1971 MERCURY COUGAR

Typical onset: 80,000-150,000 mi or age-related on low-mileage survivors

Symptoms: Engine rattling on cold start that quiets after warm-up, Poor idle quality and timing drift, Difficulty setting base timing accurately, Complete no-start if chain jumps timing

Fix: Replace timing chain, gears, and tensioner. Original single-row chains stretch badly. Front cover removal required; 6-8 hours labor for experienced tech. Double-row aftermarket replacement strongly recommended.

Estimated cost: $800-1,400

Symptoms: Headlight doors stuck open or closed, HVAC blend doors not switching modes, Erratic idle and throttle response, Hissing sounds under dash or hood

Fix: All rubber vacuum lines become brittle and crack with age. Vacuum-operated headlight system is particularly troublesome. Complete system overhaul involves tracing and replacing 15-20 individual lines; 4-6 hours labor plus headlight door actuator rebuild or replacement if damaged.

Estimated cost: $400-900

Symptoms: Overheating in traffic or hot weather, especially 429/460 engines, Boiling over after shutdown, Temperature creeping past 210°F on gauge, Heater not providing adequate warmth

Fix: Factory cooling often marginal for 429/460 engines. Requires radiator re-core or aluminum replacement, high-flow water pump, proper shroud installation, and 180°F thermostat. Inspect freeze plugs for seepage during work. 5-7 hours if doing comprehensive refresh.

Estimated cost: $1,200-2,200

Symptoms: Visible rust perforation in shock towers or torque boxes, Clunking over bumps that worsens progressively, Misalignment that won't correct, Cracking paint around inner fender wells

Fix: Salt-belt cars develop structural rust in shock towers, torque boxes, and front subframe rails. Repair requires cutting out rust and welding in patch panels or replacement sections. Professional metal work runs 15-25 hours depending on extent. Unibody structural integrity critical for safety.

Estimated cost: $2,500-5,000

Symptoms: Gauges reading intermittently or stuck, Turn signals or brake lights inconsistent, Ammeter showing discharge, Accessories working sometimes but not others

Fix: Five decades of corrosion on bullet connectors, fuse box contacts, and ground straps. Systematic cleaning of grounds, bulkhead connector service, and voltage regulator testing typically resolves most issues. Frustrating to diagnose; 3-6 hours troubleshooting and repair.

Estimated cost: $300-700

Typical onset: 70,000-120,000 mi

Symptoms: Fluid dripping from pump or gearbox seals, Groaning when turning at low speed, Steering effort increases when fluid low, Reservoir requires frequent top-ups

Fix: Ford Saginaw-style pumps and gearboxes develop seal leaks. Pump rebuild kits available; gearbox often needs complete replacement if internal wear present. Pump replacement 2 hours, gearbox 4-5 hours due to Pitman arm removal and alignment check afterward.

Estimated cost: $400-1,100

Typical onset: 90,000-140,000 mi

Symptoms: Delayed engagement into drive or reverse, Slipping between 1-2 shift under load, Burnt transmission fluid smell, No engine braking in manual 1st gear

Fix: C6 transmissions behind big-blocks take abuse. Forward clutch pack wear and modulator issues most common. Full rebuild required if clutches burnt; 10-14 hours labor for removal, rebuild, and reinstall. Torque converter replacement adds $300-500 to parts cost.

Estimated cost: $2,200-3,500