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#1
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On a M104 3.2L what is the last pump on the left...?
It is the last pump on the serpentine belt - farthest on the passenger side. This pump is making 'hollow', kind of 'whirring' noise especially when cold. What is it? How much does one cost? Is it the air pump?
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dtf 1994 E320 Wagon (Died @ 308,669 miles) 1995 E300 Diesel (228,000) 1999 E300 Turbodiesel ( died @ 255,000) 2006 Toyota Tundra SR5 AC 4X4 (115,000 miles) rusted frame - sold to chop shop 2011 Audi A4 Avant (165,000 miles) Seized engine - donated to Salvation Army BMW 330 xi 6 speed manual (175,034 miles) 2014 E350 4Matic Wagon 128,000 miles 2018 Dodge Ram 21,000 miles |
#2
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Assuming "left" staring at the engine...you would be looking at the air pump.
It's only doing it's job in the first few minutes after startup, pumping air into the system to hasten cat warmup so that optimum emissions efficiency can occur quickly. In Europe, the sniffer gets inserted and data analyzed within the first 60 seconds of startup...a far more stringent test than in the US. In fact, it probably isn't needed for US emissions, except that the missing component would fail the visual portion of the inspection. When the air pump get old, the most common failure is that the clutch bearings wear out and seize. I believe kits are now available to replace just that, rather than the whole $800+ unit. The bearing are a weird size and can't be procured easily.
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2009 ML350 (106K) - Family vehicle 2001 CLK430 Cabriolet (80K) - Wife's car 2005 BMW 645CI (138K) - My daily driver 2016 Mustang (32K) - Daughter's car |
#3
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Thanks. Great explanation. I called the dealer and asked about the air pump cost and was shocked at the price. Looks like I'll need one in the near future. I also have a code 26 fault which is the 2-3 upshift delay to warm up the cat. I am assuming thatthis fault is not related to this failure?
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dtf 1994 E320 Wagon (Died @ 308,669 miles) 1995 E300 Diesel (228,000) 1999 E300 Turbodiesel ( died @ 255,000) 2006 Toyota Tundra SR5 AC 4X4 (115,000 miles) rusted frame - sold to chop shop 2011 Audi A4 Avant (165,000 miles) Seized engine - donated to Salvation Army BMW 330 xi 6 speed manual (175,034 miles) 2014 E350 4Matic Wagon 128,000 miles 2018 Dodge Ram 21,000 miles |
#4
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That "hollow, whirring" noise is not indicative of a failure (mine does that too)...a screeching noise IS!
And the air pump has nothing to do with the upshift delay...as I stated earlier, it does its job pretty early upon startup, then ceases.
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2009 ML350 (106K) - Family vehicle 2001 CLK430 Cabriolet (80K) - Wife's car 2005 BMW 645CI (138K) - My daily driver 2016 Mustang (32K) - Daughter's car |
#5
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You can get just the pulley kit for your air pump 104-140-08-86,pump usually OK.pulley bearing is cause problem.
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MB STARS Master Guild Technician,17 years MB tech 14 years independent shop owner |
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