replacing AHC globes/accumulators (6 Viewers)

[Coin]

As I said above, my pressures were fine before yesterday. The rear is stock, no extra weight, and I replaced the rear springs 6-months ago. Whatever is causing the rear to not raise is also causing the rear pressures to be so high, even though the rear is sitting on the bump stomps. The front no longer raises as it did yesterday afternoon. The AHC Off light is now on.

I did think about the rear sensor, and will check it later, but that seems unlikely. I took it apart and cleaned it when I flushed the AHC fluid 6-months ago. It looked brand new inside.

 

[IndroCruise]

As I said above, my pressures were fine before yesterday. The rear is stock, no extra weight, and I replaced the rear springs 6-months ago. Whatever is causing the rear to not raise is also causing the rear pressures to be so high, even though the rear is sitting on the bump stomps. The front no longer raises as it did yesterday afternoon. The AHC Off light is now on.

I did think about the rear sensor, and will check it later, but that seems unlikely. I took it apart and cleaned it when I flushed the AHC fluid 6-months ago. It looked brand new inside.

Symptoms:

• Vehicle on rear bump stops,
• Front normal,
• Height Control Sensors considered sound,
• Control Valve Assembly considered sound according to solenoid resistance measurements,
• Rear pressure showing 9Mpa (as measured by pressure sensor at AHC pump) but vehicle refuses to lift stock weight and no load,
• External possibility: something jamming suspension, impeding lift – seems unlikely, already would have been noticed by Owner,
• Internal possibility: jammed valve or blockage in Levelling Valves in Control Valve Assembly (unusual – but certainly possible even though solenoid resistances are OK), or, blockage elsewhere in the line.

Despite efforts to bleed, some old fluid remains, and ‘gloop’ can form – see pics at Post #67 and later posts at:
AHC pump out? - https://forum.ih8mud.com/threads/ahc-pump-out.1226629/page-4#post-13401098

Suggested possible actions to consider:

• Listen/feel for actual operation of Levelling Valves when a raise is attempted,
• Monitor valve operation on Techstream during a raise (“SLRL”= Solenoid Rear Levelling, “SLFL” = Solenoid Front Levelling Valve, “SLAC” = Solenoid Height Accumulator Valve). However, this only indicates the instructions given by ECU and may not represent what is actually happening at the valves, especially if jammed or partially blocked,
• Bleed both sides at Rear in effort to clear blockage (if there is one) – which also should relieve pressure,
• Use a pressure gauge such as LSPV gauge to measure actual Rear AHC pressure, check whether it is consistent with pressure at AHC Pump (after allowing for 1.2 Mpa difference per FSM). If pressure as measured at AHC Pump by Techstream is 9 Mpa but actual pressure at ‘Rear’ ‘globe’/actuator by pressure gauge is much less, then that would suggest blockage or defect in the line between AHC Pump and Rear ‘globe’/actuator – this may lead to suspicion about Levelling Valve blockage or defect within the Control Valve Assembly despite healthy solenoid electrical resistances, and/or, suspicion about blockage or defect in one or both Damping Force Control Actuators (maybe worthwhile checking resistances here as well).

 

[Coin]

Suggested possible actions to consider:

• Listen/feel for actual operation of Levelling Valves when a raise is attempted,
• Monitor valve operation on Techstream during a raise (“SLRL”= Solenoid Rear Levelling, “SLFL” = Solenoid Front Levelling Valve, “SLAC” = Solenoid Height Accumulator Valve). However, this only indicates the instructions given by ECU and may not represent what is actually happening at the valves, especially if jammed or partially blocked,
• Bleed both sides at Rear in effort to clear blockage (if there is one) – which also should relieve pressure,
• Use a pressure gauge such as LSPV gauge to measure actual Rear AHC pressure, check whether it is consistent with pressure at AHC Pump (after allowing for 1.2 Mpa difference per FSM). If pressure as measured at AHC Pump by Techstream is 9 Mpa but actual pressure at ‘Rear’ ‘globe’/actuator by pressure gauge is much less, then that would suggest blockage or defect in the line between AHC Pump and Rear ‘globe’/actuator – this may lead to suspicion about Levelling Valve blockage or defect within the Control Valve Assembly despite healthy solenoid electrical resistances, and/or, suspicion about blockage or defect in one or both Damping Force Control Actuators (maybe worthwhile checking resistances here as well).

Thanks!
I'm thinking there is a blockage.

Right now I can't check the first two items on your list. AHC Off light is on, and it won't turn off.
I just ordered a new set of globes, since I know I need them anyway. When swapping them out, hopefully any gunk stuck in the system is dislodged during the fluid bleed.
If after replacing the globes/fluid I still have this issue, I'll look into getting a gauge and checking the last bullet point items.

 

[Coin]

I replaced all 4 globes last night. I purchased them off ebay, as I needed them sooner rather than later. After a full fluid flush and figuring out I needed to hold the AHC "off" button down a few seconds to reset it, the truck raised and drives like I'm floating on a cloud. I went from transitioning through about 6-7 lines of fluid in the AHC reservoir before the globes failed to now having 10 or more. I didn't bother counting, it was pretty much the range of the entire scale on the side of the reservoir.

I had flushed the fluid about a year ago, but it was already dark and foamy. I suppose a symptom of the failing globes.

For any of you guys out there with 6-7 lines of transition, replace the globes. It's worth it! I wish I had done it sooner.

 

[tjb]

For any of you guys out there with 6-7 lines of transition, replace the globes. It's worth it! I wish I had done it sooner.

It is fun to do a maintenance/repair job that results in immediate positive feedback.

 

[rdsmvp]

I replaced all 4 globes last night. I purchased them off ebay, as I needed them sooner rather than later. After a full fluid flush and figuring out I needed to hold the AHC "off" button down a few seconds to reset it, the truck raised and drives like I'm floating on a cloud. I went from transitioning through about 6-7 lines of fluid in the AHC reservoir before the globes failed to now having 10 or more. I didn't bother counting, it was pretty much the range of the entire scale on the side of the reservoir.

I had flushed the fluid about a year ago, but it was already dark and foamy. I suppose a symptom of the failing globes.

For any of you guys out there with 6-7 lines of transition, replace the globes. It's worth it! I wish I had done it sooner.

Great it solved it! How hard is it to replace the globes?

CR

 

[Coin]

Piece of cake. The 36mm wrench I borrowed from the parts store was a bit rounded, so I used the chisel and hammer method to knock them loose. Then they twisted off by hand. I was able to used the wrench to snug up the globes without rounding them off.

Granted I live in Texas and my truck has zero rust.

 

[Weasel06]

This was a great read. Thanks to all that have contributed. I recently replaced both front and rear shocks and did an AHC flush and put her within spec per Techstream. Seemed to ride pretty well for a couple weeks, but now she seems bothered by every little imperfection in the road. I'm now going to replace front/rear bushings and I just made the leap of faith and ordered accumulators from IMPEX. I hope to be floating on that cloud by the end of the month.

 

[tjb]

but now she seems bothered by every little imperfection in the road.

I have this same sense … and I’ve done a lot of the bushings.

 

[Weasel06]

I have this same sense … and I’ve done a lot of the bushings.

Are you saying that you're still not happy with the ride after all you've done?

 

[tjb]

Are you saying that you're still not happy with the ride after all you've done?

No, I’m very happy. It’s just that it feels a little harsh at times. Almost like something in the control system isn’t working right at times. I haven’t focused enough on it to know whether my perception that ‘sometimes it‘s great, sometimes it’s harsh’ would hold up to scrutiny. Just threw it into the thread to see if it triggers some thought from others.

 

[super90]

This was a great read. Thanks to all that have contributed. I recently replaced both front and rear shocks and did an AHC flush and put her within spec per Techstream. Seemed to ride pretty well for a couple weeks, but now she seems bothered by every little imperfection in the road. I'm now going to replace front/rear bushings and I just made the leap of faith and ordered accumulators from IMPEX. I hope to be floating on that cloud by the end of the month.

I ordered from IMPEX. It was a little fussy and you had to pay attention to their messages and shipping etc., but the globes arrived. Still haven't had time to install. And it is not officially HOT in Texas.

 

[flintknapper]

I ordered from IMPEX. It was a little fussy and you had to pay attention to their messages and shipping etc., but the globes arrived. Still haven't had time to install. And it is not officially HOT in Texas.

^^^^

Yeah, but its coming!


Got pretty warm today.

 

[halbeezy]

I ordered from IMPEX. It was a little fussy and you had to pay attention to their messages and shipping etc., but the globes arrived. Still haven't had time to install. And it is not officially HOT in Texas.

Did your globes arrive yet?

 

[Weasel06]

My globes arrived today. I placed the order on 6/9, so two weeks exactly from order to receiving. My total cost via Paypal turned out to be $708.37, which must include various fees from the credit card I used because the yen to dollar conversion doesn't match. There were three transactions. One for the globes, one for shipping and then an additional $1.90 in shipping. Tracking this transaction from the IMPEX website and via FedEx tracking was okay. The information was slow coming and a little late, but I did feel comfortable that the order was going through as planned. Now I'm waiting on the AHC fluid from McGeorge to arrive.

 

[halbeezy]

My globes arrived today. I placed the order on 6/9, so two weeks exactly from order to receiving. My total cost via Paypal turned out to be $708.37, which must include various fees from the credit card I used because the yen to dollar conversion doesn't match. There were three transactions. One for the globes, one for shipping and then an additional $1.90 in shipping. Tracking this transaction from the IMPEX website and via FedEx tracking was okay. The information was slow coming and a little late, but I did feel comfortable that the order was going through as planned. Now I'm waiting on the AHC fluid from McGeorge to arrive.View attachment 2712005

I am literally doing the exact same thing as you in including where you purchased your ahc from. Can I ask how many bottles of ahc did you buy?

 

[Weasel06]

I am literally doing the exact same thing as you in including where you purchased your ahc from. Can I ask how many bottles of ahc did you buy?

I used 3 bottles when doing a flush earlier this year, but I bought 4 bottles for this change out in the event that I need to bleed out any air that may get in the system.

 

[halbeezy]

I used 3 bottles when doing a flush earlier this year, but I bought 4 bottles for this change out in the event that I need to bleed out any air that may get in the system.

how is the ride now since changing the globes?

 

[BigGreenLX]

Any chance you guys could include a link to IMPEX. I wound up on a page in Russian

 

[halbeezy]

Any chance you guys could include a link to IMPEX. I wound up on a page in Russian

49151-60010 TOYOTA , 4915160010 New parts search — IMPEX JAPAN

en.impex-jp.com