Issue With Mustang's A/C Belt

Some 2011-2012 Ford Mustangs equipped with a 5.0L engine and air conditioning (A/C) compressor “stretchy belt” may exhibit a light, lower-end knock that is most noticeable when the engine temperature is warm and the vehicle is at idle.

1. Remove the A/C compressor stretchy belt. Start the engine and re-evaluate the concern. If the knock is still present, continue with diagnostics. If the knock is gone, obtain the drive belt service kit. 

2. For vehicles with automatic transmission, also obtain transmission fluid cooler tubes and clamps. 

3. Determine engine build date. If the build date is on or before April 15, 2011, proceed to Step 4. If after April 15, 2011, do not replace the engine front cover. Use an 8 x 1.25mm tap to clean the mounting locations for the front cover. Clean with compressed air. For vehicles equipped with an automatic transmission, proceed to Step 5. With manual transmission proceed to Step 6.

4. Replace the front engine cover.

5. For vehicles with automatic transmission, install new transmission fluid cooler tubes.

6. Install the A/C compressor drive belt idler pulley and A/C compressor drive belt idler pulley bolt supplied in the service kit. Tighten to 18 ft-lb.

7. Install the compressor drive belt tensioner from the kit. Tighten to 18 ft-lb.

8. Install the compressor drive belt from the kit.

9. Install the accessory drive belt.

10. Install IDS (integrated diagnostic system) and identify the vehicle. Answer IDS screen prompts according to the current vehicle A/C belt configuration.

11. Reprogram the PCM using IDS release 79.03 or higher.

12. Perform misfire monitor neutral profile correction. Select IDS toolbox icon, powertrain, service functions, then misfire monitor neutral profile correction.

P/N                                     PART

CR3Z-8620-AA......................... drive belt kit – Boss

BR3Z-8620-DA......................... drive belt kit – GT

BR3Z-6019-G........................... front cover

XW4Z-6700-AA........................ front crankshaft seal

CR3Z-7R081-D......................... trans. cooler tube assembly

8C2Z-7C107-A.......................... oil cooler clamps

CR3Z-7R081-C.......................... trans. cooler tube assembly