E30 3-Series

1982-1994 / Sedan / Convertible / Estate / Germany

All E30 3-Series problems All workshop issues

Minor Engine, M20 (320i, 323i, 325i, 325e)

Timing Belt Failure

Symptoms

The engine stops instantly while driving. If the belt snaps at speed, the valves collide with the pistons, destroying the cylinder head and potentially the pistons as well. The engine is scrap without a full rebuild.

Cause

The M20 has an unusual design, a timing chain drives the camshaft from the front, while a separate timing belt at the rear of the engine drives the intermediate (auxiliary) shaft. This belt is made of rubber and degrades with age and heat regardless of mileage. The belt is hidden at the back of the engine, against the firewall, so it's out of sight and out of mind. Many owners forget about it until it's too late.

Fix

Replace the timing belt, tensioner, and water pump every 60,000-80,000 km or every 4 years, whichever comes first.

The job requires removing the intake manifold and various components to access the rear of the engine.

It's a 4-6 hour job for an experienced mechanic.

Cost: $400-700 at a specialist.

DIY cost: $80-150 in parts.

Cost mentioned in fix

Cost: $400-700cost: $80-150 in parts

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// More E30 3-Series problems

Other known issues

Critical Engine, M20 (320i, 323i, 325i, 325e)

Head Gasket Failure

Coolant loss without visible external leak. White smoke from the exhaust (coolant burning in the combustion chamber). Overheating. Milky emulsion under the oil filler cap. Coolant in the oil (oil level rises, oil appears grey or milky on the dipstick). Bubbles in the expansion tank with the engine running.

Critical Engine, M20 (320i, 323i, 325i, 325e)

Oil Leaks, Everywhere

Oil weeping from the valve cover gasket, oil filter housing gasket, oil pan gasket, rear main seal, and front crank seal. A high-mileage M20 will have oil residue on virtually every surface.

Common Engine, M20 (320i, 323i, 325i, 325e)

Idle Control Valve (ICV) Failure

Rough idle, idle speed hunting (revs surging up and down between 500 and 1,500 rpm), stalling when coming to a stop, or idle sitting too high (1,200+ rpm). The engine may idle fine when cold but develop problems as it warms up.

Critical Engine, M40 (318i, late model)

Timing Belt and Chain Issues

Rattling noise on cold start from the front of the engine (chain). Engine misfiring or loss of power (belt).

Common Engine, M40 (318i, late model)

Crankcase Ventilation (CCV) Failure

Oil consumption increases, rough idle, oil leaks, whistling noise from the engine, check engine light.

Critical Cooling System (All Models)

Expansion Tank Cracking

Coolant leak from the expansion tank, often sudden and catastrophic. The tank may crack along a seam or at the neck where the cap sits. Coolant pours out, the engine overheats within minutes.

View all 20 E30 3-Series problems