Known faults for the BMW Serie 3 (E46).

Engine / equipment

M52TU and M54 six-cylinder petrol (320i–330i E46, 520i–530i E39, 520i–530i E60 up to 2005, X3 2.5i/3.0i, X5 3.0i, six-cylinder Z3 and Z4)

Period mentioned

1998–2006

Symptoms

Coolant loss without an obvious puddle, sweet smell, low-level warning, steam in the engine bay, heater stops warming and the temperature needle rises. Expansion tank failure is usually sudden; the water pump can fail with no visible leak.

Possible cause described

Many cooling parts are plastic and become brittle with heat and age: expansion tank, radiator neck, thermostat housing and the water pump impeller, which can crack or come off its shaft and stop pumping. The electric auxiliary pump is also a frequent failure.

Check for the garage

With the engine cold, check the level and look for cracks or dried coolant on the tank, radiator neck and thermostat housing. At a garage: pressure-test the system and inspect the pump. If the temperature rises, stop somewhere safe: a single overheat can warp the aluminium head. Never open the system hot.

Cost cited in the source

No verifiable estimate in the sources; ask for a quote. The sources recommend replacing tank, pump (preferably with a metal impeller), thermostat and hoses together on high-mileage engines.A rough figure from the original database, not an up-to-date quote.

Sources from the original database

Engine / equipment

M52TU and M54 six-cylinder petrol (320i–330i E46, 520i–530i E39, 520i–530i E60 up to 2005, X3 2.5i/3.0i, X5 3.0i, six-cylinder Z3 and Z4)

Period mentioned

1998–2006

Symptoms

High oil consumption, bluish smoke, rough idle, whistling from a vacuum leak, engine light with lean-mixture codes and very strong suction when trying to remove the oil filler cap at idle.

Possible cause described

The system has a regulating valve and four plastic and rubber hoses under the intake manifold. The valve membrane tears and the hoses crack; on short trips in cold weather, condensation mixes with the oil, blocks the return through the dipstick tube and can freeze. Several forum owners cut oil consumption sharply by renewing the system, though others also blame piston ring wear.

Check for the garage

At a garage: smoke-test the intake to find leaks (CCV hoses, intake boots, DISA valve seal, valve cover gasket) and check whether the dipstick tube return is blocked. A cold-climate version of the system exists for cold regions.

Cost cited in the source

No verifiable estimate in the sources; ask for a quote. It is labour-intensive because the intake has to be removed.A rough figure from the original database, not an up-to-date quote.

Sources from the original database

Engine / equipment

M52TU and M54 six-cylinder petrol with double VANOS (320i–330i E46, 520i–530i E39, 520i–530i E60 up to 2005, X3 2.5i/3.0i, X5 3.0i, six-cylinder Z3 and Z4)

Period mentioned

1998–2006

Symptoms

Loss of torque and pull below about 3,000 rpm, louder or unsteady idle, the engine bogs when the air conditioning is switched on and sometimes VANOS fault codes. On 1998–2000 M52TU engines, jolts or stalling on cold starts.

Possible cause described

VANOS varies intake and exhaust timing with two hydraulic pistons. The O-rings on those pistons lose elasticity and flatten, oil leaks past them and the system cannot reach the requested position. According to the repair-kit maker, remanufactured units use the same original seals.

Check for the garage

Read the engine codes and, at a garage, compare actual and requested camshaft positions in live data. Rule out vacuum leaks and the CCV first, as they cause similar symptoms. On M52TU engines with cold jolts, the kit maker describes a test with the intake VANOS solenoid unplugged.

Cost cited in the source

Seal kit: about $60 in parts according to its maker (US price), plus gasket and washers; labour extra.A rough figure from the original database, not an up-to-date quote.

Sources from the original database

Engine / equipment

BMW 3 Series E46 (petrol and diesel)

Period mentioned

1998–2007

Symptoms

On cars built up to March 2000, the rear axle mounting can tear out of the body; worn wishbone bushes (noises and a nervous wheel under braking) and broken rear springs; hairline cracks in the expansion tank; oil pump on the six-cylinders; camshaft sensors, turbos and injection pumps; swirl flaps dropping into the cylinder on diesels; weak handbrake and porous brake pipes.

Possible cause described

At first BMW repaired the axle mounting with special foam or new floor panels as goodwill; today the repair is so expensive that it often is not worth it. Recalls: a passenger airbag that could burst (saloons May 1999 to August 2006) and gas generators in the sports steering wheel (November 1997–June 2000).

Check for the garage

On cars up to 2000, inspect the rear axle mounting area on a lift; check airbag campaigns by VIN.

Cost cited in the source

No verified estimate; ask the garage for a quote.A rough figure from the original database, not an up-to-date quote.

Sources from the original database

Engine / equipment

M47TU 2.0 diesel with swirl flaps (318d/320d E46 from 2001, 118d/120d E87, 320d E90 and 520d E60 until 2007, X3 2.0d)

Period mentioned

2001–2007

Symptoms

Loss of power, smoke or knocking, often with no prior warning: one of the flaps comes loose and drops into the cylinder.

Possible cause described

The small swirl flaps in the intake manifold work loose with vibration and can break off into the cylinder, damaging the piston, valves and turbo. BMW strengthened the flaps in 2006.

Check for the garage

Check whether they have already been removed or replaced with blanking plugs and inspect the intake manifold.

Cost cited in the source

€4,000–6,000 if the failure damages the engine; prevention costs far lessA rough figure from the original database, not an up-to-date quote.

Sources from the original database

Engine / equipment

M57 3.0 six-cylinder diesel with swirl flaps (330d E46/E90, 525d/530d/535d E39/E60, 635d, 730d E65, X3 3.0d, X5 3.0d E53/E70, X6 30d/35d)

Period mentioned

1998–2010

Symptoms

Usually none until it fails. A common early warning: oil seeping around the flap spindles on top of the engine. If a flap or its screw comes loose and enters a cylinder: sudden heavy knocking, loss of power, smoke and possible turbo damage as well.

Possible cause described

The metal flaps in the intake manifold collect soot and oil and their spindles wear over the years. The flap, its screw or part of the spindle can come loose and drop into the cylinder, damaging valves, piston and head. An owners' forum quotes BMW as having strengthened the spindles on later manifolds (from 4 to 4.5 mm), but other owners doubt the change removes the risk.

Check for the garage

At a garage: confirm whether the manifold has swirl flaps (some versions do not), look for oil around the spindles and play in the flaps, and check the history for earlier replacement or removal. With any new metallic knocking, stop the engine and do not restart it.

Cost cited in the source

Preventive inspection: workshop labour. If a flap enters the engine, a buyer's report quotes repair costs above €4,000.A rough figure from the original database, not an up-to-date quote.

Sources from the original database

Engine / equipment

S54 (M3 E46, Z4 M), S65 V8 (M3 E90/E92/E93) and S85 V10 (M5 E60, M6 E63)

Period mentioned

2000–2013

Symptoms

Little prior warning; once wear is advanced, a metallic rod knock that rises with revs. On the S65 and S85, also jerking and limp mode from failing throttle actuators.

Possible cause described

Very tight rod bearing clearances and soft bearing material, made worse by cold oil, revving the engine before it is warm and poor maintenance. Catastrophic failure is rare, but premature wear is common.

Check for the garage

Oil analysis and bearing replacement history. Indicative preventive replacement: S54 around 130,000–160,000 km, S65 around 100,000–130,000 km and S85 around 80,000–110,000 km.

Cost cited in the source

Preventive replacement: approx. €2,800–5,500 (converted from dollars); a spun bearing costs far moreA rough figure from the original database, not an up-to-date quote.

Mileage cited in the database: 80,000–160,000 km. This is not a maintenance interval and does not predict a failure.

Sources from the original database