Front AHC Shock Leak (1 Viewer)

[benn]

Hello all,
Looking for a few opinions on this. I went camping this weekend, parked the LX Friday and didn't move it all weekend, came out Sunday morning and it looked like this;

The front was noticeably lower and there was a big puddle of AHC oil just behind the front passenger tire. After packing up, the AHC initially showed "off" but then went into L for the 30 minute drive home. After parking at home, the reservoir was empty and more fluid leaked out.

There was fluid everywhere in the wheel well and along the frame/lines/undercarriage right side and I wanted to try and find the leak. It didn't look like it had been spraying at high pressure anywhere, but dripping/running back from the driving, so I assumed highest/most forward. I added about a quart of AHC fluid, cleaned up the shock area and started the car. It raised to N and stopped blinking. I shut the car off, noticed fluid was dripping down the shock tube on the back side from the top cushion area.

It isn't leaking from the connection on top, but from the top of the shock/hydraulic ram.

I just flushed the AHC fluid a few weeks ago for regular maintenance and here were my readings;

so, I was feeling pretty good about the system. 2003 LX470 with 155k miles. Bought in 2016 with 83k. Some surface rust on the undercarriage, but I try to keep it fluid filmed.

Looking for some advice here;
1. Do you think I damaged the pump driving home? Reservoir was empty on arrival, but the system did lift the vehicle and go back into N after I added fluid and started up.
2. Looks like a new AHC "shock" with associated bushings, retaining nuts, etc... will run about $400. plus another $140 or so in AHC fluid once complete. Unless there is something I'm missing, like only the cushions or top part can be replaced? I assume the whole assembly needs replace but please correct me.

-What are your thoughts on replacing this "shock" and keeping the systems vs tearing out for a conventional setup?

I know there are AHC purists out there and those that tear it out. I plan on keeping this whip for the foreseeable future, just looking to keep it reliable and running. I don't mind messing with the AHC, I just hate to think if this would have happened 600 miles from home. The only issue I've had before with the AHC was a bad height sensor a few years back, which was pretty easy to troubleshoot with help from you folks. Thoughts on fixing vs cutting my losses and going conventional?

Thanks,
Ben

 

[suprarx7nut]

Ben,

1. No. Damage is unlikely.
2. Yes, I would replace the shock, O-ring, back up seal and the cushions (there are two).

Definitely keep AHC. Just replace the shock, and re-assess from there. You'll spend way more $$ on a conversion and then you've lost one of the best parts about the LX.

Total seal failures like this are unusual. I see it's got real low mileage. Perhaps it sat for many years at a time and the seal dry-rotted?

When you go to do the repair, keep that fluid reservoir full. Purging air can be a chore when the job is done.

 

[hoser]

Leak near top of Front Driver AHC Shock

I noticed a leak that appears might be originating near the top of the front driver side AHC shock. It seems to proceed down to the location in the second photo. I've done an AHC pressure test and get 8.1 in the front. I will pick up a 30mm socket and adjust my torsion bars tomorrow in case...

forum.ih8mud.com

 

[benn]

Ben,

1. No. Damage is unlikely.
2. Yes, I would replace the shock, O-ring, back up seal and the cushions (there are two).

Definitely keep AHC. Just replace the shock, and re-assess from there. You'll spend way more $$ on a conversion and then you've lost one of the best parts about the LX.

Total seal failures like this are unusual. I see it's got real low mileage. Perhaps it sat for many years at a time and the seal dry-rotted?

When you go to do the repair, keep that fluid reservoir full. Purging air can be a chore when the job is done.

Thanks for the feedback. Hasn't sat for more than a few days since I've owned it the last 7-8 years. Original owner was in PA/VA, I've had it in VA/IN so it does have some corrosion on the underside.

My thinking is that if this failed, are the other shocks, globes, etc... on the verge of failing just due to age/wear at this point on a 20+ year old truck? Sounds like your opinion is that this is likely a one-off and that there still should be useful life left with a repair? Thanks again for your thoughts and tips on the repair.

 

[benn]

Leak near top of Front Driver AHC Shock

I noticed a leak that appears might be originating near the top of the front driver side AHC shock. It seems to proceed down to the location in the second photo. I've done an AHC pressure test and get 8.1 in the front. I will pick up a 30mm socket and adjust my torsion bars tomorrow in case...

forum.ih8mud.com

Thanks for the link. Definitely good info if I get into replacing the shock and associated hardware. Thanks again.

Ben

 

[wrigh003]

Im not a purist per se but I do like AHC, and it’s holding up pretty well for me in some pretty hairy off-road situations. The ride for the 95% of the time you’re driving the truck around town is the thing, though, and I’d hate to lose that, so here’s another vote for “just fix it and roll on.” $400ish is still less than half of the cheapest static lift anyway.

I’ll add- a $30 air powered brake bleeder from Amazon REALLY helps get the air all out. I don’t know that I’d ever have gravity bled it all out, when I replaced my globes mine had a TON of bubbles come out, and I suspect a lot of that was in the lines out to the hydraulic rams and the rams themselves.

Edit: check your pressures and stuff via techstream. There’s an “ABCs of AHC” thread on here that’s very useful. If you need globes too, that’s another few few hundred bucks, but $1000ish for the truck as engineered by Toyota vs an aftermarket option? Still better to me.

 

[Rhetoric]

Looks like you got some extra “free” AHC fluid undercoating there!

Honestly since your truck isnt a rust pile I would replace the shock and motor on. You can check graduations in the reservoir to verify globe health and assess if you need those.

 

[benn]

Thanks all for the replies/input. I went ahead and ordered a new shock and hardware/o rings/cushions to go with with it. I'll update once complete.

 

[Wilsil]

A new shock can't be $400.
I was quoted last year AUD$170

 

[GremlinMobile]

Im not a purist per se but I do like AHC, and it’s holding up pretty well for me in some pretty hairy off-road situations. The ride for the 95% of the time you’re driving the truck around town is the thing, though, and I’d hate to lose that, so here’s another vote for “just fix it and roll on.” $400ish is still less than half of the cheapest static lift anyway.

I’ll add- a $30 air powered brake bleeder from Amazon REALLY helps get the air all out. I don’t know that I’d ever have gravity bled it all out, when I replaced my globes mine had a TON of bubbles come out, and I suspect a lot of that was in the lines out to the hydraulic rams and the rams themselves.

Edit: check your pressures and stuff via techstream. There’s an “ABCs of AHC” thread on here that’s very useful. If you need globes too, that’s another few few hundred bucks, but $1000ish for the truck as engineered by Toyota vs an aftermarket option? Still better to me.

Can you elaborate on what kind of air powered bleeder you're talking about and how you use it? I bought one of those hand pump bleeders with a guage and tubing. I couldn't make it useful even for bleeding my brakes. Ended up just enlisting my wife to pump the pedal and bleed it that way.

But with AHC, how do you use it? My issues is that I have a never ending supply of AHC fluid with air entrapped in it on the passenger side. I can only bleed so much until the car is on bump stops. Does your method alleviate this issue?

 

[suprarx7nut]

Thanks for the feedback. Hasn't sat for more than a few days since I've owned it the last 7-8 years. Original owner was in PA/VA, I've had it in VA/IN so it does have some corrosion on the underside.

My thinking is that if this failed, are the other shocks, globes, etc... on the verge of failing just due to age/wear at this point on a 20+ year old truck? Sounds like your opinion is that this is likely a one-off and that there still should be useful life left with a repair? Thanks again for your thoughts and tips on the repair.

If it lived in the east, it might have more rust, but usually that's immediately visually apparent. I'd replace a few rams before I gave up on the system.

Can you elaborate on what kind of air powered bleeder you're talking about and how you use it? I bought one of those hand pump bleeders with a guage and tubing. I couldn't make it useful even for bleeding my brakes. Ended up just enlisting my wife to pump the pedal and bleed it that way.

But with AHC, how do you use it? My issues is that I have a never ending supply of AHC fluid with air entrapped in it on the passenger side. I can only bleed so much until the car is on bump stops. Does your method alleviate this issue?

If you have perpetual air entrapped on one side that's a giveaway that a globe is worn out and due for replacement. ~$600-700 for a set of 4.

 

[GremlinMobile]

If it lived in the east, it might have more rust, but usually that's immediately visually apparent. I'd replace a few rams before I gave up on the system.


If you have perpetual air entrapped on one side that's a giveaway that a globe is worn out and due for replacement. ~$600-700 for a set of 4.

How can it be perpetual? The globe is pre-charged with a finite amount of nitrogen. At some point, it all gets bled out and the nitrogen part of the globe gets filled with fluid.

 

[suprarx7nut]

How can it be perpetual? The globe is pre-charged with a finite amount of nitrogen. At some point, it all gets bled out and the nitrogen part of the globe gets filled with fluid.

Eventually, yes. haha. It's ~700 psi. That's 50 times atmospheric. That's a LOT of volume to work through. You could have gas entrainment for years from one bad globe slowly releasing gas.

 

[benn]

A new shock can't be $400.
I was quoted last year AUD$170

You're right, the shock isn't $400, paid $242 for the shock, ($204 from McGeorge) but for everything it was right around $400.
Here is what I ended up going with from Lexus of Oxnard Parts. Slightly more expensive than McGeorge (now Ourisman Toyota of Richmond Parts) but Oxnard is offering free shipping so total cost is about the same. May not have needed some of the hardware, got multiples of some of the seals/cusions but figured it was good insurance to have everything on hand once it is apart. Thanks again for all the feedback everyone.

P/N​	Quantity​	Price Each​	Description​
9008011232​	4	$ 1.27​	Suspension Stabilizer Bar Bracket Bolt
9017914045​	1	$ 2.34​	NUT
9011914093​	1	$ 5.41​	BOLT, WITH WASHER
9094801076​	1	$ 17.38​	CUSHION, FRONT SHOCK ABSORBER, NO. 2
9094802182​	1	$ 16.98​	Suspension Shock Absorber Mount Washer (Front)
4859760020​	1	$ 11.96​	RETAINER, SHOCK ABSORBER CUSHION
4859760021​	1	$ 11.34​	RETAINER, SHOCK ABSORBER CUSHION
9090389016​	1	$ 20.63​	Suspension Shock Absorber Mount Bushing (Front)
9017716001​	1	$ 2.13​	Suspension Shock Absorber Nut
9671119009​	1	$ 2.76​	Fuel Injection Idle Air Control Valve Gasket
9030111022​	2	$ 3.80​	RING, O
9056212003​	2	$ 2.87​	RING
9056209005​	2	$ 2.35​	RING
9094801075​	1	$ 27.08​	Suspension Shock Absorber Mount Bushing (Front)
9094802183​	1	$ 21.37​	RETAINER CUSHION, NO. 1(FOR FRONT SHOCK ABSORBER); CUSHION, NO. 2(FOR REAR SHOCK ABSORBER).
4851069127​	1	$ 242.36​	Suspension Shock Absorber (Left, Right, Front) SHOCK, FRONT LEFT; SHOCK, FRONT RIGHT.

---

Order Summary:

16 product(s) , 22 item(s)​	$ 404.86​
Coupon​	- $ 98.39​
Shipping & Handling​	$ 98.39​
Total:​	$ 404.86​

 

[GremlinMobile]

Eventually, yes. haha. It's ~700 psi. That's 50 times atmospheric. That's a LOT of volume to work through. You could have gas entrainment for years from one bad globe slowly releasing gas.

How to test the theory that one or more of the globes are leaking gas without prophylactically replacing globes?

 

[suprarx7nut]

My approach:

1. Do the grad test. It's fast and free.
1z (optional): If globes are known to be beyond ~8 years old, replace them all. They're wear items.
2a. If grad test fails, replace all of them.
2b. If grad test passes, pay attention to which corner has the most gas. Replace that globe. Bleed until no gas at all.
3. Check for gas again. If any exists, replace the next most "gassy" corner.
4. Repeat as needed.

The globes generally last 5-10 years. When they completely die they will feel *awful*. Before they're totally dead, they'll just feel increasingly harsh and release gas into the system which makes the system harsher all over.


Globes are relatively cheap and easy to replace. Cheaper and easier to replace than traditional shocks (pending how you value labor time).

 

[wrigh003]

Can you elaborate on what kind of air powered bleeder you're talking about and how you use it? I bought one of those hand pump bleeders with a guage and tubing. I couldn't make it useful even for bleeding my brakes. Ended up just enlisting my wife to pump the pedal and bleed it that way.

But with AHC, how do you use it? My issues is that I have a never ending supply of AHC fluid with air entrapped in it on the passenger side. I can only bleed so much until the car is on bump stops. Does your method alleviate this issue?

ARES 70923-1-Liter Vacuum Brake... Amazon.com - https://www.amazon.com/dp/B07CP1YLDF?ref=ppx_pop_mob_ap_share

That’s what i have. You just pull the trigger, make sure the end is on the bleeder screw, crack the bleeder open and it sucks the air out. More air will come than fluid, so eventually it gets it all. If you feel like being extra you can make a mark on the jug so you don’t over-bleed before you can get up there to top up.

I tried to gravity bleed mine for hours before I knuckled under and bought that thing. Works good on brakes too.

 

[IndroCruise]

How to test the theory that one or more of the globes are leaking gas without prophylactically replacing globes?

In addition to the practical approach by @suprarx7nut in his Post #16, here are a few further details which may or may not help with "prophylaxis" ....

The membranes inside the 'globes' flex constantly whenever the vehicle is travelling, as AHC Fluid passes to and from the so-called 'shock absorbers' which on an AHC-equipped vehicle really are just hydraulic struts with very little, if any, damping function.

On an AHC-equiped vehicle, damping occurs by controlling the flow rate of the AHC Fluid to and from these struts.

Controlling the rate of flow of the AHC Fluid between components is the function of the Damping Force Control Actuators to which the 'globes' are attached. These Damping Force Control Actuators in concert with the ECU provide continuously variable flow rates (and hence damping) in real time across 16 steps governed by the internal step motor and valve settings in response to road conditions and the driver's settings on the centre console.

The 'globes' themselves are described in the FSM as gas springs because this is exactly what they are -- springs which depend on compression and expansion of gas (nitrogen) enclosed between the steel shell and the flexible membrane. The 'globes' act jointly as springs with the Rear coils and the Front torsion bars. The 'globes' by themselves are not Shock Absorbers. If there were no Damping Force Control Actuators (or if an Actuator fails), leaving only the 'globes' in place and functioning, then there would be no damping (or very little damping) at that position and a VERY 'springy' ride.

The resin membrane in the 'globe' is sandwiched between rubber layers to enable good resistance to gas penetration. The internal pressure of the nitrogen within the ‘globe’ is varied by the Damping Force Control Actuator allowing AHC Fluid to flow in and out of the fluid side of the ‘globe’. Further details are shown below:

Age and continued flexure -- particularly near the perimeter of the membrane where it joins the steel shell -- mean that the membrane slowly and steadily becomes more permeable. Nitrogen passes across the membrane to the fluid side. The AHC Fluid slowly fills the space on the gas side of the membrane.

There is no provision to enable direct measurement of the nitrogen pressure or nitrogen content in an LC100/LX470 'globe'.

The "HI/LO" test which measures the volume of AHC Fluid displaced to the AHC Tank at LO height compared to HI height provides a diagnostic indicator of the overall 'globe' condition. When this test it is done consistently at FSM-specified vehicle height and FSM-specified AHC (fluid) pressure ranges, the volume displaced by the 'shock absorbers' due to the height change remains constant. The measured changes in the volume of AHC Fluid displaced to the AHC Tank in successive tests over the years (indicated by the changes in the number of graduations observed at the AHC Tank) is then due to the declining volume pushed back to the AHC Tank by the reduced amount and pressure of nitrogen behind the steadily deteriorating membranes in the AHC 'globes'. This provides an indication of the overall condition of the four 'globes'. This test does not reveal the condition of individual 'globes'.

Based on IH8MUD Member experiences and reports over the life of 100 series vehicles with AHC, manufactured between 1998 and 2007, the reduction from ~14 graduations (all 'globes' are as new) to ~7 graduations (consider all 'globes' worn-out -- replace) may take around 10 years, some more, some less. The youngest vehicles are 17 years old, and would be expected to be on their second set of 'globes' and some may even be considering their third set. These are 'wear items' like any other 'wear items' such as other suspension parts, brake components, conventional shock absorbers, tyres, etc, etc, on any vehicle.

If the volume of AHC Fluid displaced under 'standard or comparable conditions' has halved over time (from 14 graduations to 7 graduations), it might be reasonable to assume that the volume of the original nitrogen also has halved.

What will be clear is that damping effeciveness and 'ride comfort' will have deteriorated significantly -- and will become steadily more harsh as test readings decline towards 7 graduations over the years compared to new 'globes' at ~14 graduations.

As already mentioned by @suprarx7nut, observation of gas streams at individual 'globes' may give an indication of the likely condition of an individual 'globe'. The so-called '16 step test' performed at each corner also may be helpful -- although it does not by itself distinguish between a 'globe' problem and an 'actuator' problem -- see "Damping Force Controlling Condition Check" at Page 5 of the attachment provided long ago by @PADDO.

Obviously, all 'globes' may not fail at the same time. Differences at manufacture and pressurisation at the factory may exist However, it is likely that if one or more 'globes' fail, then the others are not far behind, so replacing all four 'globes' at the one time is the wise course of action.

Also consider for an additional ~USD100 (ex-IMPEX plus delivery) replacement of the AHC Pump sub-assembly 48901-60010 and relevant seals while the AHC system is already disrupted for the 'globe' change.

48901-60010 – AHC Pump sub-assembly,
90311-10001 – oil seal between AHC Pump and Motor,
90301-70003 – large O-ring for AHC Pump outer cover of AHC Pump,
90301-06012 – small O-ring for discharge from AHC Pump sub-assembly to AHC system,
47255-60010 – grommet between AHC Tank and AHC Pump,
49189-60010 – replacement bleeder valves (5 required),
49177-60010 – replacement bleeder caps (5 required),
08886-01805 – AHC Fluid in 2.5 litre steel drums, at least two, probably three drums,

 

[benn]

Received parts and swapped out the shock/hardware yesterday. Swapped the parts, bled the system, no leaks, and its riding smooth.

Special thanks to @suprarx7nut for advice and this post with the FSM Procedure for shock replacement


Also thanks to @2001LC for this picture detailing the o-ring location

Old cushions were pretty rough

New

Another shot of the o-ring inside of the housing that connects to the top of the shock, for anyone else searching this item.

Thanks again all.

Ben

 

[suprarx7nut]

Received parts and swapped out the shock/hardware yesterday. Swapped the parts, bled the system, no leaks, and its riding smooth.

Special thanks to @suprarx7nut for advice and this post with the FSM Procedure for shock replacement


Also thanks to @2001LC for this picture detailing the o-ring location

Old cushions were pretty rough
View attachment 3681923

New
View attachment 3681924
Another shot of the o-ring inside of the housing that connects to the top of the shock, for anyone else searching this item.
View attachment 3681925

Thanks again all.

Ben

Fantastic work. Did you get a good shot of the piston right around that o-ring? The part that's right behind your old bushing. I wonder if that's pitted and corroded and led to the leak.

Makes me want to get mine done...