The 1979 Plymouth Arrow (rebadged Mitsubishi Colt/Lancer) is a fundamentally decent captive import let down by inferior U.S.-spec emissions controls, weak ignition components, and scarce body/trim parts that make cosmetic restoration expensive.
Silent Shaft Balance System Failure (2.6L 'Astron' engine)
Common · high severityTypical onset: 80,000-120,000 mi
Symptoms: Severe engine vibration especially at idle, Metallic rattling from lower engine, Oil pressure drop, Metal shavings in oil filter
Fix: The Mitsubishi 2.6L balance shaft chain and guides wear prematurely, especially if oil changes were neglected. Requires pan-off engine work or full teardown. 8-12 labor hours for in-chassis repair, often triggers full rebuild decision.
Estimated cost: $1,200-2,800
Jet Valve Failures (2.6L only)
Common · medium severityTypical onset: 60,000-90,000 mi
Symptoms: Ticking/tapping from cylinder head, Loss of low-end torque, Rough idle, Failed emissions test
Fix: The secondary 'Jet' valves (Mitsubishi's emissions band-aid) carbon up and stick or break. Requires head removal, valve job, and jet valve replacement. 6-8 hours labor. Often done alongside timing chain work.
Estimated cost: $800-1,400
Feedback Carburetor Electronics Meltdown
Common · medium severitySymptoms: Erratic idle, stalling when warm, Hesitation under load, Poor fuel economy, Check engine light (if equipped)
Fix: The primitive feedback carb system (oxygen sensor, control unit, stepper motor) corrodes and fails. NLA parts force owners toward Weber 32/36 or Holley 5200 carb swaps. Swap takes 3-4 hours, tuning another 1-2.
Estimated cost: $400-900
Timing Chain/Belt Guide and Tensioner Wear
Common · high severityTypical onset: 70,000-100,000 mi
Symptoms: Rattling on cold start that fades, Timing chain 'slap' sound, Hard starting when hot, Loss of power
Fix: All three engines have timing system weak points—1.6L/2.0L use belts that shed teeth if over-tensioned, 2.6L chain guides crack. Service interval should be 50k mi, not the factory 60k. 3-5 hours labor depending on engine.
Estimated cost: $350-750
Distributor Reluctor and Ignition Module Failure
Common · medium severitySymptoms: No-start when hot, starts fine cold, Random stalling, Backfiring through carb, Weak spark at higher RPM
Fix: Mitsubishi electronic ignition reluctors crack from heat cycles, modules fail intermittently. Diagnosis tricky without known-good spare parts. 1-2 hours labor plus parts that are now aftermarket-only quality lottery.
Estimated cost: $200-450
Body and Structural Rust (Northern/Coastal Cars)
Common · high severitySymptoms: Rust perforation in rear wheel arches, Rocker panel rot, Tailgate lower edge rot, Floor pan rust-through behind seats
Fix: Thin Japanese steel plus no factory rust protection equals disaster in salt states. Repair panels are NLA; requires fabrication. Expect 12-20 hours for competent patch work per side, more for show-quality.
Estimated cost: $1,500-4,000
Rear Axle Bearing and Seal Leaks
Occasional · medium severityTypical onset: 90,000-130,000 mi
Symptoms: Rear end whine or growl, Gear oil on inside of rear wheels, Wet brake shoes, Hot differential smell
Fix: Rear wheel bearings and axle seals leak, contaminating rear brakes. Bearings are pressed on, requires bearing puller and press work. 2-3 hours per side. OEM Mitsubishi bearings recommended over cheap imports.
Estimated cost: $300-600
Buy only if rust-free and you're handy with a wrench—parts scarcity and 2.6L gremlins make this a hobbyist-only proposition in 2025.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.