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Changing Air Suspension Bladders

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I've been meaning to write this up for a while - about a year, in fact! Commonly, people repair worn Electronic Air Suspension (EAS) systems by replacing them with coil springs. While paying someone else to work on your EAS can quickly get expensive, if you don't mind getting your hands dirty it isn't that hard to work on. The most common problem is worn out bladders (the actual air 'springs'). Mind had done around 130,000 miles, which seems perfectly reasonably to me - coil springs would probably be getting a little tired by this point, too, and they're just as hard and more expensive to change.

There are two approaches you can take to replacing the air springs - replace the whole units, including the plungers, or replace only the rubber bladders. If you get it done at a garage, they'll do the former. It's less work, so if you're paying for labour there's no benefit to doing bladders only. If labour costs aren't an issue, you can buy a full set of bladders for around the same cost as a single complete unit - that's what I did, and what I've described here.

WARNING: The EAS system uses high air pressures - 10 bar or 150 psi. Goggles are essential fitting the new bladders, gloves advisable. If it all goes horribly wrong, that's your responsibility - this worked for me, and I didn't lose any body parts in the process, but you make your own decision as to the risks involved.

Raise the suspension to full height and support the chassis on axle stands - one each side, one under the front cross member, one under the rear. Make sure these are secure - your life depends on it!

Lower the suspension then disable it using the switch under the back of the right hand front seat. Disconnect the multiway connector from front of the EAS ECU (at the front under the same seat). Use wires to jumper across the multiway plug and open the outlet valve for each bladder to release any remaining pressure.

Unbolt the top (or bottom - but top is less likely to be rusted up...) of the dampers, then lower the axle as far as it will go. Take great care not to damage the height sensor by stressing it or turning it inside out. It may be worth unbolting one end of the sensor. We didn't, but see later...


A closer view of the deflated bladder. The height sensor can be clearly seen on the right, between the chassis and radius arm.


You can see just how badly my bladders needed to be replaced... :blink:

The construction is similar to that of tyres.


A close up of the worn out bladder. The area of severe wear is where the bladder folds over itself on the bottom plunger. It isn't obvious unless the suspension is at off-road height.


To business...

Obviously, the bladders aren't going to just fall off in your hands (well, it'd scare me if they did...). Put a foot on the end of the axle to push it down a bit further (again, watch that height sensor) then get a good solid lever behind the bladder and pop it off the top plunger.


Some of the bladders required a bit more persuasion. We levered them off the bead on the top plunger with a flat viscous fan spanner while pulling on the lever. Don't use anything which might damage the alloy plunger.


Once the bladder is free of the top plunger, plant a foot on the axle, grasp the bladder firmly and pull. Caution; you will go flying when it comes off, so check what's behind you!


The new bladder is an AirBagMan one, slightly longer than the original, but you can still clearly see how much the old bladder has deformed and shortened. It's also much less flexible than the new one (you can really feel the difference in the ride).

Obviously, these are front bladders.


Another view of the old and new bladders side by side. These are front bladders.


This shot is of the rear bladders, old and new.


It's fine to reuse the plungers - they should easily last the lifetime of the vehicle. Clean them up and dry them and they're ready for the new bladders to be fitted. This is the top plunger.


The bottom plunger will probably look a bit scruffier than the top one - as long as the bead the bladder sits on is in good nick, it should be fine.


Here, the photo's run out as we had our hands a bit full...you really need two people to fit the new bladders. One to actually fit the bladder and the other to operate the pump and air valves using jumpers across the ECU multiplug. Don't even think about reconnecting the ECU until everything else is sorted - it'll get confused and you'll end up handing your local land rover specialist a nice fat cheque just to plug it into a diagnostic computer and reset it. In any case, jumpering the multiplug gives you precise control of re-inflating the bladders, which you need.

Silicon lubricant is apparently great for refitting the bladders. I haven't tried that, but soapy water works just fine. Try not to get it inside the bottom plunger as you don't want moisture corroding the insides of your EAS system. The trick is to get the bladder sat as straight as possible between the pistons, position it so it seals against the pistons then one person holds it there while the second person opens the in valve using a jumper across the multiplug (remember to run the pump every now and then to keep air in the tank). The aim is to 'pop' the bladder onto the beads. Once you've seated both ends you need to get it to fold down over the bottom piston - try to prevent the bladder popping off to one side while gradually adding air. It's best to use your feet for this, partly because it's easier to apply enough force, partly because it keeps your face out of the way when the bladder blows off the plungers. Note when, not if - you'll go back to square one a few times before you manage to get the bladder properly seated. Very frustrating, but very satisfying when it finally pops into place.

Finally, raise the axle back up and bolt the damper back on. Take care that you don't turn the height sensors inside out, as you'll damage the potentiometer and the ECU will then generate a fault code and go into limp-home mode. This means it drops the vehicle onto the bump stops and refuses to do anything else until you drive to a land rover specialist and pay them substantial amounts of money to reset and recalibrate it with a diagnostic computer. Remember that jumper you were using on the multiplug? You can use that to inflate the suspension so you don't have to drive there on the bump stops. The potentiometer itself may repairable - take a look, because they're expensive for what they are.

As an added bonus, because the AirBagMan bladders are longer you can have your EAS set to ride higher when in off road mode - I think I've seen suggestions that they're good for and extra 1/2" to 1". I haven't done this, so I can't comment on whether it's worthwhile. It requires a diagnostic computer, so for most of us it's not a DIY job. More extreme lifts are available using alternate bladders or complete units - take a look at RangeRovers.net's EAS section, which has expanded quite a bit since I originally read up on this job on there :)

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