My son took our 08 GL550 to school this a.m. It wouldn't start after school because of a dead battery. After replacing the battery, the car starts again, but the airmatic pump is running non-stop key on or off which is what must have killed the battery.. Ride height seems normal and I don't hear any leaks once I pulled the pump fuse but the malfunction warning came on.

I have 165K miles, and while all 4 corners have been replaced with Arnotts (in the last 30K miles), I think the pump is still original. Before ordering a pump from Arnott, could something else be wrong, or is this just a bad pump? Thanks for any help. This thing has a real talent for breaking on the Friday of 3 day weekends.

Replace the relay

It turned out both were bad. The relay was causing the pump to run non-stop, but the pump had a leak so I replaced that as well. The relay from the dealer was a little different in appearance than the original and was made by Hella. For anybody replacing it in the future, it is the third one from the left as you're facing the car in the fusebox in front of the shock tower.

Before ordering the pump from Arnott, I called the dealer and they had one in stock for $520 ($40 more than Arnott). I would have rather used the Arnott since theirs is a lifetime warranty new unit instead of a reman (which I assume what the dealer was selling since they wanted a core), but putting the car back into service today was far preferable to next week. The parts guy said they always replace the fuse and relay along with the pump.

The pump was pretty easy to R&R. Just take out the fenderliner in the front of the RF wheel, and it is easy to access right behind the bumper.

oem amk brand new pump can be had for $350. check ebay.

I used partsgeek.com and they sent an Arnott for 250$

I saw the ebay units, but didn't know about the partsgeek option. I might have waited a few days for that big of a price difference. Hopefully I'm done with air suspension replacements for awhile.

Next up the cam magnet behind the power steering reservoir.

Do you have a link to it? It only shows me $400+ options.

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2010 Mercedes GL350 Air Compressor - 949-911 Dorman - $212.33
Qty Ordered: 1, Qty Shipped: 1


Disclaimer- It doesn't actually say Arnott, but this was a brand new unit. No core needed to be returned. My guess is that Arnott repackages this item.

The Dorman looks identical to the Arnott. It's been super quiet, and has same case stamp numbers as Arnott.

Thank you. But do you have a link on their website to this air compressor?

Order from Partsgeek at your own risk.

https://grassrootsmotorsports.com/fo...k/80253/page1/

I've ordered parts from them for various vehicles. Always positive experience.