Engine - Lower End Knock On Acceleration
Article No.95-10-5
05/22/95
^ ENGINE - 3.0L - "KNOCKING" NOISE FROM LOWER END (# 1) MAIN BEARING DURING ACCELERATION
^ NOISE - "KNOCK" FROM LOWER END (# 1) MAIN BEARING DURING ACCELERATION - VEHICLES WITH 3.0L ENGINE
FORD:
1991-92 TAURUS
LINCOLN-MERCURY:
1991-92 SABLE
ISSUE:
A "knocking" noise from the lower front of the engine may be heard in the passenger compartment. The "knock" is most pronounced with the vehicle in gear, under a load, between 1200-1400 rpm with the engine hot or cold. This occurs because the front end accessory belt load combines with the # 4 cylinder firing to produce an audible noise in the # 1 front main engine bearing.
ACTION:
Convert the multiple Front End Accessory Drive (FEAD) system to a single belt "serpentine" accessory drive belt and replace # 1 front main bearings. Refer to the following Service Procedure for details.
NOTE:
THE FOLLOWING DIAGNOSTIC PROCEDURES SHOULD BE DONE IN A QUIET AREA AND AT NORMAL ENGINE OPERATING TEMPERATURE. A MAIN BEARING KNOCK IS A LOW FREQUENCY SOUND AND AUDIBLE AT NORMAL OPERATING TEMPERATURE.
SERVICE PROCEDURE
1. Disconnect "SPOUT" and verify ignition timing is 10° Before Top Dead Center (BTDC). Correct as required, reconnect "SPOUT".
2. Connect a suitable cylinder "shorting" device and tachometer.
NOTE:
A SERVICE BAY DIAGNOSTIC SYSTEM (SBDS) ANALYZER MAY BE USED TO RESTRICT FUEL TO A CYLINDER ON SEQUENTIAL FUEL INJECTED (SFI) ENGINES (1991-92), OR SHORT OUT A CYLINDER ON NON-SFI APPLICATIONS. RESTRICTING FUEL TO A CYLINDER IS THE MORE DESIRABLE METHOD.
3. Set the parking brake and block all wheels to prevent sudden movement of the vehicle and start engine.
a. Place foot on brake, shift into DRIVE and raise engine speed to 1200-1400 rpm.
Engine -V6-3Liter:
b. Place a listening device (mechanical or electronic stethoscope) perpendicular to the bottom of the engine on the machined boss at the front of the engine. Refer to Figure 1.
CAUTION:
MAINTAIN ENGINE RPM FOR 10-15 SECONDS ONLY TO DETERMINE IF FRONT BEARING KNOCK IS PRESENT. ANY LONGER THAN 15 SECONDS MAY OVERHEAT THE TRANSMISSION. TRANSMISSION FLUID SHOULD BE COOLED AFTER EVERY ENGINE BRAKE TORQUE. RUN THE TRANSMISSION IN NEUTRAL OR PARK FOR 10-15 SECONDS AT 1000-1500 RPM TO CIRCULATE THE TRANSMISSION FLUID AND COOL IT.
4. If knock is present, short out ignition or disconnect # 4 cylinder fuel injector connector and determine if knock is significantly reduced or eliminated.
CAUTION:
MAINTAIN ENGINE RPM WITH SPARK DISCONNECTED FOR 10-15 SECONDS ONLY, ANY LONGER THAN 15 SECONDS WILL PERMANENTLY DAMAGE THE CATALYST.
5. If knock is significantly reduced or eliminated, validate the diagnosis by removing all FEAD accessory belts and repeat Step # 3. Listen for front engine knock. Knock should be significantly reduced or eliminated.
CAUTION:
MAINTAIN ENGINE RPM A MAXIMUM OF 10-15 SECONDS ONLY WITH ACCESSORY DRIVE BELTS REMOVED, OR ENGINE WILL OVERHEAT.
6. Install the Single Belt Service Kit (F4PZ-8A630-A). Refer to the following Single Belt Service Kit contents listing and the Parts Block for correct parts usage. Refer to Instruction Sheet # 6507-A, included in each kit, for installation details.
Each Taurus/Sable Single FEAD Belt Service Kit contains the following components:
^ One (1) Engine Mount Assembly
^ Two (2) Bolts - Engine Mount-To-A/C Compressor
^ One (1) Nut - Engine Mount-To-Subframe
^ One (1) A/C Compressor Bracket
^ Four (4) Bolts - A/C Compressor Bracket-To-Block
^ One (1) A/C Compressor
^ One (1) A/C Compressor Hub
^ One (1) A/C Compressor Coil
^ One (1) A/C Compressor Pulley
^ Four (4) Bolts - A/C Compressor-To-A/C Compressor Bracket
^ One (1) Brace - A/C Compressor Bracket-To-Water Pump
^ One (1) Stud - Water Pump
^ One (1) Nut - Brace-To-Water Pump Stud
^ One (1) Crankshaft Pulley
^ Four (4) Bolts - Crankshaft Damper Pulley-To-Crankshaft Damper
^ One (1) Idler Assembly
^ One (1) Water Pump Pulley
^ Four (4) Screws - Water Pump Pulley-To-Hub
^ One (1) Power Steering And Alternator Bracket
^ One (1) Bolt - Power Steering And Alternator Bracket-To-Head
^ Two (2) Studs - Cylinder Head
^ Two (2) Nuts - Power Steering And Alternator-To-Stud
^ Three (3) Bolts - Power Steering Pump-To-Power Steering Bracket
^ One (1) Alternator
^ One (1) Bolt - Alternator-To-Power Steering Bracket
^ One (1) Brace - Alternator-To-Throttle Body
^ Two (2) Bolts - Brace-To-Alternator
^ One (1) Nut - Brace-To-Throttle Body
^ One (1) Auto Belt Tensioner
^ One (1) Accessory Drive Belt
^ One (1) Brace - Alternator-To-Cylinder Head
^ One (1) Accessory Drive Belt Wrap Decal
^ One (1) # 1 Upper Main Bearing
^ One (1) # 1 Lower Main Bearing
^ One (1) Oil Pan Gasket
^ One (1) Instruction Sheet (I.S. 6507-A)
PART NUMBER PART NAME
F4PZ-8A630-A Single FEAD Belt Service Kit
(Taurus/Sable)
OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage For 1992 Models, Powertrain Warranty Coverage For 1991 Models
OPERATION DESCRIPTION TIME
951005A Diagnose Knock, Retrofit 5.9 Hrs.
FEAD And Replace No. 1
Main Bearing
DEALER CODING
CONDITION
BASIC PART NO. CODE
6333 56
OASIS CODES: 497000, 702100