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LS 430 rear left air strut


George86
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Hello. I hope some of you can help to solve the issue with my LS 430 year 2003. 
I park my car afternoon and until next morning the rear left suspension lower then the others, but only the rear left. I have replaced the level sensor on the buttom, but still the same, after a replaced the air strut as well, but still does the same. I have been in a garage they checked by computer, But did not show any trouble codes. If any of you have got any idea let me know please. Thanks you!

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You may have an air leak from one of the pipes leading to the strut. Spray soapy water on the connections and check for bubbles.

Is the replacement strut a new one? If it is used it may be faulty. The same question applies to the level sensor.

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You need to switch the engine on and put the suspension on the high setting, then switch the engine off. This should put air into the strut and raise that corner. Listen for the sound of air escaping. This may help to identify the leak.

I no longer have air suspension so I cannot remember how high the car will sit. It may be high enough for you to crawl under. If not, the car should be raised on ramps or axle stands for safety.

You need to check for a leak where the plastic air pipe goes into the strut. Another possibility is a leak at the rear height control valve. This is a junction of 3 pipes under the rear of the car, behind the differential and crossmember.

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Thank You. 
When I replaced the air strut I was checking for a leak with soapy water where the air pipe goes into the air strut, But there was alright.
And actually every morning when I start the car the air strut goes up so quick and stay there all day.

I will check this high control valve maybe there something wrong. 
 

And one more Thing, not long ago I have changed transmission fluid And actually the car since does this problem maybe in the garage during work accidentally damaged air pipe underneath of the car… is it possible?

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The fact that the strut rises quickly in the morning suggests that the air compressor is O.K. That is good news.

It sounds like air is leaking out from somewhere. I would have a close look at the pipes and connections.

Was the new height control sensor fitted in exactly the same position on the bracket as the old one?

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Thank you. 
yes, probably air leak, but where……. 😞 

yes I put it back exactly the same place where it was, I marked the place before I was removing. 

But I will check the rear hight control valve and all the connections as you said and just in case I gonna check the air pipes underneath of the car. 

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Hello. 

 I have checked the air pipe underneath of the car as much as I could. From front until rear level control valve solenoid It’s seems good….

After the control valve I could not check today (I had no time) But I just thinking, correct me if I’m wrong so: my issue is only the rear left air strut goes down from evening to next morning. 

If the air pipe would have a leak which is coming from front to rear control valve then both side air strut would goes down. Therefore I think that pipe from rear control valve to rear left strut have a leak somewhere, because if the control valve would be wrong then would goes down the right side as well, I think. 

  And one more Thing actually a quetion I have been computer diagnostic check and was not any fault code in the car system But still can be wrong the control valve or the computer would have been show if anything would be wrong? 

And one more Thing. The pressure sensor on the top of the air strut is can couse this problem, since was not any fault code. 

And that control valve can be half wrong I mean right side control is ok But left side not? 

Sorry for silly quetions I just want to sort out the problem. 

Thank you. 

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A leak between the height control valve and the strut seems logical as only one side is going down. 

When I had air suspension only one corner would drop overnight. My diagnostic kit showed no fault codes.

I don't know if the pressure sensor on top of the air strut could cause the problem. You could check by swapping the 2 pressure sensors over, starting the engine and letting the suspension rise before switching off. If the other side of the car drops overnight you have found the cause of the problem.

I have never dismantled the control valve so I don't know what is inside it. I am guessing that the valve for the rear left could be sticking partially open, or one of the O-rings may be allowing air to leak past very slowly.

They are not silly questions; they are based on logic.

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Thank You for Your answer. 
I will swap over those pressure sensors tomorrow and will see what will happen.

If not those pressure sensors are wrong then, have you got any idea how to check the control valve, that is it alright or not?  

And I using soapy water to spray onto pipe, but is not Really good. Is there any special spary to find leak? 
Thank you! 

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If you know a gas engineer or maybe spot one in the street a cheeky ask may get you some LDF ( Leak Detection Fluid) which bubbles from a leak and is easy to spot. Just spray it on and observe.

Or try Screwitfix.

8C92A1B5-E662-4014-A015-0F4DDB877F82.png

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Hi. 

I swapped over those two sensores, But unfortunetely is became a same, left side went down again. 
I have replaced everything exept the high control valve which is behind the differental. What do you think can this valve causeing this problem? 
I have got leak detector spray, I was spraying the air pipe from the control valve until air strut conection.  No leak, also sprayed the air strut and the whole control valve But no leak neither. 
What do you think is this control valve can be wrong like this I ,mean only wrong that  part which controlling the left side, is it possible?
Thank you. 
 

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On 9/25/2021 at 10:42 PM, Tomtit said:

A leak between the height control valve and the strut seems logical as only one side is going down. 

When I had air suspension only one corner would drop overnight. My diagnostic kit showed no fault codes.

I don't know if the pressure sensor on top of the air strut could cause the problem. You could check by swapping the 2 pressure sensors over, starting the engine and letting the suspension rise before switching off. If the other side of the car drops overnight you have found the cause of the problem.

I have never dismantled the control valve so I don't know what is inside it. I am guessing that the valve for the rear left could be sticking partially open, or one of the O-rings may be allowing air to leak past very slowly.

They are not silly questions; they are based on logic.

Hi.
I swapped over those two sensores, But unfortunetely is became a same, left side went down again. 
I have replaced everything exept the high control valve which is behind the differental. What do you think can this valve causeing this problem? 
I have got leak detector spray, I was spraying the air pipe from the control valve until air strut conection.  No leak, also sprayed the air strut and the whole control valve But no leak neither. 
What do you think is this control valve can be wrong like this I mean only wrong that  part which controlling the left side, is it possible?
Thank you. 
 

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I wonder if the rear height control valve is faulty and is allowing air to return from the strut to the front height control valve or to the compressor. Perhaps one of the O-rings has failed. It might be worth replacing the O-rings in the rear height control valve. I have not done this job. It is just a suggestion.

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From my experience of removing/replacing air struts on the LS, I know it's possible to fit the air pipe to the struts incorrectly, not seated property, which can cause a drop overnight, I've actually experienced this myself. It's also worth asking why you replaced the strut in the first place, was it because it was dropping on that corner, and did you buy a new, genuine Lexus part?

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1 hour ago, Tomtit said:

I wonder if the rear height control valve is faulty and is allowing air to return from the strut to the front height control valve or to the compressor. Perhaps one of the O-rings has failed. It might be worth replacing the O-rings in the rear height control valve. I have not done this job. It is just a suggestion.

Thank you. 

I will try this O- rings replace, because I have no more idea…

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59 minutes ago, The-Acre said:

From my experience of removing/replacing air struts on the LS, I know it's possible to fit the air pipe to the struts incorrectly, not seated property, which can cause a drop overnight, I've actually experienced this myself. It's also worth asking why you replaced the strut in the first place, was it because it was dropping on that corner, and did you buy a new, genuine Lexus part?

Hi.

is very good quetion. 🙂 

but first I was buying level sensors on both side, after still was the same. And then I went to computer diagnostic they said no any fault in car. And then I decided to buy the air strut…. But at least is new now 🙂

I will check the air pipe as you said and will see maybe is just an incorrect position….

thank you. 

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11 minutes ago, George86 said:

Hi.

is very good quetion. 🙂 

but first I was buying level sensors on both side, after still was the same. And then I went to computer diagnostic they said no any fault in car. And then I decided to buy the air strut…. But at least is new now 🙂

I will check the air pipe as you said and will see maybe is just an incorrect position….

thank you. 

It is possible to push the plastic air hose in without the "click" as it locates, and it will still be held in place enough to fill with air by the external white clip but create a slow leak.  At least the rear hoses are easier to get to than the fronts!  I've also seen the connection slightly damaged by disconnecting without the proper tool. It may only be a very small hose but it needs to be in perfect condition to make the airtight seal, which also means free of debris.

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Thank you. 
 

I think is alright i mean the Connection on the strat the pipe was click in. 
I have got leak detector spary and I sprayed the around and on the Connection and there is no leak…

but somewhere the air is disappear until tomorrow morning. Maybe do you know how money O- rings do I need? To replace all of them But only on the left side. Including the control valve as well maybe there is a leak But I was spraying with this leak detector and nothing ….. so if you have any idea Im sure is gonna help… 🙂 
thanks. 

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Thank you!  
What do you think about if I change over the two pipe in the control valve just to make sure is working alright…? I mean the left put into right and right put into left side and if the right side will go down then I will know that control valve does not work correctly… is it good idea? Or is it possible at all? 
thanks. 

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