bmw 3-series

bmw 3-series

If you are in the market for a used BMW 3-Series you want to keep in mind that maintenance will play the largest roll in cost of ownership for an aging BMW (or any car). We interviewed BMW experts and owners alike to compile the top 5 Things to Check when purchasing a 99 – 06 (E46) BMW 3-Series:

1. Power Window Regulators:

What it is: The regulator is mounted inside the door frame. Driven by a small electric motor, it allows the window to be raised and lowered via a window switch or button.

Why: On E46 BMW 3-Series, Power windows are a standard feature and a relatively common failure item. Window regulators should be replaced in conjunction with the electric window motor to prevent repeated repairs & save on future labor costs. In the event of regulator failure, the window will become stuck in the most inconvenient position imaginable – and it’s almost guaranteed to begin raining shortly there after.

Check: Actuate each of the power windows and observe their operation individually. The most common symptom is that the window will operate very slowly when being rolled up. Also be aware of any ‘skipping’ of the window or irregular noise during operation.

2. The Cooling System ‘Failure Trifecta’

What: BMW designs their engine cooling systems to maintain optimal operating temperate which provides for the best vehicle performance and greatest economy. The cooling system is responsible for circulating ‘coolant’ (50% Antifreeze, 50% Water) throughout the engine. This coolant mix absorbs and dissipates the heat created by the engine.

Why: Cooling system components are not designed to last forever. Due to the extreme fluctuation in temperature many components of this system, usually belts, become brittle and will need to be replaced at about 100k miles. This system is designed to be serviceable – but typically exhibits a domino-effect failure pattern. The three cooling components you need to know are: ‘Water Pump’ ‘Map Thermostat ‘ and ‘Expansion tank’. We highly recommend replacing these three in unison to avoid repeat repairs and save on labor time.

Check: Although it’s difficult to determine exactly when a part will fail, know you’re working with approximately a 80-100k mile component lifespan. This can vary so you should check for any current cooling system leaks by opening the hood (engine off, key out of ignition) and looking for any dried coolant – typically on the front of the engine. BMW coolant is a dark blue color in liquid form, but dries into a chalk-like white substance. (BMW’s use a mineral based coolant.)

3. Secondary Air Injection System

What: Responsible for injecting air into the exhaust stream during vehicle warm-up, this system is composed of an electric pump, exhaust valve, relay, and vacuum lines and works to lower the vehicles exhaust emissions by bringing the catalytic converters in the exhaust system up to operating temperature at a higher rate.

Why: Any failure in the secondary air system will store emissions related faults in the engine control module and will illuminate the ‘Check Engine’ light preventing the vehicle from passing inspection in some states. (Cough-Massachusetts-Cough)

Check: Observe the instrument cluster, if the check engine light is illuminated there is a possibility that this may be the failure you encounter. Note if the vehicle has a current inspection sticker – this can be an indicator of how well the emissions system is functioning (depending on your states inspection procedure). If you have access to an OBD2 scan tool or hand held code reader link to the vehicles engine control unit (called the DME by BMW) and check for fault codes. Most auto parts stores will check codes for free.

4. Rear ‘Sub Frame’ Damage

What: The rear sub-frame functions as the structure for the rear suspension in addition to the other crucial parts that mount to it. Responsible for distributing ‘chassis load’ it also serves to remove unwanted vibration from the vehicle.

Why: If the rear sub-frame or rear sub-frame mounting points on the vehicles body are damaged the vehicle is unsafe to drive. Although it is not an extremely common failure it has been recognized as one of the most expensive to remedy – requiring both mechanical disassembly & body shop work to correct.
Check: The best way to protect yourself from purchasing a 3-Series with sub-frame related damage is to have it inspected by your nearest BMW center or specialty BMW shop. If you do have the ability to gain access to the underside of the car, you can visually inspect the rear sub-frame-to-body mounting points for damage or torn sheet metal. Always use extreme caution when lifting cars. Do not attempt without the use of jack-stands and a floor jack. It’s best to use a lift with functioning safety locks.

5. Front Control Arm bushings

What: The control arm bushings are designed to isolate the vibrations caused by the road surface from the vehicle chassis and provide a quieter more comfortable ride.

Why: BMW E46 3-Series have 2 front control arm bushings mounting both left and right control arms to the body. These bushings are composed of an outer metal sleeve, a rubber bushing and a smaller inner metal sleeve. As the rubber bushing deteriorates over time it can effect wheel alignment, vehicle handling, steering and braking dynamics. Depending on driving style, front control arm bushings can be expected to last about 70-120k miles before requiring replacement.

Check: Again if you have (safe) access to the underside of the car, you can locate the front control arms and inspect the bushings visually for tears or cracking. You can also check the operation of the bushings by driving the vehicle (in a controlled environment ie: empty parking lot) at a low speed 5-10mph, and sharply applying the brakes. Listen for any clunking as you brake hard, and while the vehicle settles. Additionally, have a friend stand outside the car and observe the front wheels as you brake normally, if the front wheels appear to be ‘shuddering’ or skipping as you brake it’s a solid indicator of heavily worn control arm bushings!

Conclusion

If any of this sounds too complicated or you don’t feel comfortable checking a used BMW 3-Series yourself, we recommend going to a local mechanic you know and trust. Do this before buying any used car. It’s best if they know German cars if you want to purchase an E46 Bimmer. Any mechanic with a trained eye will be better than you.

Think we missed something on checking a E46 BMW 3-Series? Have a question about purchasing a BMW? Let us know below.

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James Garvey

James Garvey is a BMW of North America trained motorsport specialist, Aspiring Ferrari autocross driver, and destroyer of apex cones. Certified to aid Rick Ross should his Maybach break down. Seriously.

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