2004 Mitsubishi Diamante

2004 Mitsubishi Diamante

Overview

The 2004 Mitsubishi Diamante, a mid-size sedan known for its comfortable ride and distinctive styling, generally presents a respectable reliability record for its era. While not without its quirks, many owners report a positive ownership experience, especially when routine maintenance is diligently performed. This analysis focuses on common reported issues beyond standard wear and tear, providing insights into potential areas of concern for prospective buyers or current owners. The Diamante was offered with a capable V6 engine and a smooth automatic transmission, contributing to its appeal as a refined daily driver.

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Engine

3.5L V6 (6G74)

Timing Belt Failure

• Symptoms: Sudden engine shutdown, loss of power, potential for severe internal engine damage if belt breaks.
• Solution: Replace timing belt and tensioner according to manufacturer’s recommended interval (typically around 60,000-90,000 miles).
• Cost: $600 - $1000

Oil Leaks (Valve Cover Gaskets)

• Symptoms: Visible oil on engine block, burning oil smell, potential for oil to drip onto exhaust components.
• Solution: Replace valve cover gaskets.
• Cost: $300 - $500

Transmission

4-Speed Automatic (F4A51)

Transmission Slipping

• Symptoms: Delayed engagement, difficulty shifting gears, engine revving without vehicle acceleration.
• Solution: Fluid and filter change, potential internal repairs or transmission rebuild.
• Cost: $400 - $2500+

Suspension

Standard Independent Suspension

Worn Ball Joints/Control Arm Bushings

• Symptoms: Clunking noises over bumps, vague steering feel, uneven tire wear.
• Solution: Replacement of worn ball joints and/or control arm bushings.
• Cost: $400 - $800

Electrical

General Electrical System

Power Window Actuator Failure

• Symptoms: Power windows not operating, slow or jerky window movement.
• Solution: Replacement of the power window motor/regulator assembly.
• Cost: $200 - $400

Instrument Cluster Malfunctions

• Symptoms: Dim or non-functional gauges, warning lights staying on, intermittent power to cluster.
• Solution: Repair or replacement of the instrument cluster.
• Cost: $500 - $1000

Exterior

Body and Trim

Clear Coat Peeling

• Symptoms: Fading paint, peeling clear coat, especially on horizontal surfaces like the roof and hood.
• Solution: Repainting affected areas or full vehicle repaint.
• Cost: $500 - $3000+

Interior

Cabin Components

HVAC Blower Motor Resistor Failure

• Symptoms: HVAC fan only works on the highest setting, or not at all.
• Solution: Replacement of the blower motor resistor.
• Cost: $100 - $250

Sunroof Mechanism Issues

• Symptoms: Sunroof not opening/closing properly, binding or grinding noises.
• Solution: Lubrication, adjustment, or replacement of sunroof components.
• Cost: $300 - $700

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Summary Verdict

The 2004 Mitsubishi Diamante is a generally reliable vehicle, with its V6 engine and automatic transmission proving to be fairly robust. However, owners should be aware of potential issues such as timing belt maintenance, oil leaks from valve cover gaskets, and occasional transmission slipping. Electrical components like power window regulators and instrument clusters can also develop faults. Exterior paint durability, particularly the clear coat, is a common concern for vehicles of this age. Interior issues are typically minor, with HVAC blower resistors and sunroof mechanisms being the most frequently cited. Proactive maintenance, especially regarding the timing belt, is crucial for long-term reliability.