1971 PONTIAC FIREBIRD TRANS AM

Typical onset: 80,000-150,000 mi or unknown history

Symptoms: Heavy rod knock on cold start, Oil pressure drops below 10 psi at idle when hot, Metallic debris in oil filter, Visible scoring on crankshaft journals during inspection

Fix: Complete engine rebuild or replacement. Expect 40-60 hours for removal, machine work, reassembly, and reinstallation. Often triggered by years of irregular oil changes or running conventional oil in a high-mileage engine. Crankshaft may need grinding or replacement, rods checked for straightness, mains and rod bearings replaced, and often requires full piston ring job simultaneously.

Estimated cost: $6,500-12,000

Symptoms: Excessive driveline clunk on throttle engagement, Visible transmission sag when inspecting from underneath, Vibration at highway speeds, Shifter feels loose or notchy

Fix: Replace rubber transmission mount and inspect crossmember for rust-through. The original rubber mounts turn to powder after 50 years. Simple job at 1-2 hours labor, but crossmember rust can add complexity if structural welding needed. Always inspect frame rails while you're under there.

Estimated cost: $150-400

Symptoms: Hard starting after sitting, Rough idle and hesitation, Fuel weeping from carb base gaskets, Black crusty deposits around fuel inlet, Clogged fuel filter with green/brown debris

Fix: Modern ethanol fuel destroys original rubber components and leaves varnish throughout the fuel system. Expect to rebuild or replace the Rochester Quadrajet, replace all fuel lines, install inline filter, and clean the fuel tank. If the car sat for years, budget 8-12 hours for complete fuel system service.

Estimated cost: $800-1,800

Symptoms: Visible holes in driver/passenger floor pans, Soft or crusty metal along frame rails near subframe connectors, Water intrusion into interior, Failed jacking attempts due to weakened pinch welds

Fix: Northern cars or those stored improperly suffer severe rust. Floor pan replacement requires 20-30 hours and full interior removal. Frame rail repair may require subframe work and can easily exceed 40 hours if structural integrity is compromised. This is a deal-breaker repair on most projects unless you're doing it yourself.

Estimated cost: $4,000-9,000

Symptoms: Brake pedal goes to floor, Leaking wheel cylinders and calipers, Frozen parking brake cables, Master cylinder leaking into booster, Soft brake lines bubbling or weeping

Fix: Cars that sat for 10+ years need complete brake system overhaul: master cylinder, all four wheel cylinders or caliper rebuilds, all rubber flex lines, flush and bleed. Front disc brakes are more forgiving than rear drums. Budget 8-12 hours for full system refresh. Original single-piston calipers often have frozen pistons.

Estimated cost: $1,200-2,200

Symptoms: Running hot in traffic or on highway, Rusty coolant or pure water in system, Radiator core clogged internally, Water pump weeping from weep hole, Collapsed lower radiator hose under suction

Fix: The 455 runs hot by modern standards and the original cooling system is marginal. Expect to replace radiator (original copper-brass cores often clogged beyond repair), water pump, thermostat, hoses, and flush block. Verify fan clutch operation. Figure 6-8 hours for complete refresh.

Estimated cost: $900-1,600