Engine fault diagnostics (Peugeot 305)

A faulty fuel injection system can cause noises typical of failed bearings. In order to identify the cause of the noise, you should loosen the injector fittings one by one while the engine is running. The noise should disappear when the fitting on the faulty injector is loosened, however, to be completely sure that the injector is faulty, you should move it to another cylinder and repeat the tests again. Engine knocking can also be caused by the presence of air or dirt in the fuel.

The engine does not turn over with the starter

• The battery is dead
• The contacts on the battery terminals have become loose or corroded
• The contacts on the starter solenoid terminals have become loose
• The engine/gearbox ground wire is loose or damaged
• Starter faulty

The engine turns over normally, but does not start

• The startup procedure was performed incorrectly
• The fuel injection pump shut-off solenoid is faulty or there is a break in its wiring
• The fuel contains resins and paraffin (appears only in very cold weather)
• The timing belt broke. Fuel system malfunction
• Poor compression (see below)
• The synchronization of the fuel injection pump is disrupted

Rough idle

• Fuel system malfunction
• Incorrectly adjusted valve clearances
• The valves are burnt
• The cylinder head gasket is blown

Poor compression

• The valves are burnt
• Valve clearances too small
• The cylinder head gasket is blown
• Worn piston rings/cylinders
• Cracks in the cylinder head or block

The engine does not develop the required power

• Poor compression (see above)
• The synchronization of the fuel injection pump is disrupted
• The injectors are worn out or dirty
• The air filter is clogged

Excessive oil consumption

• The camshaft or crankshaft seals are leaking
• Worn piston rings/cylinders (a sign is smoky exhaust)
• External oil leaks

Unusual noises when the engine is running

• Peripheral equipment failure (for example, a water pump or a generator)
• The timing belt or alternator drive belt is worn or damaged
• Broken piston ring(s)
• The connecting rod bearings are worn out (noise increases without load)
• The main bearings are worn out (noise increases under load)
• Injector or fuel injection pump malfunction (see chapter 3)

Smoky exhaust

• The engine burns oil (the exhaust has a blue tint)
• Fuel system malfunction

[Source of the article is website: peugeotbook.ru]