The “75k Mile List”
E46 3 Series (1999-2005, including M) Edition
After years of driving, racing and repairing BMWs, we have clearly identified the common problems and maintenance concerns that need to be addressed on nearly every middle-aged BMW. E46 3-series cars, like all BMWs, have specific areas that need to be inspected regularly, and buyers should require a pre-purchase inspection to verify the condition of these areas.
In this list, you will find items that should have been replaced or at least inspected by 75k-100k miles. Some are model specific, and will be noted as such.
Areas of Concern:
Lower Control Arm Bushing Failure
Symptoms: Undesired front toe changes during cornering, vague and rubbery feel in steering, vibration while braking at freeway speeds. If you are experiencing any of these symptoms, you likely have a torn or cracked lower control arm bushing. Early model bushings are replaced with the larger late-model bushings for longer life. (Although the E36 is shown below, the E46 is similar.)
Rear Differential Mount Failure
Symptom: Thunking sound from the rear of your E46. Although mileage varies on Differential Mount failures, they are becoming more common. Because this can stress subframe mounting points and contribute to their failure, we recommend replacement at the earliest sign of failure.
Tie Rod Wear
Symptoms: Steering shimmy, clunking during steering input, inability to hold proper alignment. If any ball joint boot is cracked as indicated by grease coming out, it must be replaced. All components should also be checked for excessive play, and replaced if out of BMW spec.
Worn or Blown Shocks and Struts
Symptoms: Diving under braking and acceleration, excessive lean and suspension compression during cornering, bouncy and uncomfortable ride, shocks and struts visibly leaking shock oil. Factory BMW shocks work very well for 30k miles, but they quit by 60k miles. Because the deterioration is gradual, most BMW drivers hardly notice until the 60K mile mark. EDGE recommends replacing factory units with quality shocks from Koni whenever possible. When replacing shocks and struts, install lowering springs and adjust other areas of the suspension. You will be amazed at the difference a good set of shocks can make in both comfort and performance.
Worn or Failed Swaybar Endlinks
Symptoms: Metallic clicking noise and compromised handling. There is no critical danger in a failed swaybar endlink, but the handling of the car will be severely compromised. Ease of handling can be restored by simple replacement with new endlinks..
Torn Rear Trailing Arm Bushings (RTABs)
Symptoms: Car feels strange during cornering or excessive rear tire wear. Typical mileage for the RTAB replacement on E46 is approximately 35-45k. Failure to replace could lead to torn subframe and costly repairs. EDGE recommends replacement with factory units and RTAB limiting shims. The shims prevent excessive movement and can double the life of the bushing.
Torn Rear Shock Mounts
Symptoms: Pronounced clunking sound during suspension movement, sloppy and erratic handling, excessive rear suspension play. Torn or damaged rear shock mounts can tear right through the trunk carpeting into the passenger cabin, so any of these symptoms should be attended to right away.
Torn Subframe and Subframe Bushings
Symptoms: Erratic handling, unidentified clunking and banging sounds from rear of the car. Torn subframe bushings can lead to subframe failure. Early detection of a torn or cracked subframe bushing can prevent costly subframe repair and welding. Although problems occur primarily in tracked and autocrossed E46s, higher mileage E46s we have swapped out cracked bushings in higher mileage E46s as well.
Torn or Cracked Transmission Mounts
Symptoms: Hard, notchy, forced shifting while cornering, excessive shifter jerk during hard acceleration and braking, muddy shifter feel. Torn transmission mounts can lead to the dreaded ‘money shift,’ or mechanical overrev and probable destruction of the car’s motor. Worn transmission mounts allow for an excess amount of transmission movement. Stock replacements are just okay—we recommend stronger aftermarket replacements.
Ripped or Failed Guibo
Symptoms: Loud clunking sound before acceleration as the guibo bolts bind together. A torn guibo (Flex Disc) results in perceivable drivetrain elasticity.
Electronic Thermostat Failure
Symptoms: SES light appears, engine runs approximately 10 degrees hotter than normal, decreased fuel mileage.
E46s use electronically controlled thermostats which are prone to failure roughly every 60k miles.
Water Pump Failure
Symptom: Rapidly overheating motor. Water pump failure is the easiest way to cause extensive and expensive damage to your BMW. When the bearing or impeller on the stock pump breaks, it disables the cooling system and can result in a warped head or even more severe engine damage. If your temperature gauge climbs above the ¾ mark TURN THE CAR OFF IMMEDIATELY AND CALL A TOW TRUCK.
To prevent water pump failure, we recommend changing out the water pump on six cylinder cars every 60-80k miles.
Cracked Radiator Necks
Symptom: Possible drastic drop in coolant level, possible overheating motor, but often no symptoms showing whatsoever. Unfortunately for BMW owners everywhere, the makers of this beautiful car love plastic radiators. These radiators become brittle and crack with age, particularly around the neck and often without warning. To prevent costly repairs or devastating damage, radiators should be replaced routinely every 80-100k miles.
Electric Fan Failures
Symptom: Temperature climbing. Early E46 manual transmission cars have no engine-driven fan. They rely solely on the electric fan, which is prone to failure. If you see the temperature climbing, TURN THE CAR OFF IMMEDIATELY AND CALL A TOW TRUCK.
Cracked and Failed Thermostat Housings
Symptoms: Car running hot or cold.
For 6 cylinder cars only, the factory thermostat housing can eventually crack causing cooling system failure. Replacement with aluminum housing, or with the new composite units every 60k miles will prevent problems. We also recommend replacing the thermostat while the housing is off. All S50/52 and M50/52 thermostats should be replaced at the same interval of 60k miles. Sometimes they fail in the Open position (car runs cold) sometimes in the Closed position (car runs hot). If your temperature gauge climbs above the ¾ mark TURN THE CAR OFF IMMEDIATELY AND CALL A TOW TRUCK.
Fan Clutch Failure
Symptom: Fan clutch shows low resistance after driving (while engine is still warm) when manually turning the fan clutch. Most fan clutches fail between 80 and 100k miles. They provide the primary cooling for your car, and are easy for us to diagnose.
Accessory Belt and Tensioner Failure
Symptoms: Squealing noise from the engine bay and/or cracks in the belts, temperature gauge rising above the ¾ mark. If a belt snaps, the cooling system will fail as the water pump ceases to operate. Power steering and alternator will also fail. If you suspect belt failure or see the temperature gauge rise past the 3/4 mark TURN THE CAR OFF IMMEDIATELY AND CALL A TOW TRUCK.
Leaky Valve Cover Gasket
Symptom: Burning oil smell. Prevalent on all BMWs. If uncorrected, oil can seep into the spark plug holes and damage the ignition coils, resulting in costly replacement. Edge recommends replacing this inexpensive gasket when changing sparkplugs as the coilpacks will already be exposed.
O2 Sensor Failure
Symptoms: Poor mileage, poor idle and flat spots in the power curve. Even if your check engine light is on, your car may not be performing optimally. BMW recommends replacing the O2 sensors every 100k miles. Extended high-RPM running/racing and high-performance chips may shorten the replacement cycle.
Symptoms: For non-M BMWs, poor idle and periodic Check Engine lights showing. A deteriorated valve introduces a vacuum leak that will eventually cause the car to break down if neglected. Typical mileage is approximately 80k miles. Although the part is inexpensive, it requires approximately 4 hours of labor, depending on the year of the car.
Power Steering Lines
Symptoms: Difficulty steering, noises while turning, leaking fluid beneath car. The swedged ends on the BMW lines begin to seep and eventually leak heavily. Check your fluid often and look for leaks. When its time, replace all of them and the reservoir as it contains the filter for the system. This applies to all BMWs.
Clogged and Dirty Pollen Filter
Symptoms: Reduced flow of air from A/C or heater, and/or damp and musky smell. If either symptom is evident, it’s likely that the pollen microfilter of your car has become dirty and clogged over time. This is a service II replacement item.
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