Engine - Knocks At Idle When Warmed Up
Section Title: EngineTSB No. TS 22 04239R
Division: Automotive
Category: Technical
Revision:
Note added to adjustment methods.
SUBJECT:
ENGINE KNOCKS AT IDLE WHEN FULLY WARMED UP: DRIVE BELT TENSION CHANGE.
MODEL(S): GRAND VITARA (JB627)
YEAR: 2006~2008
AFFECTED VIN(S):
VEHICLES UP TO PRODUCTION DATE OF JULY 9, 2007
CONDITION:
After the engine completely warms up a knocking noise can be heard from the bottom of the engine.
CAUSE:
Mis-adjusted drive belt tension will cause the engine crank shaft to abnormally oscillate, which can produce an audible knock sound, similar to excessive bearing clearance noise (bottom end knock).
NOTE:
The mis-adjusted belt will not result in internal engine damage.
CORRECTION:
The tension of the water pump/alternator belt was changed in production from 700N to 650N to reduce this audible knock. Use one of the two procedures below to adjust the drive belt tension of the water pump / alternator belt to the new specification found in the instructions. Also verify the tension is correct on the power steering / A/C belt. Engine should be cold when adjustment is made. Adjustments of the drive belts using the values in this TSB will minimize the noise heard.
PART(S) INFORMATION/WARRANTY INFORMATION
Drive Belt Tension Adjustment Procedure
Water Pump/Alternator Drive Belt Tensioner Adjustment Procedure.
1. Loosen bolt (2) and remove tension pulley bolt (1).
2. Insert hex wrench into the exposed hex hole of the tensioner pulley (3). Rotate the wrench as shown to adjust belt tension to the desired specification. Refer to one of the two desired tension check methods shown under "Tension Check Method".
3. Hold the tension with the hex wrench (4) and tighten tensioner bolt (2). Remove the hex wrench and install bolt (1), and torque the tensioner bolts properly.
a. Tightening torque: 25 Nm (18 lb-ft)
4. Start the engine and run for approximately 2-3 seconds then stop it.
5. Recheck the belt tension. Re-adjust if the tension does not meet specification.
Power Steering/Air Conditioner Belt Adjustment Procedure.
1. Loosen tensioner pulley (3) bolts (1,(a).
2. Using a hex wrench (4), rotate the tensioner pulley to tighten (6), or loosen (5) the tension adjustment as needed.
3. Refer to one of the two desired tension check methods shown under "Tension Check Method".
4. Hold the tension with the hex wrench (4) and tighten tensioner bolts (1,(a)). Torque the tensioner bolts properly.
a. Tightening torque: 25 Nm (18 lb-ft)
5. Start the engine and run for approximately 2-3 seconds then stop it.
6. Recheck the belt tension. Re-adjust if the tension does not meet specification.
Tension Check Methods
Method 1 (Torque Wrench)
Water Pump/Alternator Drive Belt Tensioner Adjustment Procedure.
Attach appropriate sized hex socket to torque wrench (dial type with telltale preferred) and apply torque listed in the table above to belt tensioner. Refer to figure 1 and 2 for hex location and tightening and tightening direction.
Method 2 (Sonic Tension Meter)
Water Pump/Alternator and Power Steering/AC Belts
Use the Gates(R) Sonic Tension Meter(R) 507C.
Follow the instructions enclosed with the tension meter for set up and operation.
Set frequency filter setting as "Standard" with the data above.