle securely supported apply vigorous push-pull shove in a horizontal direction side-to-side to test and verify stability BEFORE getting under it.
3. The 4 suspension accumulators are the flattened softball sized & shaped black metal objects located under the running boards, outboard of the frame rails, between the front and rear wheels. They are screwed into the hydraulic control valves, which allow high pressure oil to flow into the strut, or flow out to the reservoir, as commanded by the computer control. On each control valve is a hexagonal brake-bleeder which is opened to allow suspension oil (or air) to flow out. The bleeders (on each side or all 4) depending on how many are to be removed) should be opened and any pressure released before trying to remove the accumulators. Re-close the bleeder when the pressure is all gone. A flexible hose can be slipped over the nipple end on the bleeder to direct the escaping oil to a suitable container. DO NOT attempt to reuse the oil. The 3 biggest enemies of hydraulic systems are dirt, dirt, and dirt. Oil is cheap relative to the system components that dirt will ruin. You need to have a can (2 liters) of Toyota/Lexus suspension oil on-hand to replace that which will be drained.
4. The seal between the accumulator and the hydraulic control valve is accomplished by a captive O-ring, and is not dependent on the tightness with which the accumulator is installed. It need be only hand tight enough to preclude loosening during vehicle operation. However, factory installation may be tighter or the accumulator may be stuck such that a wrench is necessary to loosen it. Sometimes simply firmly tapping on the accumulator will un-stick it so it can be turned by hand. Normally however, a wrench is needed. You can use either a 36MM (1-1/2inch) open-end wrench that has been ground to ¼ inch thickness to fit into the space. Another type of wrench is called a chain-wrench, which is suitable for odd shaped and round objects of various sizes. These are available at tool shops, Northerntool.com, and many better auto-parts and hardware stores.
5. Reinstallation is simple—just turn the recharged accumulator back into the valve body and snug it up by hand.
6. Before removing the supporting devices, refill the height control reservoir (clear plastic tank on passenger side of engine compartment back close to the windshield), the start the engine and let it run a few seconds. Shut the engine off, and then loosen each bleeder in turn and allow any trapped air to flow out. Retighten the bleeder when each valve has been bled. Restart the engine as needed to restore the system pressure during the bleeding process. The AHC computer shuts off the hydraulic pump if it does not sense pressure within 1/4 second. Thus, it will be necessary to srart and stop the engine up to a dozen (or more) times until pressure builds up and the 'off' warning light remains unilluminated.
WARNING!! DO NOT get under the vehicle with the engine running.
7. Remove the supports carefully and drive the vehicle a few minutes, moving the height control to each position several times to ensure all the air has been purged. Then re-check and top-up the suspension oil reservoir as needed.
8. B and B Suspension has learned some LX-470 owners driving with flat accumulators have experienced air getting into the system hydraulic pump,resulting in a system shutdown and warning light. Please refer to the general explanation page for further information. IMPORTANT NOTE: Dealer & factory diagnostic procedure apparently fails to properly troubleshoot this 'air locked'condition, resulting in a 'faulty pump' verdict. The pump discharge line must be disconnected and the pump then operated to purge the air before it is reconnected. Air cannot be purged from the pump with the discharge line connected.