Automatic Belt Tensioner - Pulley Wear

89ford21

ACCESSORY DRIVE BELT-4.9L, 5.0L, 5.8L AND 7.5L ENGINES-AUTOMATIC BELT TENSIONER PULLEY WEAR-SERVICE TIP

Article No. 89-14-19

LIGHT TRUCK: 1988-89 BRONCO, ECONOLINE, F-150, F-250, F-350 1989 F SUPER DUTY

This TSB article is being republished in its entirety to correct the dealer coding. Also technicians should use a wrench instead of a socket and rachet when positioning the tensioner assembly to the free arm stop.

ISSUE: The plastic idler pulley on the automatic belt tensioner may show signs of abnormal wear sooner than expected if the truck is used in a lot of off-road type driving. Off-road driving often results in more dust and dirt getting into the engine compartment. The dirt causes the plastic idler pulley and accessory drive belt to wear at a faster rate.

ACTION: It is no longer necessary to replace the entire automatic belt tensioner assembly to repair worn idler pulleys. The plastic idler pulley is now serviced separately. Refer to the following procedure for service details.

1. Remove the accessory drive belt. Refer to the 1988 or 1989 Light Truck Shop Manual, Volume B, Section 27-06 for service details.

NOTE: USE A WRENCH TO POSITION THE IDLER ASSEMBLY TO THE FREE ARM STOP. DO NOT USE A SOCKET AND RACHET TO PERFORM THIS STEP.

2. Slowly lower the tensioner arm to the free arm stop position.

CAUTION: DO NOT LET THE ARM SPRING BACK TO THE STOP OR THE TENSIONER COULD BE DAMAGED.

3. Using a 5/8 inch or 16 mm wrench, remove the idler pulley bolt.

CAUTION: THE IDLER PULLEY BOLT ON 5.0L, 5.8L AND 7.5L ENGINES HAVE A LEFT HAND THREAD THAT REQUIRES A CLOCKWISE MOTION TO LOOSEN. THE IDLER PULLEY BOLT ON THE 4.9L ENGINE HAS A CONVENTIONAL THREAD WHICH LOOSENS IN THE NORMAL COUNTER CLOCKWISE DIRECTION. TRYING TO TURN THE BOLT IN THE WRONG DIRECTION MAY DAMAGE THE TENSIONER ARM CASTING.

4. Remove the bolt and the dust shield. The pulley slips off the tensioner arm locating boss.

5. Install the new idler pulley.

6. Tighten the retaining bolt to a torque of 55-65 (ft.lbs. (6.2-7.3 N-m).

7. Check the condition of the accessory drive belt, replace as required.

8. Reinstall the accessory drive belt. Refer to the 1988 or 1989 Light Truck Shop Manual, Volume B, Section 27-06 for service details.

PART NUMBER PART NAME CLASS

E8TZ-8678-D Pulley Assembly - Belt - B
5.0L/5.8L Engine
E8TZ-8678-E Pulley Assembly - Belt - B
4.9L/7.5L Engines

OTHER APPLICABLE ARTICLES: None
SUPERSEDES: 89-10-11, date 6/1/89
WARRANTY STATUS: Eligible Under Basic Warranty Coverage

OPERATION DESCRIPTION TIME
891419A E-Series 0.4 Hr.
891419A F-Series & Bronco 0.3 Hr.

DEALER CODING
BASIC PART NO. CONDITION CODE
6B209 30
OASIS CODES: 4700