E36 3-Series

1990-2000 / Sedan / Coupe / Convertible / Estate / Germany

All E36 3-Series problems All workshop issues

Critical Engine, M50/M52 (320i, 325i, 328i)

Cooling System Failure, Water Pump

Symptoms

Engine temperature gradually rises above normal, or suddenly overheats. Coolant leak from the water pump area. In some cases, no external symptoms, the plastic impeller simply disintegrates inside the pump housing, and broken plastic fragments circulate through the cooling system, blocking the heater core and radiator passages.

Cause

The factory water pump uses a plastic impeller mounted on a metal shaft. The plastic degrades from coolant exposure and heat, and the impeller vanes crack or separate entirely from the hub. The bearing also wears, allowing the shaft to wobble and the seal to leak.

Fix

Replace with a metal-impeller water pump.

The Stewart Components pump and the Graf metal-impeller pump are the most recommended.

Always replace the thermostat and coolant at the same time.

If the old pump's impeller was broken, flush the cooling system thoroughly to remove plastic fragments.

Cost: $120-250 for a quality pump.

Cost mentioned in fix

Cost: $120-250 for a

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Other known issues

Common Engine, M50/M52 (320i, 325i, 328i)

VANOS Seal Failure

Rattling or clattering noise from the front of the engine on cold start, lasting 10-30 seconds before fading as oil pressure builds. Loss of low-end torque, the engine feels flat below 3,000 rpm and only comes alive higher in the rev range. In severe cases, rough idle and a general feeling that the engine is "lazy" at low speeds.

Critical Engine, M50/M52 (320i, 325i, 328i)

Cooling System Failure, Expansion Tank

The plastic expansion tank cracks, often along a moulding seam or at the neck where the cap seals. Coolant pours out rapidly. The engine overheats within minutes if the driver doesn't notice the temperature gauge climbing.

Common Engine, M50/M52 (320i, 325i, 328i)

Cooling System Failure, Thermostat Housing

Coolant leak from the thermostat housing area. The leak may be slow (seeping at the gasket) or sudden (the plastic housing cracks).

Critical Engine, M50/M52 (320i, 325i, 328i)

Oil Leaks

Oil weeping or dripping from the valve cover gasket, oil filter housing gasket, oil pan gasket, VANOS oil line seals, and front crank seal. A high-mileage M50 or M52 will have oil residue on most external surfaces.

Common Engine, M50/M52 (320i, 325i, 328i)

M52 Nikasil Bore Wear (Early M52 Only)

Difficult cold starting, rough running, misfiring, loss of compression. Cylinder leak-down test shows excessive leakage past the piston rings.

Common Engine, S50 (M3)

VANOS Failure (Single and Double VANOS)

Same symptoms as the M50/M52 VANOS failure, cold-start rattle, loss of low-end torque, but more pronounced on the M3. The S50B32 (3.2L) uses double-VANOS (variable timing on both intake and exhaust cams), which doubles the number of seals that can fail.

View all 18 E36 3-Series problems