Top 10 E46 Failures
These 10 parts will certainly fail on you
These 10 parts will certainly fail on you
(For easier reading and info where to buy the parts, you can also find this post at my blog here.--Updated 9/27/16)
The BMW E46 3-Series produced from 2000 to 2006 is one of the more reliable BMWs you can buy. However, there are parts that will fail causing you to be stranded and/or cause major problems, including fires or destruction of more expensive components. These are the 10 most important and common failures on the BMW E46 platform.
You may have read my widely distributed and viewed post on the BMW E46 Cooling System detailing the common failures and the catastrophic results a single failure can result in, or you may have read my other posts on E46Fanatics.com which recommend full system replacements rather than picking, choosing, and replacing each individual part as they fail. I highly recommend you check out those threads including the links in my signature.
However I realize not everyone can afford to replace $3,000 worth of parts to restore their BMW E46 3-Series back to reliable and well handling condition. So I've created a top 10 list of must-replace items for your BMW E46 3-Series. These parts are the 10 failures of the E46 platform and are certain to leave you stranded, frustrated, or leave your car with dangerous sloppy handling. This is a great and inexpensive way to begin your BMW E46 adventure. Take it from me, I've replaced all these immediately upon purchasing my E46 and have never experienced a single breakdown or failure.
This is not meant to be a guide to every possible part to fail, just what I think the most commonly failed parts that make a significant impact on the reliability or safety of your BMW E46.
Number One - Expansion Tank
While I still recommend full replacement of the E46 cooling system, the expansion tank is an absolute must. It is not optional and it should 100% absolutely be replaced upon your purchase of an E46. Do NOT skimp on this. The common failure is for the tank to develop a hairline crack down the side of the tank resulting in a low coolant light and shortly (seconds) after that, an engine overheat which will destroy your soft aluminum engine in mere seconds. Many have been in big trouble because they've neglected to replace this $60 part. The links are to OEM expansion tanks. Do not buy this part aftermarket.
Number Two - A/C Blower Final Stage Resistor
This part fails on ALL BMW E46s. And E36s for that matter. The BMW E46 Final Stage Resistor is responsible for your A/C Blower Fan speed. The failure is erratic fan speed behavior or the fan completely failing to turn on. This is torture on a hot summer day. This failed part has also been known to cause car fires. Very dangerous.
Number Three - Fuel Pump
Experiencing long cranks? Hard starts? Does your engine just crank and crank but doesn't turn over? If you haven't experienced any of these symptoms, you will. This failure will happen. Don't forget the seal. Link to OEM fuel pump here.
Number Four - Throttle Body Intake Boots
Very common failure. The boots that connect your air filter box to your throttle body dry out and crack over the years. Will cause vacuum leaks and subsequent lean codes P0174. The symptom is poor fuel mileage and/or stumbling, idling problems and stalling. Replace your upper and lower intake boots. Cheap stuff. Don't skimp. Make sure you align the tab on the lower boot with the space on the throttle body. Very easy install.
Links to boots:
E46 323/325/328 set: lower and upper
E46 330 set: lower and upper
Number Five - Crankcase Vent System
Will certainly fall causing a vacuum leak. Poor idling, stumbling, poor fuel mileage, or even smoke out the exhaust at startup. Rubber and plastic cracks and fails over time. Replace it once and never touch it again. Buy it here on FCPEuro.com.
Bonus: Don't forget to replace the vacuum tubing that connects to the F connector to semi-hard line that goes to the fuel filter.
Info credit to HodgkinsC330i: Hose diameter: 5/32", available from O'Reilly part# P3340: $3.49 - Product Description: Thermoid Windshield Washer & Vacuum Tubing 5/32" x 6'
Post here showing diagrams of the system (see post #6): http://www.bimmerfest.com/forums/sho...d.php?t=574814
Number Six - Front Control Arm Bushings (FCABs)
The rubber in your front control arm bushings rot over time and will cause sloppy and loose steering/handling. If totally failed, your suspension will clunk as you brake and your entire front wheel will move forward 1 to 2 inches -- very dangerous at highway speeds as the wheel will turn violently when you hit the brakes. If you can't brake, you may crash. Easy install, two bolts hold it on. Get a 3-jaw puller and pull the old one off. Spray windex or soapy water on the new bushing and tap it on with a rubber mallet. Torque it down and enjoy your new handling. I recommend Meyle HD
Number Seven - Rear Trailing Arm Bushings (RTABs)
Same as above. These rot out and cause sloppy rear handling. Replace every 50,000 miles or 35,000 miles if you are really picky. These are responsible for rear wheel toe control. Give your car gas and if the rear end wags under acceleration, your bushings are toast. Very dangerous if they fail.
Bonus: I recommend M3 rear trailing arm bushings as an upgrade for more solid handling. Direct fit. Plug and play. This kit comes with the famous shims for even greater control.
If you want to do these yourself, I recommend an RTAB tool. You can also search Google for an "MIS RTAB tool."
Install tip: Don't over-concern yourself with finding the magical mythical tool or technique to eliminate pre-load on your RTAB install. This isn't a big of a deal or that precise of a job people make it out to be. And coming from me, Mr. Precise, that should tell you something. If you have the magical alignment tool, great. Use it. If not, no big deal. Simply take note of the angle of the RTAB bracket in relation to the trailing arm. Mark it with a pen, take a photo, whatever. And simply re-torque the new RTAB in place with the bracket at the same angle as when you removed it. Voila! Every time I have done this job, the bracket always comes out perfectly lined up with a casting line of the actual trailing arm. I've often used that as a guide. Either way, I don't think millimeter precision is required here. The rubber is really flexible and your rear wheels are in a constant state of movement as you drive down the road or load your car up with passengers. I also doubt BMW factory workers are installing the RTABs with 100% millimeter precision every time. There's always going to be a +/- range of accepted tolerance with these types of things. If you're a fanatic, you should be able to get within that range. Eyeballing these should work just fine.
Number Eight - Alternator with Voltage Regulator
Battery light flickering? Constant dead batteries? Even if you don't experience those symptoms, you will. It's usually the voltage regulator that fails, but many just replace the alternator which will include a new voltage regulator (it's bolted to it.) Many figure "why not?"
MAKE SURE YOU GO LOOK AT YOUR CAR TO SEE WHAT CONNECTOR YOU HAVE. SQUARE OR ROUND? Also install the same or higher amperage as what your car came with.
More common square plug alternator for 325 and 330
Less common round plug alternator for 325 and 330
323/328 square 3-pin alternator
Number Nine - Pulleys and Belts
These pulleys carry your belt system and will dry out and rot over time. Do your pulleys sound like skateboard wheels when spun? Does your engine make a squeaky noise as it runs? Your pulleys are ready to fail. When they do, it will throw the belts off and take your engine down with it. Instant overheat. Instant engine rebuild. Don't risk it. Don't forget to get new belts. You may as well.
See my thread here for what parts you need and where to buy them: http://www.e46fanatics.com/forum/showthread.php?t=974746
Number Ten - Battery - Autozone H8 DLG
Very simple. Replace with a battery from your local parts store. Personally I went with Autozone brand -- paid $200 for my battery. You may be able to find it for $150.
If any corrections need to be made, feel free to let me know! Thanks.