Noise and Knock Troubleshooting

GENERAL INFORMATION.

Excessive Valve Train Noise

– Low oil pressure. Perform the necessary repair.

– Loose parts driven by the camshaft. Check and eliminate the fault.

– Wear of parts driven by the camshaft.

– Broken valve spring.

– Valve stem seizure.

– Wear, contamination or malfunction of the valve train. Check and clean the parts, replace them if necessary.

– Worn or poorly machined camshaft. Replace the camshaft.

– Worn valve guides.

Knocking on a cold engine heard for 2-3 minutes after starting, knocking

increases with increasing torque, is considered normal.

– Vacuum-operated EFE valve knock. Replace the EFE valve.

– Flywheel contacts the housing. Correct the position of the housing.

– Loose vibration damper or pulley mounting. Tighten the mounting or replace if necessary.

– Increased clearance between pistons and cylinders. Replace the pistons. Piston knock on a cold engine usually disappears after grounding the spark plug of the corresponding cylinder. Piston knock on a cold engine that disappears within about 1.5 minutes after starting is considered normal.

– Bent connecting rod.

Heavy Knocking on a Warm Engine Under Increased Torque

– Broken vibration damper or pulley hub. Replace the faulty parts.

– Loose torque converter mounting bolts.

– Overtightened auxiliary drive belts or cracked belts.

Adjust the belt tension or replace the faulty belts.

– Exhaust system components contacting the underbody. If necessary, restore the correct position of the exhaust system components.

– Crack in the flywheel.

– Increased clearance in main bearings. Replace the bearing shells as necessary.

– Increased clearance in connecting rod bearings. Replace the bearing shells as necessary.

Light Knocking on a Warm Engine

– Detonation. Check the electronic ignition timing control. Check the ignition timing and fuel quality.

– Loose torque converter mounting bolts.

– Leaks at the exhaust system joints. Tighten the bolts and/or replace the gasket.

– Increased clearance in connecting rod bearings. Replace the bearing shells as necessary.

Short knocking immediately after engine start-up.

– Mechanical noise from fuel pump. Replace pump.

– Use of non-recommended engine oil. Replace oil. Use

engine oil with a viscosity corresponding to the prevailing

vehicle operating conditions (ambient temperature range).

– Faulty hydraulic valve lifters. Clean, check and replace.

as necessary. When the engine is stopped, some valves remain open and

under the action of the valve spring, oil is forced out of the lifters. Replace

lifters only if a malfunction is found.

– Excessive crankshaft end play. Replace crankshaft thrust bearing.

– Excessive clearance in front main bearing. Replace worn parts.

Knocking with warm engine running at idle.

– Loose or worn drive belts. Adjust tension or replace as necessary.

– Worn air conditioning compressor or alternator bearings. Replace faulty

bearings.

– Mechanical noise from fuel pump. Replace pump.

– Noise from valve train components. Replace faulty parts.

– Use of non-recommended engine oil. Replace oil. Use

engine oil with a viscosity corresponding to the prevailing

vehicle operating conditions.

– Excessive clearance between piston pins and pistons. Replace pistons and pins.

– Misalignment of connecting rod small end bores. Inspect connecting rods and replace.

faulty parts.

– Insufficient clearance between pistons and cylinders. Hone cylinders and

install a set of new pistons.

– Loose vibration damper mounting. Tighten mounting or replace.

worn parts.

– Incorrect piston pin offset. Reinstall piston.