This article is devoted exclusively to the problems associated with the BMW E46, and to be more correct, the problems that you MAY encounter immediately after purchase or during the operation of the car and should not be considered as an indicator of the reliability of the model or its safety in general. Possible malfunctions that the manufacturer has officially recognized will also be indicated. Separately, I would like to note a critical point that everyone knows. Still, some of us do not consider when a breakdown occurs – the reliability of the car depends on the amount of your attention to it, and attention is a dish of two ingredients – national/foreign currency and a pinch of quality, which concerns the second. The machine will thank you for a long time.

As you know, BMW 3 E46 is not a new car, and the manufacturer’s warranty was “dusty” a long time ago; therefore, if you are considering buying a vehicle, weigh all the pros and cons and everything that comes to your eyes and mind – we also recommend weighing it, since it has long been a used car. You might expect problems from everything installed in it, especially if the vehicle before you was in the hands of a “rider”. We also note that the issues do not apply to each car since breakdowns are individual issues.

If you are the owner of this great car, this article will instead become for you a simple informational material about your vehicle, which may come in handy someday. Of course, it is not possible to put everything in the article, so if something is missed, we will be very grateful for your addition, which you have the opportunity to leave in the comments, for which we will be very, very, very thankful to you 🙂

Engine

On M52 and M54 engines equipped with VANOS ( 320i, 325i, 328i and 330i ), wear will cause the VANOS piston seal O-rings made from Buna (material with limited heat resistance) to fail due to wear. Over time, O-rings harden and shrink, resulting in a loss of functionality – this can lead to symptoms such as loss of power below 3000 rpm, rpm increase to around 3000 rpm, louder idle and rough operation.

Piston O-rings are located under the Teflon piston O-ring and provide support for the piston. Replacing O-rings requires Teflon seals for access. Since the Teflon seals cannot be removed from the piston seal groove without damaging the piston, the Teflon and O-rings must be replaced simultaneously. Buna O-rings can be replaced with Viton O-rings to increase service life.

See our used BMW E46 Engines For Sale

The VANOS unit has two O-ring piston seals. In contrast, each piston has two O-ring sizes for a hydraulic seal in two different VANOS cylinders of various sizes. An additional smaller O-ring was used to seal the piston bearing. The o-ring for this cap was also made from Buna and was worn the same way as the piston seal o-rings. It is possible to solve the problem by purchasing a VANOS repair kit and replacing the rings.

Oil filter housing gasket

As with many engine soft gaskets, the oil filter housing gasket (11421719855) is standard. This gasket hardens over time due to heat cycles from the engine and oil contamination, resulting in oil leakage. If the oil is on the driver’s side, on the cylinder block next to the oil filter, it is the gasket leaking.

Depending on the amount of leakage, this can also cause the low oil level light on the instrument panel to come on. There have been cases where oil leaks caused the belt to slip and get stuck in the primary seal behind the crankshaft pulley. Deposits in the injection system Separately, the BMW 320i, 325i and 330i equipped with the M54 engine is worth noting. In these vehicles, deposits in the injection and induction systems can cause the engine to run unstable by issuing a “Service Engine Soon” warning.

This problem can be caused by: deposits on the tip of the fuel injector that affect fuel consumption and air/fuel ratio. Symptoms: rpm fluctuation during acceleration or loss of power, low fuel efficiency, increased HC and CO emissions, “Service Engine Soon” indicator comes on due to misfiring; Carbon deposits on the valves and intake manifold ports that absorb fuel during the warm-up phase result in a thinner air/fuel mixture. Carbon deposits (or build-up) can also interfere with the flow of the mixture at idle.

Symptoms: loss of power, unstable and rough idling, increased HC, CO and NOx emissions, “Service Engine Soon” lamp comes on due to intermittent misfire failures;

Cold climate

Frigid climates in BMW E46 320i, 325i and 330i with the M54 engine can cause moisture to build up and freeze in: in the engine oil separator; hose to the dipstick guide pipe; holes in the probe guide tube;

Depending on the position of the crankcase ventilation valve, the following can occur when this problem occurs: valve cover leaking due to high pressure in the crankcase; damage to the engine due to hydraulic blocking of oil (stuck in the open position);

The problem can be solved by replacing the crankcase breather valve, the crankcase breather hose and the dipstick guide hose.

Chain tensioners

BMW N42 engine has been exposed to oil leaks from rocker arm cover gaskets and VANOS solenoid seals. Genuine timing chain tensioners in BMW E46 318i (N42B20) can wear out and come loose prematurely. If this happens, the chain can slip and bounce one tooth at a time, which negatively affects the timing of the exhaust camshaft.

If the chain slips, it will cause the chain guide to breaking when the surface comes into contact with the chain. In the worst case, changing the valve timing of the exhaust valves can cause the valves to hit the piston crowns, causing the valve stems to bend – if this happens, the engine will need to be rebuilt. If the circuit is bouncing, the diagnostics may indicate a malfunction of the camshaft sensor. In 2003 BMW introduced longer chain tensioners. Electronics A manufacturing problem with the auxiliary cooling fan electronics, which could cause the fan to overheat, reduces the cooling system’s performance, causing the engine to overheat.

Crankcase breather valve

The PCV (forced crankcase ventilation) system separates the oil from the oily mixed air that creates pressure in the engine crankcase. Hoses and separators are susceptible to hot oil wear, which can build up inside and cause problems. Therefore, the PCV system should be considered a maintenance item and replaced regularly to prevent clogging of oil build-up from the air vents. A definite sign of clogging or narrowing of PCV components is that due to pressure, all seals around the crankcase (and this is the timing case, oil pan and especially the valve cover) begin to leak oil.

The problem is solved by purchasing a breather kit to protect the crankcase and then replacing it. Intake manifold flaps Special flaps in the intake manifold of the BMW 320d E46 close when the BMW M47 engine stops working. This is necessary to ensure a smooth stop of the engine by turning off the air supply (in a diesel car, it is impossible to turn off the ignition, as in gasoline engines, since there are no classic spark plugs, and combustion is carried out using the so-called self-ignition).

Unfortunately, these flaps tend to break, and the fractured parts fall into the engine cylinders, damaging the valves and the entire engine. An additional disadvantage of these flaps is that dirt builds upon them over time, leading to poor airflow to the engine and reduced power. On newer engines, this defect was eliminated by installing the flaps differently – so that they did not fall into the manifold.

Cooling system

The E46’s cooling system comprises plastic fittings, clamps and reservoirs, all of which are prone to cracking, causing severe coolant leakage and pressure drop issues. If there is coolant leakage, it is necessary to replace all critical points of the failed ones and flush the system with the original coolant.

Gearboxes

BMW E46 328i and 330i manufactured before January 2003 and equipped with a manual gearbox may have problems with the shift lever: hard to shift into and out of 5th gear; problem in shifting from 5th and reverse gears back to neutral;

This problem occurs due to the sticking of the fifth gear and reverse shaft pin due to faulty bushing installed in the bore of the gear selector shaft. It is necessary to replace the fifth and rear bushings of the gear shift shaft pin. On models with a manual transmission, drain plugs may also leak and must be replaced.

Cars with automatic gearboxes (325i from October 2002 to December 2003 and 330i from March 2003 to December 2003) may experience problems when shifting out of “park” after a cold start: there is a delay of 2 to 30 seconds when you turn on “drive”. This delay is caused by insufficient pressure increase for the front clutch C1 during the first “parking” to “drive” shift after an extended (for example, overnight) parking. The control unit needs to be reprogrammed to fix the control module with an automatic electronic transmission (“EGS”).

Automatic transmissions may also slip or illuminate the “Check Engine” lamp due to slipping torque converter clutch (TCC) or a malfunctioning TCC solenoid. Steering After 150,000 km, there may be a grating or noise from the steering pinion shaft when the steering wheel is turned from left to right.

The problem arises from insufficient lubrication of the steering gear shaft seal. To resolve the issue, you need to add fluid to the power steering to lubricate the gear shaft seal; otherwise, the steering rods wear out very quickly, and replacing them is not cheap. Vibrations in the steering wheel can be associated with poor insulation of the power steering pump.

Suspension

The rear differential transfers the torque load from the engine through the subframe and into the chassis. This constant load and unloading weaken the metal sheet around the rear subframe mountings, causing it to loosen and detach from the chassis.

Compared to the E36, the rear axle in the E46 has a cross member at the two front attachment points of the subframe – this cross member protects the front attachment points, thereby reducing the twisting effect on the sheet metal. As a result, the load at the front of the subframe is transferred to the rear left of the subframe and causes cracks in the sheet metal in this area. The E46 rear beam reinforcement kits have been developed to thicken the metal and distribute the load over a large area to solve this problem.

For 46 models from May 8, 2004, to June 22, 2004 – the holes in the wheel hub in the rim may be too small. As a result, the wheel may not make contact with the brake discs properly, and although the wheel bolts have been tightened to the correct torque, the wheel bolts may loosen.

Front axle gearbox output shaft

Front axles on all-wheel-drive BMW E46 are known for their problems, especially with external drive shaft joints and bellows. These problems are more common on low-slung cars, so it is essential to periodically pay attention to the hinges. If you notice in time, it is enough to replace the corrugated casing kit (external – 31607507402, which can most often give an unpleasant mood, and internal – 31607507403). If the cover is torn, there is a high chance that the joint is dry and contaminated with road dirt or sand. In this case, the tight connection will wear out quickly, and the entire axle will need to be replaced.

Rear subframe bushings (beams)

The rear axle beam receives a lot of loads in the BMW E46 from lateral movement. In addition to the subframe itself, the silent blocks take on a large load and subsequently wear out, which will cause impacts and a characteristic crackle and accelerate the wear of the subframe itself. Other symptoms can be discomfort during the ride from the rear suspension and a spontaneous increase in the angle of the rear wheels, which leads to rapid wear of the rear tires from the inside (even after 40,000 km, new tires can be completely worn out). In addition to reinforcing the subframe, it is a good idea to make sure that all bushings are usable.

Barrel-shaped rear spring

Rear springs are known to break at the bottom. This is because water and road salt will build up in this area and erode and weaken the steel spring, causing it to break during compression. Rear springs for rear-wheel-drive models are 33531095736, and for all-wheel-drive models 33536756975.

Elastic coupling

The vibration over the vehicle body may indicate a worn elastic coupling (26117511454) and a centre mount (26127501257) on the drive shaft. The primary function of the clutch is to absorb vibration, and when worn, it transmits vibrations to the entire chassis of the vehicle. If the clutch is not changed, it will burst and damage the pinion flange on the differential. Worn centre bearings will heat up and subsequently impede the drive shaft’s free rotation, which is fraught with severe problems.

Interior

On BMW E46 3 Series produced since June 1998, when driving at speed over large bumps, side airbags may suddenly deploy; the problem can be solved by reprogramming the airbag control unit. Cars built between December 2001 and March 2003, the front passenger airbag may be assembled with improperly manufactured propellant plates. In an accident, the inflator can burst and cause the airbag to deploy abnormally, increasing the risk of injury to the front passenger. BMW E46 manufactured from January 1, 2002, to December 31, 2005, in the presence of a high level of absolute air humidity, the gas generator of the driver’s airbag may malfunction.

Electrical part

If the “tail lamp out” indicator on the dashboard comes on, it may mean that the rear light cover needs to be replaced (left – 63 21 7 165 865, right – 63 21 7 165 866). This is a common problem and can be solved by replacing obsolete components.

Conclusion

In short, the BMW E46 is a car worthy of attention, and all problems in most cases are associated with wear and tear of parts and, perhaps, with age. If you service it on time by installing high-quality components, then the car will delight you for a long time.