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Secondary Air Pump Motor Replacement
 
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Pelican Technical Article:

Secondary Air Pump Motor Replacement

Kerry Jonsson

Time:

1 hour1 hr

Tab:

$300

Talent:

**

Tools:

T10 Torx socket with ratchet or wrench

Applicable Models:

Mercedes-Benz W211 (2003-09)

Parts Required:

Secondary air pump motor

Hot Tip:

Work on a cold engine so the mounting brackets are not hot to the touch

Performance Gain:

Eliminate P041X and P141X codes

Complementary Modification:

Clean out secondary air passages

Government regulations require that fuel economy ratings increase as the years pass and harmful emissions are reduced. During the combustion process raw fuel (Hydro Carbons. aka HC) are mixed with incoming air at a specific ratio for complete combustion. As the air/fuel mixture goes through the combustion process we should realize the process is less than 100 percent efficient. The spent exhaust gases still contain HC and oxygen but in smaller amounts. Other harmful emissions are carbon dioxide, carbon monoxide, oxides of nitrogen and water (H20) in the form of vapor. Carbon dioxide, oxygen and water vapor are not immediately harmful gases but carbon dioxide does contribute to greenhouse gases. Gases that are harmful to the human body are HC, carbon monoxide and oxides of nitrogen. Carbon monoxide is the most deadly of gases as it is colorless and odorless and can starve human lungs of oxygen leading to death. This is why it is recommended you do not run your engine in a confined space like a garage for very long.

The perfect mixture an engine should run at is 14.7 parts air to one part fuel. This allows the catalytic converter to operate at the greatest efficiency to continue to clean up harmful emissions. When an engine is in the warm up phase the mixture needs to be richer, meaning it needs more fuel to air such as an 8 or 10 to 1 ratio. This way the car will not stumble, hesitate and stall. To get the catalytic converters up to temperature right away manufacturers installed secondary air pumps to pump fresh, oxygen rich, air into the exhaust. This fresh air would continue the combustion process in the exhaust manifold and quickly heat up the catalytic converter. Once the catalytic converter is heated up the engine management computer can run the car at a 14.7:1 air/fuel ratio. The secondary air pump makes this possible. Mercedes Benz uses an electric secondary air pump mounted in front of the intake manifold. This way the heat from the engine evaporates any moisture that has built up in the secondary air pump. Being that there is moisture in the air any time you compress the air in a pump, condensation will result and create corrosion in the components of the system. This pump should run when the engine is fully cooled off and started. In about 1 to 2 minutes the pump will start to run and run for about 1 to 2 minutes. If this pump were to fail the catalytic converters would take longer to heat up. The engine management computer can detect the secondary air pump is not working and set a code in the P041X and P141X ranges. In this tech article we will show you how to replace your secondary air pump motor.

Because the secondary air pump is attached to the engine it can get quite hot if the engine is fully warmed up. When changing the secondary air pump motor be sure the components are cool to the touch before attempting repairs.

This picture illustrates the front of the engine compartment.
Figure 1

This picture illustrates the front of the engine compartment. Locate the secondary air pump (green arrow).

Using a T10 Torx socket and ratchet loosen and remove the mounting bracket fastener.
Figure 2

Using a T10 Torx socket and ratchet loosen and remove the mounting bracket fastener. Note the ground wire (green arrow) for the secondary air pump is also attached to this mounting bracket fastener, so donÂ't forget to reattach it during installation. This is the one fastener for the pump. Once the remaining items are disconnected (in the following steps) the mounting bracket is opened to allow the pump to be removed.

On the left side of the secondary air pump, unplug the electrical connector by squeezing the two locking tabs on each side and pulling it in the direction of the blue arrow.
Figure 3

On the left side of the secondary air pump, unplug the electrical connector by squeezing the two locking tabs on each side and pulling it in the direction of the blue arrow.

Locate the secondary air pump supply hose (red arrow).
Figure 4

Locate the secondary air pump supply hose (red arrow).

Remove the hose from the secondary air pump outlet port by pulling it straight up.
Figure 5

Remove the hose from the secondary air pump outlet port by pulling it straight up.

Move the top of the mounting bracket toward the front of the engine compartment.
Figure 6

Move the top of the mounting bracket toward the front of the engine compartment. Lift the secondary air pump up until you unhinge the lower mounting tabs (red arrows) from the engine block. This photo shows looking under the air pump, past the thermostat housing. You do not have to remove the upper radiator hose to perform this step but I have done so for photographic purposes.

Lift the secondary air pump out of the engine compartment.
Figure 7

Lift the secondary air pump out of the engine compartment. Installation is the reverse of the removal steps. Remove the secondary air pump mounting bracket from the old secondary air pump and install it on the new one. Fit the bottom of the secondary air pump mounting bracket two tabs in the two slots on the block and push downward. Lever the upper part of the secondary air pump mounting bracket towards the back of the engine compartment, install the ground wire on the fastener and install the fastener then tighten it. Fit the secondary air supply hose to the secondary air pump output port. Start the engine when it is cold and verify the pump runs for 1 to 2 minutes after a couple of minutes of the engine running.

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Comments and Suggestions:
Dwight B Comments: Where can I order the secondary air injection system for my 2004 MBenz E320 6cyl used but original for my Benz pls.
July 4, 2016
  Followup from the Pelican Staff: Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
stanley Comments: Hi, I am looking for an new secondary air pump for my 2006 Mercedes E350 WDB211 model. Will the American made air pump be suitable for Australian car ? Please also provide me with total price, including transport cost etc.
September 2, 2015
  Followup from the Pelican Staff: I’m not the best with part numbers.

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 

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