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Replacing Your Mercedes Air Pump
 
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Pelican Technical Article:

Replacing Your Mercedes Air Pump

Steve Vernon

Time:

1 hour1 hr

Tab:

$450

Talent:

**

Tools:

E10 Torx driver

Applicable Models:

Mercedes-Benz W203 (2001-07)

Parts Required:

New air pump

Hot Tip:

Use care working on old rubber hoses

Performance Gain:

Pass a smog test

Complementary Modification:

Air pump check valves

If your car is not passing a smog test one of the things that could be wrong is the air pump. This article will show you how to replace the air pump on a Mercedes-Benz W203.

Begin by disconnecting the ground from the battery and making sure it can not accidentally make contact again while you are working.

You will need to remove the two air inlet ducts as well as the front engine cover to get access to the air filter housing on top of the engine.

Remove each duct by compressing them towards the engine and slipping them off the air inlet.

With the ducts off remove the front engine cover. It pulls up and away from the engine. The cover is held on by five clips and will easily come off with hand pressure.

Next you will need to remove the main engine cover that also houses the air filters. It is held on by four pressure clips. You can see the two at the front of the engine, to remove the housing lift it at the front of the engine and once the front clips release the rears (which you can not see) will release as well.

Now you have access to the air pump. The pump sits right at the front of the engine above the coolant pump and between the two air pump check valves.

There is a hose that runs between the two check valves that connects to the air pump. Carefully remove the hose from the pump by slipping it up and off the pump, there is no clamp. This hose can get hard and brittle over the years and may crack. It might be a good idea to order and extra hose if yours looks old before you begin the job so you will not be stranded if it breaks.

Remove the electrical connector to the pump. Not that there are two ground wires attached to the E10 bolt that holds the pump in place. Use a socket and remove the E10 bolt.

With the bolt removed the mount hinges down and out from the top of the pump. Remove the old pump.

Installation is the reverse of removal.

Begin by disconnecting the ground from the battery and making sure it can not accidentally make contact again while you are working.
Figure 1

Begin by disconnecting the ground from the battery and making sure it can not accidentally make contact again while you are working.

You will need to remove the two air inlet ducts (red arrows) as well as the front engine cover (yellow arrow) to get access to the air filter housing on top of the engine.
Figure 2

You will need to remove the two air inlet ducts (red arrows) as well as the front engine cover (yellow arrow) to get access to the air filter housing on top of the engine.

Remove each duct by compressing them towards the engine (red arrow) and slipping them off the air inlet.
Figure 3

Remove each duct by compressing them towards the engine (red arrow) and slipping them off the air inlet.

With the ducts off remove the front engine cover.
Figure 4

With the ducts off remove the front engine cover. It pulls up and away from the engine (yellow arrow).

The cover is held on by five clips (red arrows) and will easily come off with hand pressure.
Figure 5

The cover is held on by five clips (red arrows) and will easily come off with hand pressure.

Next you will need to remove the main engine cover that also houses the air filters.
Figure 6

Next you will need to remove the main engine cover that also houses the air filters. It is held on by four pressure clips. You can see the two at the front of the engine (red arrows).

To remove the housing lift it at the front of the engine and once the front clips release the rears (which you can not see) will release as well (red arrows).
Figure 7

To remove the housing lift it at the front of the engine and once the front clips release the rears (which you can not see) will release as well (red arrows).

Now you have access to the air pump (red arrow).
Figure 8

Now you have access to the air pump (red arrow). The pump sits right at the front of the engine above the coolant pump and between the two air pump check valves (yellow arrows).

There is a hose that runs between the two check valves that connects to the air pump (red arrow).
Figure 9

There is a hose that runs between the two check valves that connects to the air pump (red arrow). Carefully remove the hose from the pump by slipping it up and off, there is no clamp. This hose can get hard and brittle over the years and may crack. It might be a good idea to order and extra hose if yours looks old before you begin the job so you will not be stranded if it breaks.

Remove the electrical connector to the pump (red arrow).
Figure 10

Remove the electrical connector to the pump (red arrow). Note that there are two ground wires (yellow arrow) attached to the E10 bolt that holds the pump in place.

Use a socket and remove the E10 bolt.
Figure 11

Use a socket and remove the E10 bolt.

With the bolt removed the mount hinges (red arrow) down and out from the top of the pump.
Figure 12

With the bolt removed the mount hinges (red arrow) down and out from the top of the pump. Remove the old pump.

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Comments and Suggestions:
soulman Comments: Hi guys, I drive a w203 c180 2000 model, do these have a relay and a fuse like the later models, for the secondary air pump? If not how does the air pump switches on. Many thanks.
November 22, 2014
  Followup from the Pelican Staff: I would think. However I do not have that model in the US, so I have no wiring diagram available to me to check. - Nick at Pelican Parts  
soulman Comments: Hi there, I drive a w203 2000 model, 111M engine C180.just below the alternator there is what seems to me like an air pump. I read in some threats that these models do not have a SAI pump. if so what unit is this then & when does it come on & what powers it up. Thanking you in anticipation.
October 9, 2014
  Followup from the Pelican Staff: Below the alternator, could it be the A/C compressor? Can you share a photo of it? - Nick at Pelican Parts  

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