Suspension, what am I doing wrong?

[Nomad9]

Hi There,
I had a problem with my valve block, not related, just carrying out some maintenance and my exhaust, repaired the valve block, fixed the exhaust, all good. I dropped the car to the floor and started the engine, three of the air bags inflated and where fine. After a while I heard a loud whoosh from the rear left wheel, found the air bag deflated.

Took the air bag out and found the top plastic section dislodged, got some washing up liquid and replaced, again lowered to the floor, partially inflated the bag by opening and closing the rear passenger door, got the bag partially inflated but still noticed a crease in the bag, lowered the car to the floor, the bag creased over, again the bag suddenly deflated this time the bottom flange dislodged. Again I removed the bag and have replaced the plastic end flange in the bag. Before I have another go is there something here I am doing wrong when lowering the car to the floor?

What procedure should I follow, is there one? I'm sure lots of people replace the air bags and don't have this problem. Engine running, engine not running, wheel off the floor, wheel on the floor on the bump stops?????

help........... Thanks in anticipation.

[Keithy P38]

G'day Nomad!

I'm going to assume you are running OEM airbags in your Rangie?

A few questions before I fire off answers!

When you are lifting your Rangie off the ground, are the diffs hanging from the springs, or are they being supported during jacking/hoisting?

Are the bags new or old (what condition)?

One of the issues with jacking a P38 is that the bellows will pull off the pistons if they are left to hang when the vehicle is on a hoist or axle stands under the chassis. Standard shocks are enough to rip Arnott Gen III springs to bits, so standard springs will be quite stretched at full droop.

Cheers
Keithy

[Nomad9]

Hi Keithy,
Ok, so the car is on a hoist supported by the chassis, I can remove and replace the bag quite easily in this situation, the bags as far as I know are standard, they are Dunlop ones bought from Eurospares in the UK, the date stamp on the top is 06 13 which I assume is June 2013 so they are quite new, they look new. The shocks are standard, again as far as I can tell. The right hand bag is fine, inflated perfecttly. I think I have been letting the vehicle back onto the wheel/tyre to early with not enough pressure in the bag, hence the creasing and "popping" off.

I'll wait to see what you suggest, I can see what you are talking about when I look underneath, there must be a fine line between right and very wrong.

My intention this afternoon when I get home is to install the bag, start the engine with the car on the hoist, wheels off the floor and let things run until the compressor stops. If the right hand side bag is OK I can't see any rhyme or reason why the left hand bag shouldn't be the same.

I'll wait and see what you or others come back with. My mistake was when I fixed the valve block and the car was on the bumpstops I lifted the vehicle on the hoist to do the exhaust which created a vacuum in all the air bags as I lifted the vehicle off the floor, realised this to late, I should have started the vehuicle and re-inflated everything before I lifted the vehicle up. A lesson learned.................:)

[Pete38]

What I do when there is no air in the bags is lower the car to around highway height on the corners with no air. Then start the car and choose high mode so the car lifts off the jack.

Can start at standard height to be extra safe but needs to be below high height to lift off

[PeterH]

I had the top of my left rear bag pop out of it's holder during inflation after doing some work on the eas recently, it made the same whoosh sound you describe.
I jacked up that corner of the body enough to allow access under the wheel arch, I could see the bag had indeed come away from its proper position, pulling the air line out as well, which casued the whoosh sound.
With the body still jacked up, I had to remove that circular weight attached to the diff to gain access, very easy, just two bolts from memory.
Then I was able to pull the top air bag pin and the air line out, ended up pulling the bag right out to check everything was ok. It's a bit tricky manouvering it out over the axle housing, but it will come out.
There was no damage to the air line or bag, so I replaced the o rings while I had it out, then put the bag back into position, reseating the top of the bag into its correct position with the air connection poking through the top of the mount. Then insert the pin and air line again, giving it a pull to make sure it is connected properly.
Then I dropped the jack, re inflated the system again, and it has been fine ever since.
Hope that is of some help!

[Nomad9]

Hi Pete38 and PeterH,
Interesting answers, Pete38 I am going to assume that the other three wheels are on the deck when you did your inflate. I am using a hoist which I suspect is compounding the problem, on the hoist the vehicle automatically goes to "super high mode" I'm assuming this is because the sensors read chassis high, suspension no load.

In answer to you PeterH, you describe a lot of similarities except possibly the last sentance. I haven't had any problem getting the bag in and out, getting pretty good at it now takes about a minute and a half. The circular weight you talk about is something I will have to investigate further, I don't seem to have one of these, the problem I have right now is taking priority over that bit.
My main issue is the air bag seems to crease in the middle, folds on itself and then goes over at such an angle that one of the ends pops off the mounting plate, this happens before the bottom section of the bag rolls over the mounting plate.

I have tried to fold the bottom mount into the bag, after a couple of beers and a lot of swearing I gave up. TV seemed a far better option at that point.

As mentioned earlier when I get home I'm going to put the bag back and leave all four wheels off the floor start the engine and wait until the compressor stops, or the bag comes off completely, a little bit of "***** or bust". The righthand side bag is fine with the wheel off the floor and folds perfectly over the bottom mount, I was on the verge of taking the R/H one off and changing that over to the left hand side, thought better of it after the second beer.

I'll report back how I go.

[PeterH]

Good luck with it Nomad9, hope you have better luck next try!
The circular weight I am talking about is called a mass dampener (from memory), it might only be on later model P38's, may not be on yours if it's an earlier model.
If you can get your bag out already then it's not an issue.
Just a thought, maybe it's the hoist that is causing your problems, I'd try putting the bag into position and then putting the wheels on the ground before inflation instead.
That's what worked for me at least.

[Pete38]

Hi Pete38 and PeterH,
Interesting answers, Pete38 I am going to assume that the other three wheels are on the deck when you did your inflate. I am using a hoist which I suspect is compounding the problem, on the hoist the vehicle automatically goes to "super high mode" I'm assuming this is because the sensors read chassis high, suspension no load.

In answer to you PeterH, you describe a lot of similarities except possibly the last sentance. I haven't had any problem getting the bag in and out, getting pretty good at it now takes about a minute and a half. The circular weight you talk about is something I will have to investigate further, I don't seem to have one of these, the problem I have right now is taking priority over that bit.
My main issue is the air bag seems to crease in the middle, folds on itself and then goes over at such an angle that one of the ends pops off the mounting plate, this happens before the bottom section of the bag rolls over the mounting plate.

I have tried to fold the bottom mount into the bag, after a couple of beers and a lot of swearing I gave up. TV seemed a far better option at that point.

As mentioned earlier when I get home I'm going to put the bag back and leave all four wheels off the floor start the engine and wait until the compressor stops, or the bag comes off completely, a little bit of "***** or bust". The righthand side bag is fine with the wheel off the floor and folds perfectly over the bottom mount, I was on the verge of taking the R/H one off and changing that over to the left hand side, thought better of it after the second beer.

I'll report back how I go.

Whenever I have my car lifted on a hoist I turn off the EAS with my isolation switch I fitted. Or before I had that leave a door open so no extended mode is triggered. I think with all thw wheels hung on the end of the shocks the system probably lets all the air out of the bags to lower it thinking all sensors are too high. Then you lower it down with no air and the bags get creases.

So if there is no air in any of your bags I can't see why lowering the car very slowly with the car running and all doors closed. Eventually it will get low enough to lift itself off the hoist. Don't lower it too quickly otherwise the system won't partially inflate/pump the bags up before the car hits the bump stops and folds the bags.

I also have the emergency air inflation so when my bags are emptied of air when the car isn't on the bump stops (jacked up and air let out of the system) I could manually pump air into the bags.

I have never had the car jacked up without the EAS turned off or bypassed so some of this is all thoughts, not experience.

[Nomad9]

Hi Pete38,
You make a very good point about the EAS and lifting the car off the floor, what you do is what I SHOULD have done, just had a moment, I was that keen to get my new exhaust on I just forgot.
With all four wheels off the floor the extended mode comes into play. I tried inflating the bag a little bit by opening and closing the raer passeger door and then lowering onto the floor the blasted thing still creased, I just don't think I put enough pressure in.

I believe at one point the bag was creased in half and sitting on top of the two halves, the ride hight sensor sensed that the vehicle wanted to go up, so introduced more air, at that point the seal broke and the bag popped off, then the rear of the vehicle came down, the R/H sensed things had gone down, so lowered, quite impressive to watch actually, that was after I had got over the shock of the bag popping off.

[davidsonsm]

Do you have a manual inflation kit? Could you try pressuring the bag manually whilst supervising its inflation? Ie watch it inflate to.see what's happening.

[Nomad9]

Hi there,
At this moment in time no I don't, however this is one option I have considered, this option is getting ever closer. I am hoping to have the vehicle on the hoist with the engine running and supervise the bag pressurising using the rear passenger door as the regulating method. Hoping of course the door doesn't actually shut which would then allow the bag to just grow and grow and grow........................being unable to reach the door handle.........:) Like the way you think.

[wayneg]

Get the car off the ramp and let the bags inflate. The one that wont, jack up the chassis to around std hight then with a second jack lift the offending corner enough to remove the wheel then airbag. Get the airbag rolled over the bottom pillar completely before refitting. If the bag is new this can be quite a task, Grease on the inside of the bag where it folds over will help. Refit the bag raising the jack to push the axle up. Refit wheel, lower to ground then lower the 2nd jack under the chassis just a little, try to keep the car about standard hight. Make sure the bag has still rolled over the pillar. Start the car and once pressure is in the bag remove the jack.
Object is to have the bag rolled over otherwise it will keep folding and breaking the seal

[Keithy P38]

What ^^^^ said!

Good replies lads!

[Nomad9]

Hi Wayne,
So you have basically hit the nail on the head. Thank you for the suggestion. What I might try is putting some washing up liquid around the bottom seal, mount the air bag back in place, leave the air line disconnected and then lift that side of the axel with my transmission hoist whilst I perform the "task" of getting the bottom seal to turn on the mount. Hold the axel in place with a ratchet strap, replace the air line and the wheel and drop to grade. Remove the ratchet strap and inflate. Could work. I spent a while on the task you mention last night without success, the bags are pretty new, and quite stiff.

[wayneg]

Its the inside of the bag you need to grease / lubricate.

[Nomad9]

Hi People,
So this is how it went, tried to get the bag over the bottom fitting, I tried everything, Wayne you weren't kidding that was a task. In the end gave up swathed in various lubricants and a very slippery air bag.

Come This morning, day off, revisited the problem, this is how I got the bag on and working properly.

1. Applied o-ring lubricant around the seal both on the bag and on the mount, top fitting.
2. refitted the bag on the car, two new silicon O-rings in the 6mm connection with a small amount of o-ring lubricant,
3. let the engine run for about ten minutes with the rear passenger door open.
4. dropped the vehicle to about normal ride height closed the door, let the bag inflate a bit until quite hard to the touch. Yes it is creased. Opened the door.
5. Now lifted the vehicle to close to max travel and or until I could straighten the creases out of the bag.
6.Magically the bag now formed over the bottom mount, it had nowhere else to go.
7. Now I dropped the vehicle very slowly watching the bag form over the bottom mount
8. As the vehicle dropped the pressure increased in the bag so forming over the bottom mount.
9. Closed the door and everything happened like it should, vehicle levelled off after another five minutes the compressor stopped.

I'll now have to see what it looks like tomorrow when I take said vehicle to work.

Thank you everybody for the suggestions and the help.

[mtb_gary]

Well done Nomad9. :clap2:

Gary

[wayneg]

Well done
I have done the bag roll over a couple of times recently so know how hard it is.
I keep the outside of the bag clean and dry and only lubricate the inside which seems to be the binding point. Leaning over the bag, both hands pushing down I can get it to roll over, once started it goes on quite easy.