2004 BMW 645Ci
2004 BMW 645Ci
Overview
The 2004 BMW 645Ci, a luxury grand tourer, offers a blend of performance and comfort. Powered by a potent V8 engine and available with a smooth automatic transmission, it aims for a refined driving experience. While generally well-regarded for its design and driving dynamics, like any vehicle of this age and complexity, it has specific areas that have shown a propensity for issues. Owners should be aware of potential problems primarily related to the engine’s cooling system, electronic components, and some interior wear, particularly given its age and the sophisticated technology integrated into the vehicle.
Engine
4.4L V8 (N62B44)
Cooling System Leaks (Water Pump, Hoses, Thermostat)
- Symptoms: Coolant leaks, overheating, steam from engine bay, low coolant level warnings.
- Solution: Replacement of leaking components such as the water pump, thermostat housing, or coolant hoses. Regular coolant flushes are recommended.
- Cost: $800 - $1500
Valve Stem Seals
- Symptoms: Blue smoke on startup or when decelerating, increased oil consumption.
- Solution: Replacement of valve stem seals. This is a labor-intensive job.
- Cost: $2500 - $4000
Oil Pan Gasket Leaks
- Symptoms: Oil spots under the vehicle, low oil level warnings.
- Solution: Replacement of the oil pan gasket. May require dropping the subframe.
- Cost: $700 - $1200
Transmission
6-Speed Automatic (GM 5L47)
Mechatronic Unit Failure
- Symptoms: Harsh shifting, transmission warning lights, inability to select gears, slipping.
- Solution: Repair or replacement of the mechatronic unit. Transmission fluid and filter service is crucial.
- Cost: $1500 - $3000
Torque Converter Issues
- Symptoms: Shuddering at low speeds, slipping, delayed engagement.
- Solution: Replacement of the torque converter. Often done in conjunction with transmission service.
- Cost: $1200 - $2000
Suspension
Standard Chassis
No Major Issues
- Symptoms: No widespread issues reported.
- Solution: No widespread issues reported.
- Cost: No widespread issues reported.
Electrical
General Electrical System
CCC (Car Communication Computer) / iDrive Malfunctions
- Symptoms: Screen freezing, system reboots, navigation issues, audio problems.
- Solution: Software updates, module repair, or replacement of the CCC unit.
- Cost: $800 - $2500
Window Regulator Failure
- Symptoms: Power windows not operating, windows getting stuck.
- Solution: Replacement of the window regulator mechanism.
- Cost: $300 - $600
Battery Drain Issues
- Symptoms: Dead battery, electrical components malfunctioning intermittently.
- Solution: Diagnosis to find parasitic draw, replacement of faulty modules or wiring.
- Cost: $400 - $1000
Exterior
Body and Trim
No Major Issues
- Symptoms: No widespread issues reported.
- Solution: No widespread issues reported.
- Cost: No widespread issues reported.
Interior
Interior Components
Headliner Sagging
- Symptoms: Fabric detaching from the headliner board, especially in warmer climates.
- Solution: Re-gluing or replacement of the headliner.
- Cost: $300 - $700
HVAC Blower Motor Resistor Failure
- Symptoms: Fan only works on certain speeds or not at all.
- Solution: Replacement of the blower motor resistor.
- Cost: $150 - $300
Summary Verdict
The 2004 BMW 645Ci is a capable grand tourer, but its advanced technology and V8 engine mean potential owners should budget for maintenance and repairs. The most significant concerns revolve around the cooling system, with leaks being common due to age and material degradation. Valve stem seals and oil pan gaskets are also known weak points that can lead to costly repairs. Transmission issues, particularly with the mechatronic unit and torque converter, can arise. Electrical gremlins, especially with the iDrive system and battery drain, are not uncommon. While the suspension and exterior are generally robust, interior components like the headliner can show wear. Regular, proactive maintenance is key to mitigating these potential issues and ensuring the longevity of this luxurious coupe.