W220 - Noisy Suspension Pump

FrostyDon

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Hey all, I've been trawling this forum for a couple of weeks and it was a great help in saving me a fortune fixing my heater blower last weekend, instead of paying £400.00 to have a new one fitted I simply removed it, unseized the motor, lubed the bearings, tested it on my car battery then replaced it working!
(Water had got into it from the plenum chamber drain being blocked).

Anyway, I have another problem which I think is a little more serious.
A couple of weeks ago I arrived at home, turned off the engine,got out of the car and was met with a loud rattling pump kind of noise from around the front o/s wheel area, bearing in mind that this was with the engine turned off and the key in my hand!
I tried to starting the engine but it made some pretty loud clunking noises as if the engine was under a big load, the only solution I could find to stop this pump noise was to disconnect the battery.
So I spent all night worrying about how many thousands of pounds this was going to cost me.

The next morning I reconnected the battery (after having to almost break into the boot!), no pump noise, when I turned the ignition 2 clicks there was an "Airmatic - Visit workshop" error on the dash, so I started the engine without a hitch, the suspension seemed OK, I pressed the "raise vehicle" button on the dash and sure enough the engine seemed to raise OK and the "Airmatic - Visit workshop" had gone so I thought my problems were over!
I took it for a quick drive and when I got to about 20mph I could hear that loud rattly pump noise again, it went on for about 20 seconds then the sound of a pressure release valve and the pump stopped, after a few seconds it starts again and this cycle seems to continue, except when the car is stood still or moving very slowly, then it doesn't happen.

After reading through this forum and finding several people having similar issues I decided last weekend to change the Airmatic relay, which I did, but it appears to have made no difference.

I do notice that the front o/s suspension doesn't seem to drop or raise like the other corners but other than this the only "problem" I have right now is that the pump seems to be running quite a lot and is very noisy.

I've been quoted about £380.00 for a new pump to be fitted by an Indy in Doncaster but I'm not totally convinced that this will fix the problem.

Any ideas guys?
Any help greatly appreciated.
 

47p2

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The end of the pump will have came away from the main body, I repaired mine with some pop rivets and it lasted a few years until I decided that my pump was getting weak and changed it last summer.

The pump is in the o/s front wheel arch behind the bumper. It's easier to remove the wheel and drop the liner down to allow access
 
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FrostyDon

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John,
Thanks for the reply.
I had read one of your previous posts where u talked about this and it does make sense.
However, does this explain why it only seems to happen above approx 20mph and why the suspension does lift when the car is first started (except front o/s which never seems to change)?
This has been happening for about 2 weeks now and I do almost 100 miles a day in her, is there a danger the pump could burn out as it seems to be running a lot of the time?
 

47p2

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Make sure the relay you changed is the updated one, it should be part number A002 542 72 19 .

Attached is a picture of the end plate that comes loose, you need to drill out the old rivets and re-rivet it

The pump as it is will be hanging on for grim life, because the end plate is off it won't be working as efficiently as it should and will be running more or less all the time which will cause all sorts of problems. The compressor is not expensive compared to other MB compressors, around £250 for a new one and that includes the the new pipe and relay, so if yours does burn out it's not the end of the world. Just looking I see your car is a 2000 model, possibly on the original compressor, so it might be time to change it before it packs up completely, it's not a big job and well within the scope of the average DIY'er.

Best have it checked as soon as possible, I'm not sure if the car has to be plugged into STAR to clear any faults once a new pump is fitted, I changed mine last summer before any faults were reported as I hate the thought of paying for unnecessary software faults
 

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FrostyDon

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John,
Really appreciate all the help, I will print out what you have said and take it with me tomorrow when I take the car in.
Hopefully the guy at the indy will be able to follow these instructions.

I would attempt it myself but I'd heard some stories about "Imploding Spheres" and things when the pump is removed without the wheels off the ground.

I'll post the outcome in a couple of days.

Thanks
 
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