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2017 · Chevrolet Silverado 1500 · Serpentine beltK2XX · 2014–2018

2014 to 2020 Chevrolet Silverado 1500 5.3L serpentine belt and tensioner

wrenchpitMaster TechAug 13, 2026

TIME

52m

DIFFICULTY

5/10 · Moderate — a careful afternoon

Tools

3/8 inch drive ratchet with a 15mm socket
3/8 inch drive breaker bar or a long handled ratchet for the tensioner
Torque wrench that covers 30 to 45 ft lbs
Belt routing diagram, printed or on your phone
Flashlight
Nitrile gloves

Parts

Serpentine belt — AC Delco 6K1042 (Gates K061042 / Dayco 5061042)
Belt tensioner assembly — AC Delco 12630523 (Gates 39399 / Dayco 89459)
Idler pulley, if worn — AC Delco 12626644 (Gates 36753)

Steps

01Park cool and pop the hood

Let the truck sit until the engine is cool to the touch. The tensioner arm sits close to the exhaust manifold on the passenger side, and hot metal on your knuckles is a bad way to start any job.

02Photograph the belt routing

Before you touch anything, take a phone picture of the belt routing from the front of the truck. The 5.3L belt loops around six pulleys and two idlers, and getting it wrong on reinstall is easy if you have not run this belt before. The routing sticker on the fan shroud is usually faded on trucks over five years old.

03Locate the tensioner

The tensioner sits at the top of the engine, driver side of center, above the water pump. It has a square 3/8 inch drive hole cast into the arm for a breaker bar. Slot the breaker bar into that hole.

04Rotate the tensioner to release belt tension

Pull the breaker bar counter-clockwise, looking at it from the front of the truck, to swing the tensioner arm and slacken the belt. Hold it there with your left hand. The spring inside the tensioner is strong, and if the bar slips out under load it will snap back and clip your knuckles.

05Slip the belt off the alternator pulley

With the belt slack, slide it off the alternator pulley first, which is the easiest one to reach from above. Let the tensioner arm return slowly, then work the belt off the remaining pulleys.

06Inspect the idlers and tensioner

Spin the tensioner pulley and any smooth idler pulleys by hand. Listen for grit or roughness in the bearings and feel for side to side wobble. Look at the tensioner arm and see if it swings smoothly through its full range. Any bearing noise or wobble is your signal to replace that part now, while the belt is off.

07Unbolt the old tensioner

If the tensioner is going in, a single 15mm bolt in the center of the tensioner holds it to the front cover. Break it loose, spin it out, and pull the tensioner off. Note the alignment tab on the back that indexes into a hole in the cover so you seat the new one correctly.

08Install the new tensioner

Line up the alignment tab on the back of the new tensioner with the hole in the front cover and start the 15mm bolt by hand. Please check your service manual, but the torque spec on the tensioner mounting bolt is 37 ft lbs (50 Nm).

09Route the new belt

Follow the photo you took at step 2. Route the new belt around every pulley except the alternator, saving that one for last. Double check every ribbed pulley to confirm the belt ribs sit down into the grooves and the flat side rides on the two smooth idlers.

10Rotate the tensioner and slip the belt on the alternator

Rotate the tensioner counter-clockwise with the breaker bar to make room, and slide the belt over the alternator pulley. Ease the tensioner back and confirm the belt is centered on every pulley, all ribs seated.

11Start the truck and verify

Pull the breaker bar out, close the hood, and start the truck. Let it idle and listen. A properly routed belt runs silent. Any chirp or squeal means a rib is off, and you need to shut it down and reseat the belt before you drive off.

Notes

Reference guide — verify every torque figure before you rely on it. This is a general procedure compiled by Wrenchpit, not a first-hand write-up from one owner's vehicle. The fastener torques below are commonly cited values, not measured ones, and they vary by model year, engine and trim. This job involves fasteners where an incorrect torque can cause a component to come loose in service. Look the figures up in your service manual and use a calibrated torque wrench. Part numbers should be checked against the labels on your old parts.

Applies to roughly 2014–2020 model years. Filed under 2017 because a guide carries one model year; check the range above.

The 5.3L V8 belt system on the K2XX generation is well laid out and one of the easier serpentines to service in the truck world, mostly because GM gave the tensioner arm a proper square drive hole so you do not need a special tool. The whole job is under an hour once you have done it once, and parts run 45 to 90 dollars for a good belt plus tensioner.

Replace the tensioner and the belt together as a rule. A worn tensioner spring lets the belt flap under load, which chirps and wears the belt ribs unevenly. If you put a new belt on a tired tensioner, you will be back in there in 20,000 miles wondering why the new belt looks used.

Check the idler pulleys by hand every time. The upper smooth idler bearing on this engine is a common weak point. It gets hot from its proximity to the exhaust and starts to whine around 100,000 miles. If you feel any roughness or hear a bearing hum with a mechanic stethoscope on the pulley bolt, replace it while everything is apart.

Watch for coolant weeping at the water pump seal above the tensioner. The 5.3L water pump lives right there, and belt swaps are a good time to catch a pump that is starting to seep. A pump that is weeping now will fail hard in another 10,000 miles.

Check your part numbers against the labels on the old belt and the old tensioner box before you order. GM ran a couple of different belt lengths across the 14-20 Silverado depending on whether the truck has the AFM 5.3L, the non-AFM 5.3L, or an aftermarket delete kit, and the tensioner casting numbers changed mid run.

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