I did some searching, couldn't find specific to my problem, so here goes

suspension on all four's and red warning message on dash, I am pretty sure that this is not because of a leak, but because the compressor is not topping up the system and over time while driving the air is released as it happens very slowly, but if the car is left it will stay in whatever position it was left in.

What I know

I changed the compressor for a new one

I changed the relay for the new Hella relay

With a test lamp there is no power at the big orange fuse (second from front of fusebox) which I believe is the airmatic fuse (tested both sides of fuseholder)

When I remove the relay in position "O", and short out pins 30 and 87 (in effect closing the relay and completing the circuit) the pump comes on and starts pumping up the suspension.

with relay in and a wire (+12v via fuse) stuck into pin 86 to energize the relay nothing happens (relay does not click) pump does not turn on.

So my questions

1, When I put the test lamp on the big orange fuse should it light up, or does power only go to it when the airmatic system tells it to i.e. when it needs the compressor to turn on to add air to the system

2, If I can short out pins 30 and 87 to start the pump, does this power originate from the big orange fuse, and if so why does my test lamp not light up when testing the orange fuse and the compressor is running with the short out ?, or is the orange fuse for some other part of the airmatic system.

3, what are the cables for at the airmatic pump .. there is one plug with 2 thick cables ( a brown one and a red one), and there is another plug with 2 thin wires (a green one and a grey/red one), what do these wires do for the pump, and does anybody know where they come from (i.e. fuse, relay etc) I know the thick brown wire is earth, and I am assuming the thick red wire is a +ve, if so is it a switched positive or a permanent positive

4, are there any more fuses and relays (other than whats explained above) that have anything to do with the airmatic system.

Thanks for your help

Cheers
Kev

 

Did u check for power at the fuse when u bridge the relay. Most likely it's fused after the relay. Connect star and actuate relay. Term 85 or 86 should have ign power via another fuse I guess. Airmatic most likely supplies ground to relay. I can look in the diagram if u like to see exactly how it's wired. Good luck

 

Hi Russell,

Thanks for getting back so quick, Didn't think to check power at fuse when relay is bridged, will check it out in the morning,

I would appreciate if you could look in the wiring to see how the relay is energized, ground or positive trigger, and also which pins at the relay do what. And also how the power gets down to the compressor from the relay if thats possible.

many thanks

Kev

 

Checked the orange fuse and power is going to it when I bridge the contacts and get the pump working,

But another strange thing, when the pump is working (bridging the contacts), the car still does not rise, I cant hear any hissing noises or leaks (its a new compressor), I know some air is getting into the front suspension because there is a very small crack which lets out micro bubbles (I will araldite it up when I have sorted everything else out), but there doesn't seem to be enough enough air pumping in to raise the suspension.

Could whatever is stopping the relay from energizing (I am assuming electrical fault or broken/burnt out cable) also be stopping the air from getting to the suspension struts, maybe something that controls the air valves, but if so why would some air be getting to the struts.

By the way its only the front struts that are down, the back are still raised

 

The car won't raise if u bypass the relay. The valve block is not being actuated.
To do tests on airmatic use star and use actuations or follow the tests. U cannot diagnose further without the proper equipment

 

Thanks Russell,

Think I may give up and sell it for spares or repairs, apart from the suspension its a good car, but I dont want to be spending any more cash on it,

Got a Triumph Stag on my mind, they have their problems, but at least I wont need a computer to fix them haha .. just an ear ..

 

Found this video that should help me open up the valves to get enough air into the front struts so I can at least move the car, Mercedes wanted £141 + VAT to put it on their star system .. found a non main dealer Mercedes specialist who will do it for £45, so I may give it one last go, maybe the control unit needs resetting and codes cleared before it will send signals to the airmatic system.

 

Some good news,

I have put the airmatic system back together again, and I started the car and all four struts raised to the correct ride hight.

I took it out for a 10 minute spin, and after about 5 minutes I got the red dash warning to stop the car suspension low,

I got the car home and it was low on the right side front (drivers side front in the UK), all other struts looked to be the correct height.

I stopped the car, waited for a bit and then started it again, and the pump kicked in and raised the front right to the correct height, Turned the car off and it been at the correct height for the last couple of hours.

I know I don't have leaks, so what is the most likely cause for the one strut to deflate, could it be a strut or ride height sensor thats faulty ?

If this is the most likely cause and I replace it, does it then need star to set it up, or can I just fit and forget.

Cheers
Kev

 

It needs either a strut , valve block or height sensor . My vote is valve block

 

If the ride height sensor is malfunctioning so that it isn't telling the system to raise the corner to the right height, the computer wouldn't know that the corner was low, and wouldn't set the warning message.

A leaking strut would probably leak while parked. Note the "probably" in there.

Valve block would be my first guess.

 

Thanks guys,

A little bit more info,

I had to take the car to have the MOT done on it, and it failed on the drivers front strut because of this reason "Air suspension fouled by moving parts", I had a look under the car when it was on the ramp and the strut has somehow slightly twisted so that the damper is rubbing against the control arm (I think its the control arm).

I am guessing that if the strut is twisted it would interfere with the operation of the ride height sensor and perhaps making it give out the wrong information ?

When I tested it when it was all pumped up, I drove it quite aggressively and the drivers side went down and I had the warning. But if I drive it gentle everything seems ok.

I did remove the valve assembly (as in the video in the above post) and tested each valve and they all opened and closed ok and let the air through when opened and stopped the air when closed. So I am pretty sure its not that.

Thoughts with this new information ?

 

Well you've described several problems with the strut , so as before it's still either the strut , valve block or Height sensor . But since you've described so many problems with the strut it might be the strut

 

Well the only problem with the strut is that it has twisted in the bottom mount, there doesn't seem to be anything else obviously wrong with the strut, and the twisting of the strut I suspect may be effecting the way in which the ride height sensor is operating as that's connected to both the strut and the chassis, so any twisting could potentially throw out the calibration., that would be my educated guess as I have tested the valves as I said before and they are working fine, and there is no air leak in the strut (tested with bubble spray) except a very minute pinhole that has now been repaired

So at the moment I think I will do some straighten the strut in its mount and replace the sensor and see what happens.

 

Spray soapy water on strut bellows check for leaks.

 

I think that the ride height sensor is attached to the upper control arm, not the strut. I see no way that twisting of the strut could affect the ride height sensor, unless the wire harness is rubbing.

The strut is basically round, and the mounts on both ends are located on the center line of the strut, so I don't see how twisting the strut could make the strut itself foul the control arm. Perhaps the wire harness is touching the arm?

There is no practical way to test the strut operating seal for leaks. The seal is a fabric and rubber ring that is attached to the inner and the outer tubes of the strut, and rolls up and down the strut with movement. You can't see or access the seal. It is possible to have a leak in a portion of the seal that usually sits against one of the tubes so that the contact blocks the leakage. If the seal rolls up or down to expose the leaking area, you could get a leak - perhaps during your sporting driving. Then when the seal returns to its normal ride position, the leak is blocked off.

One of the most common problems after strut work is that the two wire connectors are not properly plugged into the receptacles at the front of the wheel well.

 

Thanks for replies guys,

Have been driving the car now couple days and all is working as it should, I will double check the cable connections, still not 100% confident with it yet but I will see how it goes.

done the soapy water test, there was a pinhole crack but I repaired it with epoxy and no leaks at the top of the struts now.

Will start driving it more aggressive over the next few days and see what happens, maybe the first time it happened it may have just been settling down

 

If the cable connections are bad, the car may be lifted slightly, and/or may ride a little roughly. Failure mode is lifted if the ride height sensor connection is bad; full firm if the strut connection is bad.

 

Did u spray the bellows itself not just the top

 

Didnt do the bellows, the wheels are coming off on Sunday for disk and pad change, and also straightening of the strut, so will spray them when I do that.

 

If it's not leaking now I wouldn't touch the strut or do any straightening

The leak was probably cured by the epoxy

Leave things alone if they are working now

 

I have to twist the strut because they failed it on the MOT because the damper was rubbing against the control arm, cant drive it on a public road till it passes the MOT, so no option there

 

We spoiled Americans often don't realize that UK owners, German owners and others live in a much more rigid regulatory environment than we do.

Until it becomes a museum piece, every UK road vehicle must periodically pass an unbelievably thorough and strict inspection - the MOT (Ministry of Transport). No pass, no drive. Thousands of vehicles fail the test annually - perhaps for excessive chassis rust, for example, or for anything that the inspector thinks will make the vehicle less safe.

In Germany, you cannot put anything of any consequence on your vehicle that has not been inspected/tested and approved for your make and model. As an example, every aftermarket light design is approved for specific vehicles - and only those vehicles. Same thing with aftermarket wheels. And having a wheel approved for an E-Class does not mean that you can use it on an S-Class. I believe that Germany also has a strict periodic inspection. They make Kalifornia look normal.

I'm sure that one of our overseas members will correct me if I have misunderstood the situation...

 

Wally, you are pretty much correct, although in the UK we are not as strict as in Germany. The bloated European Union with its pathetic leaders and out of touch regulations is a laughing stock, they make regulations up just to justify their existence.

The European Union were trying to being some pathetic regulations in that would basically have rendered ALL classic cars useless as they would not have passed those regulations, and would not have been allowed on the road. But in the UK I think the Government rejected those regulations (think we have a veto)

But still they bring more in every year.

If I could live in the States .. I would.

 

We have many, many vehicle laws that simply aren't enforced in many states, or are only enforced when the LEO needs a probable cause to stop someone. Worn, mis-matched tires? Not a problem. Brake light out? Not a problem. No brakes on the rear? Not a problem. Oil smoke rolling out the tailpipe? Problem in a few states, but not in most.

A few states have a tight inspection program, but fewer states are now willing to pay the cost.

 

Come to South Africa. No emission tests. One roadworthy certificate at change of ownership. Any modifications u like. I have seen R170 slk's with R171 slk front end fitted.