ABC Pump noise?
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Newbie
Joined: Jan 2013
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From: LR, AR
2007 S550
ABC Pump noise?
I've recently developed a low pitched "growling" noise in my '07 S550 which just turned over 50K mileage. It's not throwing any codes but is definitely a sick puppy. I was of course worried about the balance shaft gear issue but my mechanic says no worries there! My Indy checked belts, motor mounts, tranny mount which all seem OK, he now thinks it's the ABC pump going bad. I do have an aftermarket warranty which will cover 50% of the cost, but I'm still looking at a substantial bill. I'm just wondering if any of you have any experience such as this and was replacement of the ABC pump the solution to the problem? Any input would be appreciated! 
Thread Starter
Newbie
Joined: Jan 2013
Posts: 14
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From: LR, AR
2007 S550
Thanks ImInPa... The noise just began suddenly last week and is present at idle and grows progressively with RPMs. It does seem to level off at highway speed, (or maybe it just blends into a constant level with road noise). No codes are present, no warning lights are on & the car seems to drive fine. But it's definitely an UN-characteristic low pitched growl/humm, (LoL - think of Boris Karloff as Frankenstein... that's the closest description I can give you of the sound it's making!) I've been reading some posts on the forum and now suspect it may be the damper/dampening unit that sits on top of the pump and not the pump itself. Going to run this by my Indy to get has thoughts before sinking $$$ into the new ABC pump. Your thoughts, ideas, suggestions are welcomed!
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Joined: Jan 2011
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From: Central Pennsylvania
2012 S350 Bluetec 4Matic, Diamond White, P2
It does not sound like it would be the ABC pump based on your description. I do not believe it would continue to increase as the vehicle speed increases. I really have no idea. I hope your Indy nails it.
Thread Starter
Newbie
Joined: Jan 2013
Posts: 14
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From: LR, AR
2007 S550
Hey ImInPA... Just a quick follow-up to my ABC Pump issue. After trying a couple of other things, (replaced motor & tranny mounts), my indy and I arrived at the same conclusion, (I was researching the issue on this forum & he was looking at service bulletins), long story short we both found info pointing to shock absorber damper/dampening unit that sits on top of the pump. Well $450 later we discovered that this was the culprit! Sure beats the heck out of an $1800 ABC Pump, (although I was dissappointed that my ASC warranty didn't cover it). So that's my experience... hope this info can help someone else save a few bucks & avoid an expensive & unnessasery repair!
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MBWorld Fanatic!
Joined: Jan 2011
Posts: 1,747
Likes: 20
From: Central Pennsylvania
2012 S350 Bluetec 4Matic, Diamond White, P2
Glad to hear it was not the pump. I really do miss a good, well engineered, mechanical suspension. But, there is no such option available here in the US.
