Known faults for the BMW Z4 (E85/E86).

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

ZF 6-speed automatic 6HP19/21/26/28 (E53, E60/E61, E63/E64, E65/E66, E85, E90–E93)

Period mentioned

Approx. 2001–2013

Symptoms

Oil drips or dampness by the electrical connector on the side of the pan, a bump on the downshift just before stopping, harsh or flared shifts (especially 3rd-4th and 4th-5th under throttle) and a limp mode that clears after restarting.

Possible cause described

The sealing sleeve between the mechatronic unit and the wiring harness has O-rings that harden and let oil out. A BMW bulletin says to replace it only for a real leak, not mere dampness, and warns that fitting it wrongly damages the connector pins and forces a mechatronic replacement. With low fluid the gearbox loses pressure. Harsh shifts can also come from worn solenoids or valve body, not only the sleeve.

Check for the garage

At a garage: read the gearbox codes, check the fluid level with the official procedure (correct temperature and engine running) and look for a real leak at the sleeve and pan gasket. After a fluid or parts change, the garage should reset adaptations. If limp mode persists, check solenoids and valve body before replacing the gearbox.

Cost cited in the source

Sleeve and pan gasket: minor repair. If fluid is lost and the gearbox is damaged, in a US forum case BMW offered a remanufactured gearbox for about $2,800 without fitting.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