Rear shock leaking, AHC issue? (1 Viewer)

[dealmaker]

So last go-round at my mechanics, and he pointed out that the right rear shock was leaking. Not dripping on to the ground, but sorta gathering at the bottom of the shock mount. I crawled under and it seems to be coming from up inside the lower half of the shock. Did not see any evidence of it coming from anywhere else. Both rear shocks seems to be covered with a greasy grime on their bottom halves only. Is it normal for these things to leak at the seals or something? The parts cost quote to replace is $430 each.

Is there anything I should look for or try before dropping a G into replacing the rear shocks? The AHC fluid is not clear, so I'll have the AHC fluid changed. Should I be replacing the rear coils too? I read in a few other AHC drama threads that its recommended to replace 'em every 5 yrs as they're softer than the non-AHC coils.

2006 LX470 w/65k miles. It's a kid/grocery/dog schlepper, and the heaviest load it carries is 5-6 kids to/from school.

Any advice offered is greatly appreciated.

 

[jmd93]

Are you sure its leaking? Our lx has nearly 160k miles and the AHC is all original minus the sensors and is still all working very well (knock on wood)

 

[dealmaker]

I'm not certain its leaking, only going by what the mechanic reported to me and by how the shocks look.
Top photo is rear PS, bottom photo is rear DS. On the top photo, the little smudge an inch above and to the right of the lower mount is from my finger. The reportedly leaky shock was the PS side. A couple days ago it looked a bit wetter near the bottom. As you can see from the pics, both sides lower tubes are grimey, while the upper tubes are not. Would seem to indicate some seals inside might have issues?

Any and all advice is greatly appreciated. If I replace these rear shocks, I'l prolly replace the rear coils too based on the threads I've read in there of them going soft in 5-6 yrs, and that'll set me back about 1.5K total. That's on top of the cracked windshield and alternator that I've already replaced this year.

 

[hoser]

I think you are getting taken on the rear AHC shocks. They don't even do any damping. They show up around $170/ea online. And I believe they are the same for both Lexus and Toyota. Give any of the trusty mud vendors a call.

48530‑69145

 

[dealmaker]

Yeah, I have emails going back & forth w/Sam at Lowes and see that they available for far below $430. I will confirm w/my mechanic if his price was part only, or includes the labor. Based on another thread here, taking those mofo's off is a PITA, starting with finding the right tool for the job.

I think you are getting taken on the rear AHC shocks. They don't even do any damping. They show up around $170/ea online. And I believe they are the same for both Lexus and Toyota. Give any of the trusty mud vendors a call.

48530‑69145

 

[cruiser03]

Your shocks are definitely leaking. I have the same problem. I replaced my front shocks last year. The rears as i understand it are difficult to remove since it is very tight working there and the nut needs a 2 foot cheater to break it loose. Each shock is $178. I buy my parts at parkplacelexusparts. You will need the little o ring also that seals the hose to the shock. I am thinking about having the dealer do this one. You can drive quite a while leaking just check your AHC fluid level frequently. When you are replacing the shock, put in new springs. Your ride will be smoother and you will not put so much load on the shocks - they will last longer.

 

[Texasoil]

The AHC 'shocks' are simply hydraulic jacks---nothing inside to wear. Leaking has two related causes.

1) failure to regularly change the oil in the system--ALL of it, not just the reservoir. Oil does not circulate in the system unless you change the height setting. The shaft seals will get hard and leak is the AHC oil is not renewed every 30K miles.

2) When the accumulators (actuators in translated Japanese) get low/flat (harsh ride), internal pressure in the strut skyrockets when bumps are hit, forcing oil back to the reservoir through the pressure relief valve. That very high transient pressure will force oil past the shaft seal--but this stops when the accumulators are replaced.

 

[imzjustplayin]

I'm confused, aren't the shocks a separate, independent device on the LX470 vehicles? That just because the shocks are bad, that it doesn't mean the AHC system is malfunctioning?


If the shocks are leaking like listed in the above OP, can you buy aftermarket shocks and call it a day? I don't want to mess the AHC system especially if it isn't causing any issues.

 

[TXLX100]

The AHC trucks do not have standard shock absorbers like you would see on most cars and trucks. The system uses the AHC shocks (hydraulic rams), accumulators, and pump to perform i) height control and ii) shock absorption. AHC trucks still use torsion bars and springs to support the vehicle.

Air ride vehicles use a combination of standard shocks and air bags (to support the vehicle weight).

 

[Actualeyes]

One thing to add... Replacing rear coils is straightforward as is turning up the torsion bars. Top nuts on AHC shocks are the buggers.

 

[Bfaiers]

Is there instruction on how to remove the rear ahc shock absorbers.

 

[rustydrummer]

Is there instruction on how to remove the rear ahc shock absorbers.

I recently did mine, it's no different than the standard rear shocks, which are PITA themselves, except that you must first bleed the pressure off of the system and then remove the hydraulic line attachment from the top of the shock. Once the hydraulic line itself is disconnected, the remaining connection makes it to where the top shock nut is recessed and very difficult to get a wrench on. I ended up using a low profile O2 sensor socket to get to it, which happened to be the right size thankfully, 22mm i believe. It was slow going, but got the job done. All in all, I didn't think it was as bad as some have made it sound like. Remove the spare to give yourself room to work and just roll back your sleeves and get at it. As I said, I replaced my entire AHC with standard OME setup a few months ago, so let me know if you have any questions as its still pretty fresh in my mind. Good luck.


...via IH8MUD app

 

[2003lx470]

The AHC 'shocks' are simply hydraulic jacks---nothing inside to wear. Leaking has two related causes.

1) failure to regularly change the oil in the system--ALL of it, not just the reservoir. Oil does not circulate in the system unless you change the height setting. The shaft seals will get hard and leak is the AHC oil is not renewed every 30K miles.

2) When the accumulators (actuators in translated Japanese) get low/flat (harsh ride), internal pressure in the strut skyrockets when bumps are hit, forcing oil back to the reservoir through the pressure relief valve. That very high transient pressure will force oil past the shaft seal--but this stops when the accumulators are replaced.

#2 is "SPOT ON":
I bought my LX 470 in 2009 (38k miles) and the ride was never smooth. It has now 68,000 miles. Becasue the ride was rough/harsh, few months back, replaced the AHC fluid and ride never improved. I thought of changing 4 shocks. I had to take the lexus to the dealer for an window issue and informed them the harsh/rough ride. They check the "AHC System" and told me both back ACCUMULATORS need replacement. Because this was covered under the warranty, I told them to change. When I got the truck back, ride difference was day and night.

So (my 0.02c) is, if you are having a rough/harsh ride, may be your accumulators need replacement.

 

[Bfaiers]

I recently did mine, it's no different than the standard rear shocks, which are PITA themselves, except that you must first bleed the pressure off of the system and then remove the hydraulic line attachment from the top of the shock. Once the hydraulic line itself is disconnected, the remaining connection makes it to where the top shock nut is recessed and very difficult to get a wrench on. I ended up using a low profile O2 sensor socket to get to it, which happened to be the right size thankfully, 22mm i believe. It was slow going, but got the job done. All in all, I didn't think it was as bad as some have made it sound like. Remove the spare to give yourself room to work and just roll back your sleeves and get at it. As I said, I replaced my entire AHC with standard OME setup a few months ago, so let me know if you have any questions as its still pretty fresh in my mind. Good luck.


...via IH8MUD app

Thanks for the info especially on the socket to use. About 8,000 miles ago I completly flushed the AHC with new fluid. The only reason I want to replace the shocks is that the outer casing is rusting and you can see the ram. the AHC is working prefectly with no leaks but I am a bit concerned that with the ram being exposed it will allow dirt to contaminate the outer seals. What I would like to know, what is the correct procedure for bleeding the system once I have fitted the new shock absorbers? Would there be an advantage of filling the shocks with oil thus reducing the amount of air getting into the system. I have read some stories where the shocks have been replaced and then had a great deal of trouble getting the system bled of air. Why did you go to to OME setup after replacing your shocks? What have you done with the shocks that you removed?

 

[2003lx470]

Is there instruction on how to remove the rear ahc shock absorbers.

 

[Bfaiers]

Brilliant, thanks for the pics, will certainly help.

 

[rustydrummer]

Thanks for the info especially on the socket to use. About 8,000 miles ago I completly flushed the AHC with new fluid. The only reason I want to replace the shocks is that the outer casing is rusting and you can see the ram. the AHC is working prefectly with no leaks but I am a bit concerned that with the ram being exposed it will allow dirt to contaminate the outer seals. What I would like to know, what is the correct procedure for bleeding the system once I have fitted the new shock absorbers? Would there be an advantage of filling the shocks with oil thus reducing the amount of air getting into the system. I have read some stories where the shocks have been replaced and then had a great deal of trouble getting the system bled of air. Why did you go to to OME setup after replacing your shocks? What have you done with the shocks that you removed?

My actuators went bad so I just replaced the system with standard coils so I didn't have to worry about the AHC probs anymore. I still have my old shocks laying around. Haven't done anything with them. They worked fine before I removed them. My truck is a 2000 lx. Shocks had ~140,000 miles on them when I took them off. If you want em, I could probably ship em. I don't know how much new ones are, but it might save you some money.


...via IH8MUD app

 

[rustydrummer]

Although, I just noticed that you are in France...shipping across the pond might be pricey.


...via IH8MUD app

 

[super90]

One note on these instructions posted in the pdf files above.....

On Page 3, Step 5, I would highly recommend NOT trying to remove the "stabilizer bar brackets" from the frame. I had one of those bolts sheer off in the frame and had to weld the bracket to the frame later. Instead, disconnect the stabilizer bar (aka anti sway bar) from the bracket. Far easier and low risk.

I have no idea why the FSM recommends the procedure the way they do. It's not even the easiest way to do the job.

 

[uHu]

... The only reason I want to replace the shocks is that the outer casing is rusting and you can see the ram. the AHC is working prefectly with no leaks but I am a bit concerned that with the ram being exposed it will allow dirt to contaminate the outer seals. What I would like to know, what is the correct procedure for bleeding the system once I have fitted the new shock absorbers? Would there be an advantage of filling the shocks with oil thus reducing the amount of air getting into the system. I have read some stories where the shocks have been replaced and then had a great deal of trouble getting the system bled of air....

If the outer casing is the problem, you can fit new ones, stainless (aka Plastic). I used a standard plastic drainpipe of a suitable diameter - you'll prbly find the same size in France (eu standard - iso etc.). This can be done without removing the shocks, just take off the bottom mount, and remove springs (or whatever it was i removed ). Cut off remaining casing - leaving only the top sylindrical (straight) part. Cut a split (or 2) in the plastic pipe and slide it on, together with a hose clamp. You can use some weather profing around the top as a seal to prevent water running in through the split.

If you do take the shocks off, I think it is a good idea to fill them up. Might be a bit messy tho'.
In any case, take the opportunity to pump out all the old fluid, and replace with new. It's not possible to change all the fluid (what is inside the shocks) with a normal fill-and-bleed exchange.