Engine Mechanical - 4.3L: Overview Chevrolet Blazer S15 facelift

Results Of Incorrect Operation

1. A plugged valve or hose may cause the following conditions: Rough idle Stalling or slow idle speed Oil leaks Oil in air cleaner Sludge in engine
2. A leaking crankcase ventilation valve or hose may cause the following conditions: Rough idle Stalling High idle speed

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2. The noise may not be engine related. This step is to verify that the engine is making the noise. If the engine is not making the noise do not proceed further with this table.
2. 3. The noise may be an internal engine noise. Removing the drive belt and operating the engine for a brief period will verify the noise is related to the drive belt. When removing the drive belt(s) the water pump may not be operating and the engine may overheat. Also DTCs may set when the engine is operating with the drive belt removed.
3. 4. Inspect all drive belt pulleys for pilling. Pilling is the small balls or pills or it may be strings in the drive belt grooves from the accumulation of rubber dust.
4. 6. Misalignment of the pulleys may be caused from improper mounting of the accessory drive component, incorrect installation of the accessory drive component pulley, or the pulley bent inward or outward from a previous repair. Test for a misalign pulley using a straight edge in the pulley grooves across two or three pulleys. If a misalign pulley is found refer to that accessory drive component for the proper installation procedure for that pulley.
5. 10. Inspecting of the fasteners can eliminate the possibility that a wrong bolt, nut, spacer, or washer was installed.
6. 12. Inspecting the pulleys for being bent should include inspecting for a dent or other damage to the pulleys that would prevent the drive belt from not seating properly in all of the pulley grooves or on the smooth surface of a pulley when the back side of the belt is used to drive the pulley.
7. 14. Replacing the drive belt when it is not damaged or there is not excessive pilling will only be a temporary repair.

Scheme 357

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2. The noise may not be engine related. This step is to verify that the engine is making the noise. If the engine is not making the noise do not proceed further with this table
2. 3. The noise may be an internal engine noise. Removing the drive belt and operating the engine for a brief period will verify the squeal noise is the drive belt(s) or an accessory drive component. When removing the drive belt the water pump may not be operating and the engine may overheat. Also DTCs may set when the engine is operating with the drive belt removed.
3. 4. This test is to verify that an accessory drive component does not have a seized bearing. With the belt remove test the bearings in the accessory drive components for turning smoothly. Also test the accessory drive components with the engine operating by varying the load on the components to verify that the components operate properly.
4. 5. This test is to verify that the drive belt tensioner operates properly. If the drive belt tensioner is not operating properly, proper belt tension may not be achieved to keep the drive belt from slipping which could cause a squeal noise.
5. 6. This test is to verify that the drive belt(s) is not too long, which would prevent the drive belt tensioner from working properly. Also if an incorrect length drive belt was installed, it may not be routed properly and may be turning an accessory drive component in the wrong direction.
6. 7. Misalignment of the pulleys may be caused from improper mounting of the accessory drive component, incorrect installation of the accessory drive component pulley, or the pulley bent inward or outward from a previous repair. Test for a misalign pulley using a straight edge in the pulley grooves across two or three pulleys. If a misalign pulley is found refer to that accessory drive component for the proper installation procedure for that pulley.
7. 8. This test is to verify that the pulleys are the correct diameter or width. Using a known good vehicle compare the pulley sizes.

Scheme 358

The number(s) below refer to the step number(s) on the diagnostic table.

1. 3. This test is to verify that the noise is being caused by the drive belt(s) or the accessory drive components. When removing the drive belt the water pump may not be operating and the engine may overheat. Also DTCs may set when the engine is operating with the drive belt removed.
2. 4. The inspection should include checking the drive belt tensioner and the drive belt idler pulley bearings. The drive belt(s) may have to be installed and the accessory drive components operated separately by varying their loads. Refer to the suspected accessory drive component for the proper inspection and replacement procedure.

Scheme 359

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2. This test is to verify that the symptom is present during diagnosing. Other vehicle components may cause a similar symptom.
2. 3. This test is to verify that the drive belt(s) is causing the rumbling noise. Rumbling noise may be confused with an internal engine noise due to the similarity in the description. Remove only one drive belt at a time if the vehicle has multiple drive belts. When removing the drive belt the water pump may not be operating and the engine may overheat. Also DTCs may set when the engine is operating with the drive belt removed.
3. 4. Inspecting the drive belt(s) is to ensure that it is not causing a the noise. Small cracks across the ribs of the drive belt will not cause the noise. Belt separation is identified by the plys of the belt separating and may be seen at the edge of the belt our felt as a lump in the belt.
4. 5. Small amounts of pilling is normal condition and acceptable. When the pilling is severe the drive belt does not have a smooth surface for proper operation.

Scheme 360

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2. This test is to verify that the symptom is present during diagnosing. Other vehicle components may cause a similar symptom such as the exhaust system, or the drivetrain.
2. 3. This test is to verify that the drive belt(s) or accessory drive components may be causing the vibration. When removing the drive belt the water pump may not be operating and the engine may overheat. Also DTCs may set when the engine is operating with the drive belt removed.
3. 4. The drive belt(s) may cause a vibration. While the drive belt(s) is removed this is the best time to inspect the condition of the belt.
4. 6. Inspecting of the fasteners can eliminate the possibility that a wrong bolt, nut, spacer, or washer was installed.
5. 8. This step should only be performed if the fan is driven by the drive belt. Inspect the engine cooling fan for bent, twisted, loose, or cracked blades. Inspect the fan clutch for smoothness, ease of turning. Inspect for a bent fan shaft or bent mounting flange.
6. 9. This step should only be performed if the water pump is driven by the drive belt. Inspect the water pump shaft for being bent. Also inspect the water pump bearings for smoothness and excessive play. Compare the water pump with a known good water pump.
7. 10. Accessory drive component brackets that are bent, cracked, or loose may put extra strain on that accessory component causing it to vibrate.

Scheme 361

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2. This inspection is to verify the condition of the drive belt. Damage may of occurred to the drive belt when the drive belt fell off. The drive belt may of been damaged, which caused the drive belt to fall off. Inspect the belt for cuts, tears, sections of ribs missing, or damaged belt plys.
2. 4. Misalignment of the pulleys may be caused from improper mounting of the accessory drive component, incorrect installation of the accessory drive component pulley, or the pulley bent inward or outward from a previous repair. Test for a misalign pulley using a straight edge in the pulley grooves across two or three pulleys. If a misalign pulley is found refer to that accessory drive component for the proper installation procedure of that pulley.
3. 5. Inspecting the pulleys for being bent should include inspecting for a dent or other damage to the pulleys that would prevent the drive belt from not seating properly in all of the pulley grooves or on the smooth surface of a pulley when the back side of the belt is used to drive the pulley.
4. 6. Accessory drive component brackets that are bent or cracked may will let the drive belt fall off.
5. 7. Inspecting of the fasteners can eliminate the possibility that a wrong bolt, nut, spacer, or washer was installed. Missing, loose, or the wrong fasteners may cause pulley misalignment from the bracket moving under load. Over tightening of the fasteners may cause misalignment of the accessory component bracket.

Scheme 362

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2. The inspection is to verify the drive belt(s) is correctly installed on all of the drive belt pulleys. Wear on the drive belt(s) may be caused by mis-positioning the drive belt(s) by one groove on a pulley.
2. 3. The installation of a drive belt that is two wide or two narrow will cause wear on the drive belt. The drive belt ribs should match all of the grooves on all of the pulleys.
3. 4. This inspection is to verify the drive belt(s) is not contacting any parts of the engine or body while the engine is operating. There should be sufficient clearance when the drive belt accessory drive components load varies. The drive belt(s) should not come in contact with an engine or a body component when snapping the throttle.

Scheme 363

Scheme 364

Note. Allowing the drive belt tensioner to snap into the free position may result in damage to the tensioner.

Important: When the engine is operating the drive belt tensioner arm will move. Do not replace the drive belt tensioner because of movement in the drive belt tensioner arm.

1. Remove the drive belt. Refer to «Drive Belt Replacement»(ref-245721-S33032740732006111600000) .
2. Position a 3/8 inch drive wrench on the drive belt tensioner arm and rotate the arm counterclockwise.
3. Move the drive belt tensioner through its full travel. The movement should feel smooth. There should be no binding. The tensioner should return freely.
4. If any binding is observed, replace the drive belt tensioner. Refer to «Drive Belt Tensioner Replacement»(ref-245721-S41144103472006111600000) .
5. Install the drive belt. Refer to «Drive Belt Replacement»(ref-245721-S33032740732006111600000) .

Scheme 365

1. Install a 3/8 inch drive wrench on the drive belt tensioner arm and rotate the arm counterclockwise.
2. Remove the drive belt.
3. Slowly release the tension on the drive belt tensioner arm.

Scheme 366

Scheme 367

Scheme 368

Scheme 369

Scheme 370

Scheme 371

Scheme 372

1. Route the drive belt over all the pulleys except the drive belt tensioner pulley.
2. Observe the drive belt routing for the vehicles without air conditioning.
3. Observe the drive belt routing for the vehicles with air conditioning.
4. Install a 3/8 inch drive wrench on the drive belt tensioner arm and rotate the arm counterclockwise.
5. Install the drive belt over the drive belt tensioner pulley.
6. Slowly release the tension on the drive belt tensioner arm.
7. Inspect for the drive belt being properly installed on the pulleys.
8. Avoid mis-positioning the drive belt by one or more grooves.
9. Confirm for the proper drive belt size and the correct drive belt routing by observing the location of the fix pointer and the index marks on the drive belt tensioner. With a new drive belt installed the fix pointer should align within the indentation on the drive belt tensioner.
10. With a used drive belt installed the fix pointer should not align past the index mark.

Scheme 373

1. Remove the drive belt. Refer to «Drive Belt Replacement»(ref-245721-S33032740732006111600000) .
2. Remove the bolt.
3. Remove the drive belt tensioner.

Scheme 374

1. Install the drive belt tensioner assembly.
2. Install the attaching bolt. Tighten Tighten the tensioner assembly bolt to 50 N.m (37 lb ft).
3. Install the drive belt. Refer to «Drive Belt Replacement»(ref-245721-S33032740732006111600000) .

Scheme 375

1. Remove the drive belt. Refer to «Drive Belt Replacement»(ref-245721-S33032740732006111600000) .
2. Remove the drive belt idler pulley bolt.
3. Remove the drive belt idler pulley.

Scheme 376

1. Install the drive belt idler pulley and bolt to the generator mounting bracket. Tighten Tighten the bolt to 50 N.m (37 lb ft).
2. Install the drive belt. Refer to «Drive Belt Replacement»(ref-245721-S33032740732006111600000) .

Scheme 377

1. Remove the drive belt. Refer to «Drive Belt Replacement»(ref-245721-S33032740732006111600000) .
2. Remove the belt idler pulley bolt.
3. Remove the belt idler pulley from the power steering pump mounting bracket.

Scheme 378

1. Install the belt idler pulley and the bolt to the power steering pump mounting bracket. Tighten Tighten the bolt to 50 N.m (37 lb ft).
2. Install the drive belt. Refer to «Drive Belt Replacement»(ref-245721-S33032740732006111600000) .

Scheme 379

1. Raise the vehicle.
2. Inspect for loose or missing bolts at the following locations: The engine mount to the engine The engine mount to the engine mount frame bracket through-bolts The engine mount frame bracket to the frame
3. Replace missing or loose bolts. Refer to «Engine Mount Replacement - Left»(ref-245721-S17172075502006111600000) or «Engine Mount Replacement - Right»(ref-245721-S03413530602006111600000) .
4. In order to access the square tab on the right side of the engine remove the starter. Refer to appropriate STARTER article. Using a jack on the square tab at the rear of the engine block (left side shown the right side requires removal of the starter) raise the engine in order to complete the following tasks: Remove weight from the engine mount. Place a slight tension on the rubber cushion. Observe the engine mount while raising the engine.
5. Replace the engine mount if the following conditions exist: Heat check cracks cover the hard rubber surface. The rubber cushion is separated from the metal plate of the engine mount. There is a split through the rubber cushion. Replace the starter, if removed. Refer to appropriate STARTER article.
6. Lower the vehicle.

Drive Belt System Description

The drive belt system consists of the following components

1. The drive belt
2. The drive belt tensioner
3. The drive belt idler pulley
4. The crankshaft balancer pulley
5. The accessory drive component mounting brackets
6. The accessory drive components The power steering pump, if belt driven The generator The A/C compressor, if equipped The engine cooling fan, if belt driven The water pump, if belt driven The vacuum pump, if equipped The air compressor, if equipped

The drive belt system may use one belt or two belts. The drive belt is thin so that it can bend backwards and has several ribs to match the grooves in the pulleys. There also may be a V-belt style belt used to drive certain accessory drive components. The drive belts are made of different types of rubbers (chloroprene or EPDM) and have different layers or plys containing either fiber cloth or cords for reinforcement.

Both sides of the drive belt may be used to drive the different accessory drive components. When the back side of the drive belt is used to drive a pulley, the pulley is smooth.

The drive belt is pulled by the crankshaft balancer pulley across the accessory drive component pulleys. The spring loaded drive belt tensioner keeps constant tension on the drive belt to prevent the drive belt from slipping. The drive belt tensioner arm will move when loads are applied to the drive belt by the accessory drive components and the crankshaft.

The drive belt system may have an idler pulley, which is used to add wrap to the adjacent pulleys. Some systems use an idler pulley in place of an accessory drive component when the vehicle is not equipped with the accessory.