How to Replace an Air Injection Pump Belt

The air injection system introduces oxygen into the exhaust to reduce emissions. The heart of the air injection system is the air pump, or smog pump.

Most modern air pumps are electric, but older ones are belt-driven. The belt can be either a v-belt or serpentine belt design. Over time, the air pump belt may wear out or show signs of malfunction. Here is a guide on what to do when it's time to replace it.

Part 1 of 5: Prepare to replace the air injection pump belt

Materials Needed

How to Replace an Air Injection Pump Belt 2

Step 1: Locate the belt routing diagram. Before you remove the old belt, locate the belt routing diagram. This will help you install the new belt correctly.

Most of the time, the belt routing diagram can be found inside the engine compartment. If it is not, consult the repair manual for your vehicle for it.

Part 2 of 5: Remove the serpentine belt if equipped

How to Replace an Air Injection Pump Belt 3

Step 1: Move the tensioner. Use a ratchet or dedicated serpentine belt tool to push or pull the tensioner away from the belt.

How to Replace an Air Injection Pump Belt 4

  • Note: Some tensioners have a slot for inserting a ⅜” ratchet head end into while others have a traditional bolt head.

How to Replace an Air Injection Pump Belt 5

Step 2: Remove the belt. While still holding the tensioner in place, slide the belt off the pulleys.

Part 3 of 5: Install the serpentine belt

How to Replace an Air Injection Pump Belt 6

Step 1: Consult the belt routing diagram. Consult the belt routing diagram and ensure that you know how to install the belt correctly.

How to Replace an Air Injection Pump Belt 7

Step 2: Move the tensioner. Push or pull on the tensioner so that the new belt can be positioned on the pulleys.

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Step 3: Install the belt. Slide the new belt onto the pulleys and let go of the tensioner.

Double check the belt diagram to ensure that your new belt is routed correctly.

Part 4 of 5: Remove the v-belt if equipped

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Step 1: Loosen the mounting bolts. Loosen the pump mounting bolts and/or adjustment bracket bolts but do not remove them.

How to Replace an Air Injection Pump Belt 10

Step 2: Move the pump. Move the pump inward until the belt can be removed.

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Step 3: Remove the belt. Slide the belt off the pulleys.

Part 5 of 5: Install the v-belt

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Step 1: Install the new belt. Consult the belt routing diagram to ensure that you know how to install the belt. Install the belt over the pulleys.

How to Replace an Air Injection Pump Belt 13

Step 2: Put the pump back. Move the pump back into place. The belt should have about ½” of deflection if the belt is properly tensioned.

How to Replace an Air Injection Pump Belt 14

Step 3: Tighten the pump mounting bolts. Tighten the pump mounting bolts and/or adjustment bolts down until they are snug.

Double check the belt routing diagram to verify that the belt is routed correctly.

You should now have a nice new air pump belt installed. If this seems like something you’d prefer to leave to the professionals, YourMechanic offers an expert air pump belt replacement service.


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Recent Serpentine/Drive Belt Replacement reviews

Excellent Rating

(5,264)

Rating Summary
5,038
126
27
19
54
5,038
126
27
19
54

Andrew

11 years of experience
841 reviews
Andrew
11 years of experience
Chevrolet Equinox L4-2.4L - Serpentine/Drive Belt - Grandview, Missouri
When he arrived he found that there was another issue that ended up being a much cheaper fix for us, when he could have said both issues needed fixed and we would have never known. He did find another problem that will need addressed eventually and because of his honesty we will use him again to fix that one also.
Mercury Milan - Serpentine/Drive Belt - Shawnee Mission, Kansas
Very friendly and explained what he was doing and showed me the badly frayed belt that was causing the problems

Theodore

16 years of experience
1587 reviews
Theodore
16 years of experience
Nissan 200SX L4-1.6L - Serpentine/Drive Belt Replacement - Issaquah, Washington
Super professional. Straight to the point, completed the job in less than a hour. No complaints. Good mechanic.

Attila

19 years of experience
906 reviews
Attila
19 years of experience
Infiniti G37 V6-3.7L - Serpentine/Drive Belt - Basking Ridge, New Jersey
He was faced with a difficult situation due to unexpected rusted bolts, poor access, etc. but he got the job done on time and on budget.

Duane

25 years of experience
510 reviews
Duane
25 years of experience
Ford Focus L4-2.3L - Serpentine/Drive Belt Replacement - Fallbrook, California
Serpentine belt and tensioner replacement. He also gave me great recommendations. He's really professional and courteous.

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