1974 MERCURY COUGAR

Typical onset: 80,000-140,000 mi

Symptoms: Rough idle and hard starting when engine is hot, Backfiring through carburetor on deceleration, Rattling noise from front of engine at startup, Retarded ignition timing that won't advance properly

Fix: Replace timing chain, gears, and tensioner; many techs replace oil pump gear and check camshaft end-play at the same time. Count on 6-8 hours labor for 351 engines, 8-10 hours for big-blocks due to tighter clearances and accessory removal. Use double-roller aftermarket chains, not OEM single-row.

Estimated cost: $800-1,400

Symptoms: Erratic idle speed or stalling when warm, Poor fuel economy and hesitation on acceleration, A/C or heater blend doors stuck or inoperative, Headlight doors (hideaway) slow or non-functional

Fix: 1974 had a maze of vacuum lines for EGR, distributor advance, HVAC, and headlight doors. Every rubber line is 50 years old—expect wholesale replacement of vacuum hose, check valves, and diaphragm actuators. Budget 4-6 hours to diagram, replace, and test all circuits; vacuum-operated headlight systems often need new servos.

Estimated cost: $400-900

Symptoms: Black smoke and fuel smell at idle, Stumble or bog on hard acceleration, Flooding after hot shutdowns, High idle that won't come down

Fix: The Motorcraft spreadbore carbs used in '74 suffer accelerator pump wear, warped throttle shafts, and clogged emission ports. Most need complete rebuild kits and careful float adjustment; many owners swap to Edelbrock or Holley for reliability. Professional rebuild runs 3-4 hours; conversion kit install 2-3 hours.

Estimated cost: $350-700

Symptoms: Overheating in traffic or on hills, Coolant weeping from radiator seams, Sweet smell and wet passenger-side carpet (heater core), Steam from defrost vents

Fix: Original copper-brass radiators leak at 50+ years; aftermarket aluminum replacements are common. Heater core replacement requires full dash removal on Cougars—it's an 8-10 hour nightmare. Radiator swap is straightforward at 2-3 hours. Always replace hoses, thermostat, and water pump at same time if original.

Estimated cost: $600-2,200

Typical onset: 100,000+ mi

Symptoms: Rear end sits low or leans to one side, Harsh ride over bumps with metal-on-metal clunking, Tire wear on inside edges of rear tires, Trunk floor shows rust around shock towers

Fix: Leaf springs lose arch over decades; shock mounts rust through on cars stored outdoors. Spring replacement is 3-4 hours; if shock towers need welding and reinforcement, add 4-6 hours of metal fabrication. Many upgrade to Mustang II front suspension kits while at it.

Estimated cost: $700-1,800

Typical onset: 90,000-150,000 mi

Symptoms: Steering wheel requires constant correction on highway, Power steering fluid drips from steering box, Groaning noise when turning at low speed, Excessive play—more than 2 inches at wheel rim

Fix: Ford integral power steering boxes wear internally and leak from sector shaft seal. Rebuild kits exist but most opt for reman unit at 3-4 hours labor. Inspect rag joint and steering column coupler for wear at same time—they fail together. Align afterward.

Estimated cost: $500-950

Typical onset: 80,000+ mi

Symptoms: Delayed engagement into Drive or Reverse after overnight sit, Pink fluid spots under car after parking, Whining or growling from transmission at highway speed, Burnt smell from transmission after hard pulls

Fix: Torque converter check valves fail, causing slow fill on startup; front pump seals and pan gaskets leak. Converter replacement requires trans removal (6-8 hours). Reseal with new pan gasket, filter, modulator, and 12 quarts of Type-F fluid. If growling persists, internal hard parts are next.

Estimated cost: $800-1,600