Testing air suspension for leaks?

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Nechaken

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The workshop manual for the Vehicle Dynamic Suspension is a good read, thanks. It refers to a High Speed mode where the suspension is dropped when it detects 100 MPH. Does anyone know what year this feature was introduced?

High Speed Mode
In later software a high speed mode is introduced. High speed mode is a non-selectable, automatic mode which lowers the vehicle
height by 20 mm to improve vehicle handling. This feature is fully automated and is 'invisible' to the driver.
If the vehicle speed exceeds 100 mph (160 km/h) for more than 5 seconds, the air suspension control module initiates the high
speed mode. When the vehicle speed reduces to less than 80 mph (130 km/h) for more than 30 seconds, the vehicle returns to
'on-road' height. This function is cancelled if a trailer is connected to the trailer socket.

The thought of an LR4 on the autobahn is utterly terrifying.
 

powershift

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My LR4 has been up to 110 MPH in a straight line and it was smooth as butter. Plenty of speed left on the table. In 4th gear punching a hole in the air at that speed the wind resistance gives the engine a good workout, like running a dog at the lake. If its going to have a heart attack it would do it then, ask me how I know :D.
 

Nechaken

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I've done 100+ in mine before as well on straight roads. It's smooth, its stable, but get above 90 and you realize any kind of animal avoidance maneuver might not leave you shiny side up. May not help that I have 18" all-terrains, either.
 
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powershift

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The owners manual explicitly states its top heavy and it will roll over if you do it wrong. On the highway I travel over a mountain pass and when taking a set for a corner there is a lot of body movement before it settles. I haven't read that warning in any of my previous vehicles but this is my first SUV. There are some good warnings in there, one that I learned on the race track and that is when you join the road from the dirt you could do it wrong and lose control of the vehicle.

Aside from that I've been tracking my air leak and it reproduces every couple days where the rear RHS seems to drop more than the rear LHS. When I fired up the engine the door is open and then once I was near the RR exterior the door was shut then I saw the RR raise up an inch or more.
I found a YT vid where a guy replaces the rear strut. It seems like a straight forward no-nonsense job and my indy wanted over $1,000 for labor to do strut replacements in the rear. I originally thought maybe the leak was a valve block, but I have no experience with air suspensions and since it didn't squat evenly I thought maybe it was a shock that is leaking. How are shock vs. valve block isolated to determine which part is not functioning anymore?

Here is the vid I found, this guy is no-nonsense and gets it done. He mentioned torqueing the lower strut bolt when the body is settled. I hadn't thought of doing that. Is there any purpose to it? I was just going to torque the bolts while in the air.
 

ugmw177

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Torquing the bolts once settled makes sure the bushing(s) do not have a twist on them for normal riding position as they will not last very long in that bound position. When i ususally do this, i have a jack stand under the frame and then use a hydraulic jack under the control arm and jack up the suspension until it is at estimated normal height.
Yes, changing the air shocks is pretty easy.

To isolate the rear, leave at normal height, pull the EAS fuse and leave the car overnight. if both rears drop the same amount, suspect the rear block. if one or the other side drops more, suspect the bag on that side or air line or connections--these can be checked by sraying fairy soap all over the connections and look for bubble production.
 

Jimmy Brooks

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I’ve had arnott struts on the front of my rig since about 90k- 100k. Probably almost for 6 years now, they’ve been great. Rears are original, won’t be replacing them till I hear an air leak like I did with the fronts.

My compressor is also arnott, had it since 80k, it’s been great as well, probably closer to 7 years now.

Vehicle is at mid 147k
 

powershift

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Sounds like a good experience with Arnott overall and their compressor sounds impressive.

After reading some Range Rover posts about air struts and leaks now I''m debating whether I have a leak. Some people are saying that unless it isn't on the bump stops in the morning it isn't a leak. My last measurement was a 5/16" drop in 24 hrs.

It seems like if I can identify an actual leak in the strut then it makes sense to replace it before it gets worse. I was reading that winter brings out leaks and I'm planning for winter now lol. But on the other hand if 5/16" is normal settling or leaking then replacing the strut would be a pointless exercise.
 

Longtrail

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Is it one side or the other or both sides? Don't rule out the rear valve, a leak in one of the three valves could result in one side lowering, you need to look at the pneumatic diagrams to understand how the three valves in the one valve block work.
 

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