Skip to content
MOTRS

E30 3-Series

1982-1994 / Sedan / Convertible / Estate / Germany

All E30 3-Series problems All workshop issues
Critical Engine, M40 (318i, late model)

Timing Belt and Chain Issues

Symptoms

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

Cause

The M40, like the M20, has both a timing chain and a timing belt. The chain tensioner weakens with age, allowing the chain to slap against its guides. The timing belt at the rear degrades with age. If the chain jumps a tooth, valve timing shifts and the engine runs poorly. If the belt snaps, it's catastrophic.

Fix

Replace the timing belt every 60,000 km.

If the chain is rattling, replace the chain, tensioner, and guides, this requires front cover removal.

Cost: $300-600 for belt service, $500-900 for chain service.

Cost mentioned in fix
Cost: $300-600 for belt$500-900 for chain

Know something we don't?

Owned a BMW E30 3-Series? Share your experience with this issue. What worked, what didn't, costs, tips. Help the community.

Submit an update
// More E30 3-Series problems

Other known issues

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

Timing Belt Failure

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.
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 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