How to Change the Serpentine Belt, Tensioner, & Idler Pulley on a 2009 to 2014 Ford F-150

Your Ford F-150’s serpentine belt, tensioner, and idler pulley are important parts of your truck’s belt drive and accessory operation. With proper tension, the serpentine belt uses movement from the crankshaft pulley to power the accessory drive on your truck, which includes the alternator, water pump, A/C compressor, and power steering pump. If you notice a cracked, loose, or worn belt, excessive belt noise, or shallow grooves on the pulley contact surface of the belt, you may have a failing or worn serpentine belt that will need to be replaced. A broken serpentine belt can cause engine overheating, a lack of power steering or A/C, or stalling that could leave you stranded. It is suggested that you replace the serpentine belt, idler pulley, and belt tensioner at the same time since they are often the same age and will likely have the same amount of wear. Our step-by-step instructions will help you perform a serpentine belt replacement on your Ford F-150.


Remove the Serpentine Belt, Tensioner, and Idler Pulley

Additional Resources

Tools & Materials

Safety Eye Glasses Safety Glasses

Protective Gloves Nitrile Gloves

ratchet Ratchet

Sockets for changing spark plugs Sockets

Breaker Bar Breaker Bar

Serpentine Belt Serpentine Belt

Tensioner Tensioner

Idler Pulley Idler Pulley

Step-by-Step Instructions to Replace Your Serpentine Belt, Tensioner, and Idler Pulley

Today, we’ll be changing the engine serpentine belt, tensioner and idler pulley, as well as the AC belt and tensioner on this 2012 Ford F-150. Procedures will be similar on a lot of 5-liter F-150s from 2009 to 2014, but be sure to know the specifics for your truck before getting started. If you’re not completely comfortable doing this yourself, we’d be happy to recommend a professional technician in your area.

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Remove the Serpentine Belt, Tensioner, and Idler Pulley

Mechanic opening the hood of a 2012 Ford F-150

Step 1: Prepare the Vehicle

Park on a level surface and open the hood.
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Man using a 13mm socket and ratchet to remove the air intake tube

Step 2: Remove the Air Intake Tube

For easier access, disconnect the hoses and electrical connector. Then remove the air intake tube.
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Man using a breaker bar to remove the main serpentine belt from a Ford F-150

Step 3: Remove the Main Serpentine Belt

To remove the main serpentine belt connected to your alternator, use your breaker bar and a 13mm socket on the tensioner pulley bolt and rotate counterclockwise to relieve tension on the belt. Then slide the belt off of the pulleys.
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Mechanic using a ratchet to remove the tensioner

Step 4: Remove the Tensioner

If you intend to replace the AC belt, you’ll also have to remove the main serpentine belt tensioner using a 13mm socket.
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If Your AC Compressor Belt Uses a Tensioner

Mechanic using a breaker bar to remove the AC Compressor Belt

Step 5: Remove the AC Compressor Belt

If your AC compressor belt uses a tensioner, here’s what you’ll do: Insert the end of your breaker bar into the opening on the tensioner. You may need to use an extension to reach it. Then, rotate the tensioner clockwise to relieve tension on the belt. Once tension has been relieved, you can remove the belt.
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Ratchet and socket being used to remove the tensioner

Step 6: Remove the AC Compression Belt Tensioner

If you are also replacing the tensioner, which is usually advised when the belt is replaced, it can also be removed with a 10mm socket.
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Man using a ratchet to remove the old idler pulley

Step 7: Replace the Idler Pulley

We also recommend the idler pulley be replaced if it’s worn or if the tensioner and belt and being replaced to ensure a complete, long-lasting repair.

To repair the idler pulley, loosen and remove the bolt and idler pulley.
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Install the New Serpentine Belt, Tensioner, and Idler Pulley

Mechanic installing a new idler pulley

Step 8: Install the New Idler Pulley

Install a new idler pulley and then torque it to 18 foot pounds.
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Mechanic using a ratchet to install a new AC Belt Tensioner

Step 9: Install the New AC Belt Tensioner

Now you can replace the AC Belt Tensioner with your new one and torque the bolt to 18 food pounds.
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Mechanic holding a ratchet and socket to the new AC belt tensioner

Step 10: Reroute Your New AC Belt

To reinstall the AC belt, route it around the compressor, then the tensioner, then the crankshaft. Use your breaker bar to rotate the AC belt tensioner arm clockwise and slip the belt over the tensioner.



Do It Right: Ensure that the belt is routed properly and is fully seated before moving back the accessory belt.

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Large ratchet with 14mm socket torqueing a bolt on the new tensioner

Step 11: Install the New Tensioner

Before reinstalling the new serpentine belt, install your new tensioner using a 14mm socket, and torque the bolt to 35 foot pounds.
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Man using a breaker bar to rotate the tensioner counterclockwise

Step 12: Reroute the New Serpentine Belt

Now, route your belt according to the belt routing diagram in your owner’s manual or under the hood. Starting with the crankshaft, alternator, and then tensioner. Insert your drive breaker bar or ratchet with a 15mm socket into the tensioner and rotate it counterclockwise. Then, loop the belt over the idler pulley.
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Man holding air intake tube over the engine and then using a ratchet to tighten the electrical connectors

Step 13: Reinstall the Air Intake Tube

Reinstall the air intake tube.
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Additional Resources

comparing old and new air filter

How to Install an Air Filter on a 2015 to 2020 Ford F-150
Thermostat

How to Replace the Water Pump on a 2009 to 2017 Ford F-150
removing cabin air filter from dash

How to Change the Cabin Air Filter on a Late Model Ford F-150

These step-by-step instructions and video detail a serpentine belt replacement on a 2012 Ford F-150 XLT, and will be similar for Ford F-150 models equipped with a 5.0-liter engine from 2011, 2013, 2014, 2015, and 2016, which includes the King Ranch, Lariat, Platinum, XL, STX, FX2, and FX4 submodels. The replacement procedures will be similar to Ford Focus models with a 2.0-liter engine from 2000 - 2011, Ford Mustang models from 2011- 2016, and Jeep Wrangler models from 2000 to 2006. Replacing a damaged or failing serpentine belt, tensioner, or idler pulley helps you maintain a safe, functioning drive belt system and keeps the belt driving your accessories. If you notice your truck is making excessive squealing noises from under the hood, overheating, or if you see cracks or damage on the serpentine belt, it should be replaced. The belt tensioner or idler pulley may also seize and result in a loose belt or belt damage, and you should perform a full serpentine belt and belt tensioner replacement to keep your truck running right.

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The automotive repair work depicted in this series is performed under the direction of the manufacturer of the product featured. Prior to undertaking any of the demonstrated repairs on your vehicle, we suggest you consult with a certified mechanic or another professional who can adequately advise you of the proper repair or remedy required. O’Reilly Automotive Stores, Inc. and its affiliates (“O’Reilly”) disclaims any responsibility for injury or damage resulting from a viewer’s attempt to recreate the repairs shown in this series.