Replacing a Serpentine Belt and Tensioner

Here’s a typical General Motors V6 engine that needs a serpentine belt and belt tensioner replaced. Follow the step by step illustration with helpful information needed to diagnose belt and tensioner problems as well as how to replace the belt and tensioner assembly.

This is the same 1995 Monte Carlo used in the compression test post. In the last 10-15 years General Motors vehicles have kept the same drive belt design on the V6 engines. Why change a good thing if it works? From the cars to vans the amount of room may vary, but the routing and spring type tensioner is the same. When changing the belt and tensioner the procedure will not change.

Reasons for Replacement

Belts wear and need to be changed due to visible cracks and possible breakage of the belt or they become noisy from drying out due to age. The tensioners can fail from the bearings in the roller wearing out and becoming extremely noisy or locking up. The spring mechanism can also come apart and cause the belt to jump off the pulleys. Either way, they both can be repaired/replaced.

Tools to be Used

• 3/8″ long handle ratchet
• 13mm socket

Visual Inspection

Here is a belt and tensioner assembly. The belt tension is applied automatically by the spring inside the tensioner and no adjustments are needed. This is how the manufacture designed this type of system.

Take note of the routing the belt takes around each pulley for installation before you remove the old belt.

In order to remove the belt, the spring tension must be released.

Here at the end of the roller there is a 3/8″ square flange designed for a ratchet to aid in belt removal.

Here’s a better look at the tensioner through a mirror.

Belt Removal

Install ratchet into tensioner

Pull tensioner counter clockwise enough to remove belt from top pulley groove.

Trace the belt routing on a piece of paper or look for a diagram on the car. This is to help you remember the route when installing the new belt.

Remove the old belt from pulleys.

Remove Tensioner

Remove the 13mm bolt holding the tensioner to the engine.

Here’s a better look at the tensioner and ratchet off the car.

Estimate for Repair

(check with your local parts stores for current prices)
Parts to replace
Drive belt – If needed, approximately $15-$40 (depending on brand)
Belt tensioner – tensioner w/pulley, $52
Belt pulley – pulley only, approximately $25
Total parts for belt and tensioner assy. from your local parts store, $92 plus tax
Labor to replace
If paid to have replaced approximately 1 hr. labor ($80)
Parts and Labor
Total parts and labor, $172

Time to replace – a realistic amount of time depends on the type of vehicle with this engine.
Worst case scenario, 45 minutes.
Best case scenario, 15 minutes