The BMW E46 is a high-performance German sedan/coupe that is now coming down in price to allow it to fall into a completely new market. Offering great bang for the buck, it’s important to realize that a car built to these tight tolerances requires quality maintenance to avoid major headaches. Here’s a list of the BMW E46 Common Problems, so you can keep in mind probable repairs you may have to accomplish during ownership of an BMW E46 3-series.
1. Cooling System Failure/Leaks from Plastic Components:
The E46 cooling system is full of plastic fittings, clips, and reservoirs that all have a habit of cracking, causing major problems with coolant leaks and De-pressurization. eEuroparts sells a kit to replace all the key failure points at once, and includes genuine BMW coolant to flush the system when done. The number for the eEuroparts.com BMW E46 3-series cooling system refresh kit is 100k10097.
2. Weak Rear Shock Mount
In addition to reinforcing the rear sub-frame, the shock mount is another area that can use a little love. eEuroparts sells a part that reinforces the rear shock mounts, and it is straight from BMW. The rear shock mount reinforcement also fits E30’s, E36’s and Z3’s as well, and fits on TOP of the mount on the interior of the car. The original design focuses on the bottom of the mount, where the weight of the car sits, but has no emphasis on the top. This makes unloading the suspension potentially hazardous to the other side of the shock tower.
If you are doing a rear shock mount, there’s no reason NOT to bolt on this reinforcement. Because of this, we sell the shock mounts, gaskets, nuts, and reinforcements together as a kit- 100K10157. This will beef up your suspension mountings and let you focus on other areas of the car.
3. Tail Light Failure
An intermittent ‘tail lamp out’ indicator on your dash could mean a few things, but hands down the most common failure involves the circuit boards inside the tail lights. This is so common that we made a complete kit to replace your components with uprated parts, including a wiring harness that is more capable of handling the heat and current of normal usage. I wrote a DIY blog on the subject, which you can read here [click here]. The surprisingly cost effective kit (100k10107 BMW Tail Light Repair Kit (E46)) includes new Genuine BMW taillight circuit boards for both sides of the car (63217165865 and 63217165866), as well as a Genuine BMW wiring repair kit (61129281435). We also offer the connectors (12527519956) and the corresponding terminal pins (12521433217) in case yours is melted, which is common.
4. Crankcase Vent Valve Failure/Maintenance:
The PCV (Positive Crankcase Ventilation) system is meant to separate the oil out of the oily stirred up air that pressurizes the crankcase of the engine due to piston blowby. The hoses and separator therefore see a lot of action when it comes to hot oil, which can build up inside and cause problems. Due to this, the PCV system should be considered a maintenance item, and replaced regularly in order to prevent sludgy buildup from clogging oil vent passageways.
A sure clue of clogged or constricted PCV components is that the seals around the crankcase will all start weeping oil due to the pressure that is not allowed to be vented. This includes the timing cover, oil pan, and especially the valve cover. We have two kits for the M54 and M52 6 cylinder engines found in the BMW E46 3-series. They are 100K10104, and 100k10237 for cold climates. The second kit features insulated hoses to prevent water condensation from contributing to sludge buildup. You can read the DIY blog about this here: [click here]
5. Torn Front Axle Boots / Front Axle Failure (Xi AWD models only):
The front axles on these cars are notorious for having problems, specifically with the CV joints and related boots. These problems are accelerated with lowered cars, so it’s important to pay attention to the CV axles on your all-wheel drive model. If you catch it early, you can get away with just replacing the boots. The boot isn’t super easy to replace, because in order to do so you must remove the axle. However, replacing both axles at a dealer will run you more than $1700. Replacing four CV boots (each axle has an inner and an outer CV joint) will cost under $100 and a few hours of time. The CV Boot numbers are 31607507402 for the outer (the more common to fail) and the inner is 31607507403.
If the boot has been torn for a while, there is a high probability that the joint has run dry and been contaminated with dirt, grit, and road grime. In this case, the tight tolerance joint wears out quickly and the entire axle will need to be replaced. We have two front axles available for the E46 AWD, a cost effective Empi as well as a higher end GKN axle. The Empi numbers are A807916 for the front driver side, and A807917 for the front passenger side. The GKN front axles for the BMW 325xi and 330xi are 31607505199A for the front driver side, and 31607505200A for the front passenger side.
6. M3 Camshaft Gear Bolt Failure
The S54 engine has been known to have the cam gear bolts break. It is recommended to have these replaced every 30,000 miles at the same time as the valve adjustment. If one or more do break there would be catastrophic engine damage. We sell a kit with all of the necessary hardware, 100K10240, that comes with the necessary Loctite® thread locker.
7. Engine Oil Filter Housing Gasket
As with all gaskets, the oil filter housing gasket, part# 0816965, is a common failure point. This gasket will harden over time from the heat cycles produced by the engine and oil contaminants causing it to leak. If you see oil on the driver side portion of the engine block near the oil filter you know this gasket is leaking. Depending on the size of the leak, this may also cause the low oil light on the dash to illuminate.
8. Rear Sub-frame Bushing Failure
Like mentioned above, the rear subframe takes a lot of abuse in these cars from lateral movement. Besides the subframe itself, the bushings take a ton of abuse and subsequently wear out. When the bushings wear out, it will cause clunking and banging, and accelerate wear on the subframe itself. Aside from the sub frame reinforcing, it’s a good idea to make sure your bushings are all fresh to keep the car from hammering and banging itself apart. The key bushings to look at here are in this kit we put together, 100K10187.
9. Rear Spring Failure
The rear springs are notorious for breaking on the bottom coil where it sits on the control arm. This is due to the fact that water and road salt will collect in this area and corrode and weaken the steel spring causing it to eventually break as it compresses. The rear springs for rear wheel drive models are 06165. The rear springs for the all-wheel drive models are 06254.
10. Driveshaft Flex Disc / Center Support Bearing Failure
Driveline vibration which can be felt through the body of the vehicle may hint at a worn flex disc and support bearing on the drive shaft. The main function of the flex disc is to absorb vibration and as this item wears it transmits those vibrations throughout the chassis of the vehicle. If left un-repaired, the disc will actually start to tear and can damage the pinion flange on the differential. Worn center bearings will heat up and bind which will prevent the drive shaft from rotating freely, and can cause catastrophic failure.
Rear wheel drive vehicles will use Center Bearing 26127501257 and Auto Trans Flex Disc 26117511454, and the kit is 100K10241. Manual Transmission cars use Flex Disc 26111227410 and that kit is 100k10242. All-wheel-drive vehicles will use Center Bearing 26121229317 and Flex Disc 26111229360, and the kit for these cars is 100k10243.