What is adjusted in order to replace serpentine belt or tighten belt on 1997 GMC 454 3500 Truck? The air pump had siezed up- so I removed pulley and now have slack. Thanks in advance. Art

• Located front of engine, close to crank pulley
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• Insert the square tip of a 1/2-inch socket wrench into the square hole in the center of the serpentine belt's adjustment pulley. The adjustment pulley is the smallest pulley the belt wraps around.
• Pull the adjustment pulley toward the engine with the socket wrench to release the tension on the serpentine belt, then pull the belt off the air conditioning compressor's pulley.
• Remove the bolts which secure the air conditioning compressor to its mounting brackets with an open-end wrench, then position the compressor to the side of the engine compartment. Do not disturb the hoses that attach to the compressor.
• Pull the electrical connection off the crankshaft sensor.
• Remove the two bolts that secure the crankshaft sensor against the engine with an open-end wrench, then slide the sensor out of the engine.
• Slide the new crankshaft sensor into the engine, then install and tighten the sensor's two securing bolts with an open-end wrench.
• Press the electrical connection onto the crankshaft sensor.
• Position the air conditioning compressor against its mounting brackets, then install and tighten the compressor's bolts with an open-end wrench.
• Pull the serpentine belt's adjustment pulley toward the engine with the socket wrench, then position the belt onto the air compressor's pulley. write up found @ehow

How to Replace the Crankshaft Sensor in Ford 150 eHow

ADJUSTMENT

Excessive belt tension will cause damage to the alternator and water pump pulley bearings, while, on the other hand, loose belt tension will produce slip and premature wear on the belt. Therefore, be sure to adjust the belt tension to the proper level.
To adjust the tension on a drive belt, loosen the adjusting bolt or fixing bolt locknut on the alternator, alternator bracket or tension pulley. Then move the alternator or turn the adjusting bolt to adjust belt tension. Once the desired value is reached, secure the bolt or locknut and recheck tension.

REMOVAL & INSTALLATION

1.5L, 1.6L, 1.8L, 2.0L and 2.4L Engines

Fig. Accessory V-belt routing-Mitsubishi 1.5L, 1.6L, 1.8L, 2.0L and 2.4L engines
Alternator Belt

Fig. Loosen the adjuster lock bolt . . .

Fig. . . . then remove the alternator belt from the engine

1. Loosen the alternator support nut.
2. Loosen the adjuster lock bolt.
3. Rotate the adjuster bolt counter clockwise to release the tension on the belt.
4. Remove the belt.

To install:

1. Install the belt on the pulleys.
2. Rotate the adjuster bolt clockwise until the proper tension is reached.
3. Tighten the adjuster lock bolt and the alternator support nut.

POWER STEERING BELT

Fig. After the adjusting and fixed bolts are loosened, rotate the pump . . .

Fig. . . . then remove the power steering belt from the engine

1. Remove the alternator belt as described above.
2. Loosen the power steering pump adjusting bolts.
3. Remove the power steering pump fixed bolt on the rear of the bracket.
4. Rotate the pump toward the engine and remove the belt.

To install:

1. Install the belt on the pulleys.
2. Rotate the pump until the proper tension is reached.
3. Tighten the adjusting bolts on the pump.
4. Tighten the fixed bolt on the rear of the bracket.
5. Install the alternator belt.

A/C COMPRESSOR BELT

1. Loosen the tension pulley and remove the belt.
2. The installation is the reverse of the removal.

3.0L DOHC, 3.0L SOHC Galant, and 3.5L Engines

Fig. Serpentine belt routing-Mitsubishi 3.0L engines (except 1998-00 Galant models)

Fig. Accessory V-belt routing-Mitsubishi 3.5L and 1998-00 3.0L SOHC Galant engines
ALTERNATOR AND A/C COMPRESSOR

1. Disconnect the negative battery cable.

CAUTION Wait at least 90 seconds after the negative battery cable is disconnected to prevent possible deployment of the air bag.

1. Raise and safely support the vehicle and remove the front undercover.
2. Loosen the tension pulley fixing nut and relieve the tension on the belt by turning the adjusting bolt.
3. Remove the belt.

To install:

1. Install the belt on the crankshaft and alternator pulleys.
2. Using the adjusting bolt on the tensioner, tighten the belt to the desired tension.
3. Tighten the fixing nut to hold the adjustment.
4. Install the undercover and lower the vehicle to the floor.
5. Connect the negative battery cable.

POWER STEERING BELT

1. Disconnect the negative battery cable.

CAUTION Wait at least 90 seconds after the negative battery cable is disconnected to prevent possible deployment of the air bag.

1. Raise and safely support the vehicle and remove the undercover.
2. Remove the alternator and A/C compressor belt.
3. Lower the vehicle and remove the cruise control pump link assembly.
4. Place the power steering hose under the oil reservoir.
5. Loosen the tension pulley fixing bolts and remove the power steering pump drive belt.

To install:

1. Install the power steering pump drive belt.
2. Insert an extension bar or equivalent into the opening at the end of the tension pulley bracket and pivot the pulley to apply tension to the belt.
3. Tighten the fixing bolts.
4. Raise the vehicle and install the alternator and A/C compressor belt.
5. Install the undercover and lower the vehicle.
6. Connect the negative battery cable.

3.0L SOHC Diamante

1. Disconnect the negative battery cable.
2. Loosen the lockbolt on the face of the A/C tensioner pulley.
3. Turn the adjusting bolt of the A/C tensioner pulley to loosen the tension of the A/C belt.
4. Remove the A/C compressor belt.
5. Loosen the locknut on the face of the power steering/alternator tensioner pulley.
6. Turn the adjusting bolt of the tensioner pulley to loosen the tension of the belt.
7. Remove the power steering/alternator belt.

To install:

1. Install the power steering/alternator belt first and then the A/C compressor drive belt.
2. Adjust the belts to the proper tension by turning the adjusting bolts and tighten pulley fixing nut/bolt.
3. Tighten the mounting nut of the power steering/alternator tensioner pulley to 36 ft. lbs. (50 Nm).

Which engine?

1. Drain the radiator

1. Loosen the water pump pulley bolts.
2. Remove the serpentine belt.

1. Remove the water pump pulley bolts and pulley.
2. Remove the water pump bolts, pump and gasket.
3. Clean the water pump mating surfaces.

Installation Procedure

1. Install the water pump gasket and pump.

1. Install the water pump bolts. Tighten the water pump bolts to 89 inch lbs.

Install the water pump pulley and bolt until snug.

Install the serpentine belt.

Tighten the water pump pulley bolts. Tighten the water pump pulley bolts to 18 ft. lbs.

Fill the cooling system and purge of air.

Inspect for leaks.

Remove the alternator/power steering pump and water pump drive belt to gain access to the air conditioning drive belt.
To remove and install the air conditioning compressor drive belt, first loosen the tensioner pulley lock nut, then turn the adjusting screw to raise or lower the tensioner pulley assembly Accessory Drive - 3.3L Engine or Accessory Drive - 3.5L Engine To adjust the air conditioning drive belt, loosen the tensioner pulley nut and adjust belt tension by tightening adjusting screw. Torque pulley nut to 54 N•m (40 ft. lbs.) after adjustment.
The Poly-V generator/power steering belt has an adjustable tensioner pulley located on the timing belt cover Accessory Drive - 3.5L Engine to maintain proper belt tension. To remove or install this belt, Release tension by loosening the tensioner pulley nut and adjustment bolt Accessory Drive - 3.5L Engine Reverse procedure to install and tighten belt to specified tension.

2.8L and 3.1L Air Pump Belt

1. Disconnect the negative battery cable.
2. Loosen the air pump.
3. Remove the worn belt.

To install:

1. Adjust the belt to specifications and tighten the pump mounting bolts.
2. Connect the negative battery cable.

2.3L Power Steering Belt

1. Disconnect the negative battery cable.
2. Loosen the adjustment bolts.
3. Remove the power steering belt from the pulley.

To install:

1. Route the belt around the pulley.
2. Adjust the belt to specifications, then tighten the adjustment bolts.
3. Connect the negative battery cable.

See Figures 6 through 15

Fig. Fig. 6: Unfasten the retaining bolts...

Fig. Fig. 7: ... then remove the serpentine belt guard

Fig. Fig. 8: ...

Fig. Fig. 9: ... then remove the serpentine belt

1. Remove the belt. Clean the accessory drive belt surfaces.

Fig. Fig. 10: Serpentine drive belt routing-2.2L engine

Fig. Fig. 11: Removal and installation of the serpentine belt-2.3L engine

Fig. Fig. 12: Serpentine belt routing-2.5L engine with and without A/C

Fig. Fig. 13: Use an 18mm box end wrench on the pulley nut to rotate the tensioner on the 3.8L engine

Fig. Fig. 14: in. breaker bar to rotate the tensioner

Fig. Fig. 15: On the 3.4L, use a box end wrench, then rotate the tensioner clockwise and remove the serpentine belt

Remove the belt guard or coolant recovery reservoir as required.

Do you mean the tensioner pulley?

Then, I would look for something with a 1/2" square hole in a pivoting spring loaded pulley that is designed to put 'tension' on the serpentine belt.

Depending on the engine, it can be located in various positions.

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REMOVAL & INSTALLATION - 8 cylinder engine Alternator Belt

1. Loosen the alternator mounting and adjusting arm bolts.
2. Pivot the alternator inward and remove the belt from the vehicle. To install:
   
3. Install a new belt.
4. Holding the alternator in place to maintain tension, tighten the alternator mounting and adjusting arm bolts.

Power Steering Belt

1. Loosen the adjusting and mounting bolts on the front face of the steering pump cover plate (hub side).
2. Pivot the power steering pump inward and remove the drive belt. To install:
   
3. Install the drive belt.
4. Holding the pump in place, tighten the adjusting arm bolt and the mounting bolts.

Air Conditioning Compressor Belt

1. If the engine is equipped with an idler pulley, loosen the idler pulley adjusting bolt and remove the belt.
2. If not equipped with an idler pulley, loosen the adjusting and mounting bolts.
3. Pivot the air conditioning compressor inward and remove the drive belt.
4. Installation is the reverse of removal.

Air Pump Drive Belt

1. Loosen the adjusting arm bolt slightly. If necessary, also loosen the mounting bolt slightly and remove the drive belt. To install:
   
2. Holding the pump in place, install the drive belt, then tighten the adjusting arm bolt and the mounting bolt.

Noise could be the result of a dried out belt, a belt that needs adjustment or any one of the pulleys driven by the belt. The oil pump has nothing to do with the belt. Inspect it and try tightening it up a bit. If that does not help, remove the belt and check all the pulleys for noise and rough turning, replace the belt and re-tighten.

there are four nuts that you must remove at the front of the pulley between the fan. remove fan, fan shroud,loosen accessory belts. remove water pump pulley and the pump bolts will be exposed. check belts for replacement while you have them loose. reverse procedure to install.

The text below is from the GM Service manual 4.3L V6 Engine
Water Pump Replacement (4.3L)
Removal Procedure
Drain the cooling system. Refer to Draining and Filling Cooling System .
Loosen the water pump pulley bolts.
Remove the cooling fan and clutch assembly.

Tools Required
J 46406 Fan Clutch Wrench

Removal Procedure
Remove the upper fan shroud.
Remove the fan clutch from the water pump in a counterclockwise direction using the J 46406 .
Remove the fan clutch assembly.
Remove the drive belt. Refer to Drive Belt Replacement Remove the water pump pulley mounting bolts.
Remove the water pump pulley.
Remove the radiator outlet hose clamp from the water pump.
Remove radiator outlet hose from the water pump.
Remove the water pump mounting bolts.
Remove the water pump from the engine.
Remove the water pump gaskets.
Clean the water pump gasket mating surfaces.
Installation Procedure
Install the water pump gaskets.
Install the water pump to the engine.
Apply a sealer (GM P/N 12346004) to the bolt threads.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the water pump mounting bolts.
Tighten
Tighten the mounting bolts to 41 N·m (30 lb ft).
Install the radiator outlet hose to the water pump.
Install the water pump pulley.
Install the water pump pulley bolts.
Tighten
Tighten the water pump pulley bolts to 25 N·m (18 lb ft).
Install the drive belt. Refer to Drive Belt Replacement in Engine Mechanical - 4.3L.
Install the fan clutch assembly.
Fill the radiator cooling system. Refer to Draining and Filling Cooling System .
Inspect the cooling system for leaks.