Engine - Buzz/Rattle/Low End Knock

Article No.
93-11-8

05/26/93

^ ACCELERATOR - 4.9L - NOISE FROM ACCELERATOR BRACKET/CABLE GROUND OUT

^ ENGINE - 4.9L - ACCELERATOR BRACKET/CABLE GROUNDS OUT

^ NOISE - "BUZZ" OR "RATTLE" BETWEEN 3000-3200 RPM ON NEUTRAL RUN UP OR DURING DRIVE CONDITIONS - VEHICLES WITH 4.9L ENGINE

^ NOISE - "LOW END KNOCK" AT 1200-1500 RPM FROM 4.9L ENGINE COMPARTMENT

LIGHT TRUCK:
1990-93 BRONCO, F-150-350 SERIES

ISSUE:
A "low end knock" noise from the engine area may be heard in the passenger compartment while the vehicle is in gear and under load. This occurs in the 1200 to 1500 rpm range whether the engine is hot or cold. A "buzz" or "rattle" may occur between 3000-3200 rpm on neutral run up or during drive conditions. These noises may be caused by the accelerator bracket/cable grounding out.

ACTION:
Install an accelerator bracket service kit. Refer to the following procedure for service details.

The accelerator bracket service kit (F4TZ-9728-JB) contains the following components:

^ One (1) accelerator cable bracket

^ One (1) splash shield bracket

^ One (1) A/C and power steering mounting bracket

^ One (1) stud

^ Three (3) bolts

^ One (1) Instruction Sheet # 6461A

1. Confirm that there is a "low end knock" noise heard in the passenger compartment. Refer to TSB 93-2-10.

2. Confirm that there is a "buzz" or "rattle" condition.

WARNING:
DO NOT STAND IN FRONT OF THE VEHICLE WHEN PERFORMING THIS STEP. MAKE SURE THE PARKING BRAKE IS APPLIED.

a. Hold the accelerator bracket firmly during neutral run up to the 3000-3200 rpm range.

b. If the "buzz" or "rattle" is gone, the bracket is the cause.

3. With the engine and ignition OFF, slowly press the accelerator pedal to the floor and verify that the linkage contacts the throttle stop (full throttle achieved).

4. With no load applied to the pedal, verify that the throttle linkage is in contact with the idle set screw.

5. If the bracket is the cause of the noise, install the accelerator bracket service kit (F4TZ-9728-JB). Follow the procedure outlined in Instruction Sheet # 6461A which is included in the kit.

PART NUMBER PART NAME CLASS

F4TZ-9728-JB Accelerator Bracket Service Kit BG

OTHER APPLICABLE ARTICLES:
93-2-10

WARRANTY STATUS:
Eligible Under Bumper To Bumper Warranty Coverage For 1992/93 Models, Basic Warranty For All Other Models

OPERATION DESCRIPTION TIME
931108A Install New Brackets 1.5 Hrs.
931108B Additional Time If Vehicle Is 0.1 Hr.
Equipped With Either Air
Conditioning, Speed Control
Or C6 Automatic Transmission

DEALER CODING
BASIC PART NO. CONDITION CODE
9728 56

OASIS CODES:
497000, 499000, 702000, 702100, 702300