Noise from some kind of a vacuum pump?

2007 MERCEDES BENZ S600
101,000 MILES • V12 • TURBO • 2WD • AUTOMATIC
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BHAMDOC1973
  • MEMBER
  • 2,007 POSTS
I listened to it using a screwdriver and it is coming from this thing. Do you know what this is? Looks like there are two of them side by side. Sounds like power steering but the pump is on the other side of the engine. If i remove the belt to see will the check valve pump still work? Trying to see if i can eliminate.
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Aug 6, 2022 at 1:42 AM
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JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,246 POSTS
Hi,

That sounds like the secondary air pump. It should turn off and on. Does it run all the time?

If you look below, I attached a pic and circled a few things. Do you recognize any of the items in the pic?

Item

M33 is an electric air pump.

Y32 is the air pump switch-over valve

126 shows the two-air injection shut-off valves. Those are the two things I suspect you are seeing.

If you look at the last two pics, they are of the under-hood fuse/relay box. In the last pic, I indicated the air pump relay. Remove that and see if the sound stops.

Let me know what you find or if you have other questions.

Take care,

Joe

See pics below.
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Aug 6, 2022 at 1:57 PM
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