Definition for Knock
Engine knock refers to various types of engine noise. Heavy knock is usually very loud and the result of broken or excessively worn internal engine components. Light knock is a noticeable noise, but not as loud. Light knock can be caused by worn internal engine components. Loose or broken external engine components can also cause heavy or light knock.
Light Knock Hot
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Is there a light knock when the engine is hot? | Go to Step 2 | System OK | |
| 2 | Is detonation or spark knock evident? | Go to Step 3 | Go to Step 4 | |
| 3 | Check the engine timing and the fuel quality. Was the problem found? | Go to Step 1 | ||
| 4 | Inspect the torque converter bolts. Are the bolts tightened to the specified value? | 45 N.m (33 lb-ft) | Go to Step 5 | Go to Step 6 |
| 5 | Tighten the torque converter bolts. Is the repair complete? | Go to Step 1 | ||
| 6 | Inspect the manifold. Is there an exhaust leak at the manifold? | Go to Step 7 | Go to Step 8 | |
| 7 | Tighten the bolts or replace the gasket. Is the repair complete? | Go to Step 1 | ||
| 8 | Check the rod bearing clearance. Is the clearance within the specified value? | 0.019 - 0.070 mm (0.0007 - 0.0028 in.) | Go to Step 9 | System OK |
| 9 | Replace the rod bearings, as necessary. Is the repair complete? | Go to Step 1 |
LIGHT KNOCK HOT REFERENCE CHART
Knocks During Initial Start-Up But Last Only a Few Seconds
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Does the engine knock during initial startup but last only a few seconds? | Go to Step 2 | System OK | |
| 2 | Check the engine oil. Is the proper viscosity oil used in the crankcase? | Go to Step 4 | Go to Step 3 | |
| 3 | Install oil of the proper viscosity for the expected seasonal temperatures. Is the repair complete? | Go to Step 1 | ||
| 4 | Inspect the hydraulic lifters. Is there evidence of hydraulic lifter bleed-down? | Go to Step 5 | Go to Step 6 | |
| 5 | Clean, test and replace the lifters, as necessary. Is the repair complete? (1) | Go to Step 1 | ||
| 6 | Inspect the crankshaft end clearance. Is the clearance more than specified value? | 0.070 - 0.302 mm (0.0027 - 0.0118 in.) | Go to Step 7 | Go to Step 8 |
| 7 | Replace the crankshaft thrust bearing. Is the repair complete? | Go to Step 1 | ||
| 8 | Inspect the front main bearing clearance. Is the clearance more than the specified value? | 0.015 - 0.040 mm (0.00059 - 0.00157 in.) | Go to Step 9 | System OK |
| 9 | Replace the worn parts of the front main bearing. Is the repair complete? | Go to Step 1 | ||
| (1) When the engine is stopped, some valves will be open. Spring pressure against the lifters will tend to bleed lifter down. Attempts to repair this should be made only if the problem is consistent. | ||||
| (1) | When the engine is stopped, some valves will be open. Spring pressure against the lifters will tend to bleed lifter down. Attempts to repair this should be made only if the problem is consistent. |
KNOCKS DURING INITIAL START-UP BUT LAST ONLY A FEW SECONDS REFERENCE CHART
An engine that is only operated for short periods between start-ups may have lifter noise that lasts for a few minutes. This is a normal condition.
Knocks at Idle Hot
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Does the engine knock at idle when hot? | Go to Step 2 | System OK | |
| 2 | Inspect the drive belts. Are the belts loose or worn? | Go to Step 3 | Go to Step 4 | |
| 3 | Tension or replace the belts, as necessary. Is the repair complete? | Go to Step 1 | ||
| 4 | Inspect the A/C compressor and the generator. Is either the compressor or the generator faulty? | Go to Step 5 | Go to Step 6 | |
| 5 | Replace the faulty A/C compressor or the generator. Is the repair complete? | Go to Step 1 | ||
| 6 | Inspect the valve train. Are valve train components faulty? | Go to Step 7 | Go to Step 8 | |
| 7 | Replace the faulty valve train components. Is the repair complete? | Go to Step 1 | ||
| 8 | Check the engine oil. Is the proper viscosity oil used in the crankcase? | Go to Step 10 | Go to Step 9 | |
| 9 | Install oil of the proper viscosity for the expected seasonal temperatures. Is the repair complete? | Go to Step 1 | ||
| 10 | Inspect the piston pin clearance. Is the clearance more than the specified value? | 0.0035 - 0.0140 mm (0.00013 - 0.00055 in.) | Go to Step 11 | Go to Step 12 |
| 11 | Replace the piston and the pin. Is the repair complete? | Go to Step 1 | ||
| 12 | Check the connecting rod alignment. Is the alignment faulty? | Go to Step 13 | Go to Step 14 | |
| 13 | Check and replace rods, as necessary. Is the repair complete? | Go to Step 1 | ||
| 14 | Inspect the piston-to-bore clearance. Is the clearance within the specified value? | 0.010 - 0.030 mm (0.00039 - 0.00111 in.) | Go to Step 16 | Go to Step 15 |
| 15 | Hone the bore and fit a new piston. Is the repair complete? | Go to Step 1 | ||
| 16 | Inspect the crankshaft balancer. Is the balancer loose? | Go to Step 17 | Go to Step 18 | |
| 17 | Torque or replace worn parts. Is the repair complete? | Go to Step 1 | ||
| 18 | Check the piston pin offset. Is the offset at the specified value? | 1.0 mm (0.04 in.) Toward Thrust Side | Go to Step 19 | System OK |
| 19 | Install the correct piston. Is the repair complete? | Go to Step 1 |
KNOCKS AT IDLE HOT REFERENCE
Piston Noises
| Step | Action | Value (s) | Yes | No |
|---|---|---|---|---|
| 1 | Are any of the following noises heard: a sharp double knock when the engine is idling, a light ticking with no load on the engine, or a "slapping" noise when the engine is cold? | Go to Step 2 | System OK | |
| 2 | Inspect the piston pin and the bushing. Is the piston pin or the bushing worn or loose? | Go to Pistons and Rods Removal and Installation . | Go to Step 3 | |
| 3 | Inspect the piston. Is the piston broken or cracked? | Go to Pistons and Rods Removal and Installation . | Go to Step 4 | |
| 4 | Inspect the connecting rods. Is there a misaligned connecting rod? | Go to Pistons and Rods Removal and Installation . | Go to Step 5 | |
| 5 | Inspect the piston position. Is the piston 180° out of position? | Go to Pistons and Rods Removal and Installation . | System OK |
PISTON NOISES REFERENCE CHART
Valve Mechanism or Valve Train Noises
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Is a light tapping sound heard from the engine? | Go to Step 2 | System OK | |
| 2 | Inspect the valve springs. Are the springs weak or broken? | Go to Cylinder Head and Valve Train Components Disassembly and Assembly . | Go to Step 3 | |
| 3 | Inspect the valves. Are the valves sticking or warped? | Go to Cylinder Head and Valve Train Components Disassembly and Assembly . | Go to Step 4 | |
| 4 | Inspect the valve lifters. Are the valve lifters dirty, stuck or worn? | Go to Cylinder Head and Valve Train Components Disassembly and Assembly . | Go to Step 5 | |
| 5 | Inspect the camshaft lobes. Are the camshaft lobes damaged or improperly machined? | Go to Cylinder Head and Valve Train Components Disassembly and Assembly . | Go to Step 6 | |
| 6 | Check the oil supply to the valve train. Is the oil supply insufficient or poor? | Go to Cylinder Head and Valve Train Components Disassembly and Assembly . | Go to Step 7 | |
| 7 | Inspect the valve guides. Are the valve guides worn? | Go to Cylinder Head and Valve Train Components Disassembly and Assembly . | Go to Step 8 | |
| 8 | Inspect the valve spring seat. Is the valve spring seat incorrect? | Go to Cylinder Head and Valve Train Components Disassembly and Assembly . | System OK |
VALVE MECHANISM OR VALVE TRAIN NOISES
Scheme 102
Scheme 103
Scheme 104
- Disconnect the negative battery cable.
- Disconnect the breather tube from the valve cover.
- Disconnect all of the necessary vacuum lines.
- Remove the spark plug cover bolts.
- Remove the spark plug cover.
- Disconnect the ignition wires from the spark plugs.
- Disconnect the camshaft position sensor connector.
- Remove the camshaft cover bolts.
- Remove the camshaft cover.
- Remove the camshaft cover gasket from the camshaft cover.
Scheme 105
Scheme 106
- Apply a small amount of gasket sealant to the corners of the front camshaft caps and the top of the rear camshaft cover-to-cylinder head seal.
- Install the new camshaft cover gasket to the camshaft cover.
- Install the camshaft cover.
- Install the camshaft cover bolts. Tighten: Tighten the camshaft cover bolts to 8 N.m (71 lb-in).
- Connect the ignition wires to the spark plugs.
- Install the spark plug cover. Tighten: Tighten the spark plug cover bolts to 8 N.m (71 lb-in).
- Install the spark plug cover bolts.
- Connect the camshaft position sensor connector.
- Connect all of the necessary vacuum lines.
- Connect the breather tube to the camshaft cover.
- Connect the negative battery cable.