1972 PONTIAC FIREBIRD

Typical onset: 80,000-120,000 mi

Symptoms: Slipping between 1st and 2nd gear under load, Delayed engagement when shifted into drive, Burnt transmission fluid smell, Metal shavings in pan during service

Fix: The TH400 behind the 400/455 V8s eats clutch packs and bands, especially if not serviced every 30k. Full rebuild runs 12-16 hours with torque converter replacement. Transmission mounts fail concurrently due to vibration, add 1.5 hours.

Estimated cost: $2,200-3,800

Typical onset: 90,000-140,000 mi

Symptoms: Blue smoke on startup that clears after warmup, Oil consumption 1+ quart per 500 miles, Fouled spark plugs on cylinder 3 and 5, Low compression readings under 110 psi

Fix: The 350/400/455 engines from this era used soft piston rings and brittle valve seals. Requires engine removal (8-10 hours), complete teardown, hone cylinders, new rings, bearings, seals, and gaskets. Budget 40-50 hours total for proper rebuild.

Estimated cost: $4,500-7,500

Symptoms: Oil puddles under rear of engine after overnight parking, Oil coating on bellhousing and starter, Wet oil pan rails visible from underneath, Losing 1 quart every 200-300 miles

Fix: The rope-style rear main seal hardens and shrinks after decades. Requires transmission removal for rear main (10-12 hours), oil pan gasket can sometimes be done with engine in place (4-6 hours) but front crossmember often needs dropping. Do both simultaneously.

Estimated cost: $1,200-2,400

Symptoms: Hard starting when cold, requires pumping throttle, Rough idle that smooths at 1500+ RPM, Hesitation or stumble during acceleration, Gas smell from carb bowl vents

Fix: Rochester Quadrajet carburetors gum up from ethanol fuel and sitting. Needs complete disassembly, ultrasonic cleaning, new gaskets, accelerator pump, and needle/seat. Replace fuel filter and check tank for rust. 4-6 hours for carb rebuild and system flush.

Estimated cost: $600-1,200

Symptoms: Visible rust perforation on front subframe rails, Cracking paint or bubbling around rear torque boxes, Clunking over bumps from weakened attachment points, Difficulty aligning front end after suspension work

Fix: Northern and coastal cars suffer subframe rot where front lower control arms mount. Torque boxes (where rear leaf springs anchor) rust from inside out. Proper fix requires frame-off work, cutting out bad metal, welding in patches or replacement sections. 20-40 hours depending on severity.

Estimated cost: $3,000-8,000

Typical onset: 60,000+ mi

Symptoms: Ticking noise from engine bay that increases with RPM, Exhaust smell in cabin during warmup, Visible cracks in cast iron manifold, Broken or stripped manifold mounting studs

Fix: Cast iron manifolds crack from heat cycles, especially on 400/455 engines. Studs break in aluminum heads during removal. Aftermarket headers are common upgrade ($300-600). Manifold replacement with stud extraction and helicoil inserts runs 6-8 hours per side.

Estimated cost: $800-1,600