1973 PONTIAC GTO

Typical onset: original units often failed 60,000-90,000 mi; rebuilds last 40,000-70,000 mi depending on abuse

Symptoms: Slipping between 1st and 2nd gear under load, Red ATF pooling under bellhousing or dripping from cooler lines at radiator, Delayed engagement when shifting into Drive or Reverse after warm-up, Burnt fluid smell and dark brown ATF on dipstick

Fix: Full TH-400 rebuild with updated clutch packs and bands takes 8-12 hours; cooler lines rust through at radiator crimps and need replacement with braided stainless. Expect to pull the transmission, replace all seals, bands, and clutches. Most shops also replace the torque converter and external filter while they're in there. Cooler line replacement alone is 2-3 hours if caught early.

Estimated cost: $2,200-3,800

Typical onset: manifests around 80,000-140,000 mi on original engines; accelerated by irregular oil changes

Symptoms: Oil pressure dropping below 10 psi at hot idle, Rod knock audible on cold starts that quiets slightly when warm, Metallic debris on magnetic drain plug during oil changes, Blue smoke on deceleration indicating worn valve guides or ring seal

Fix: These Pontiac V8s have long crank journals and heavy pistons that hammer bearings when clearances open up. A proper fix requires pulling the engine for main and rod bearing replacement with crank inspection and possible turning — figure 18-24 hours for engine removal, bearing replacement, decking, and reinstallation. If the crank is scored beyond .030 under, you're looking at a full rebuild with pistons and rings. Many owners just swap in a rebuilt long block to save diagnostic time.

Estimated cost: $3,500-6,500

Typical onset: not mileage-specific; occurs after years of neglected coolant service and sediment buildup

Symptoms: Temperature gauge climbing into red zone in traffic or on hot days, Coolant weeping from water pump weep hole below pulley, Gurgling sounds from heater core after shutdown, Lower radiator hose stays cool while upper hose is scalding

Fix: The 455 V8 in particular runs hot and the original 2-row radiators are marginal. Water pump replacement is 2-3 hours; radiator recore or upgrade to 3-row aluminum is another 3-4 hours. Shops usually replace hoses, thermostat, and flush the block at the same time. The factory 160°F thermostats often stick partially closed after decades. Budget for a complete cooling system refresh if any component fails.

Estimated cost: $800-1,600

Symptoms: Raw fuel smell in garage after sitting overnight, Hard starting when hot, starts fine cold, Black smoke from exhaust under acceleration, Engine dying at idle after initial start, Fuel puddling on intake manifold around carb base

Fix: The Rochester Quadrajet carburetors used in 1973 have nitrophyl floats that absorb fuel over time and sink, causing flooding. Ethanol fuel eats the rubber accelerator pump and power valve diaphragms. A proper rebuild with modern ethanol-resistant kit takes 4-6 hours including removal, bench rebuild, reinstallation, and tuning. Some techs prefer swapping to an Edelbrock 600 cfm to eliminate future headaches — same labor, $400 for the carb.

Estimated cost: $500-900

Typical onset: mounts fail every 40,000-60,000 mi or 8-12 years due to heat from exhaust proximity

Symptoms: Clunk when shifting from Park to Drive or Reverse, Vibration at 45-55 mph that wasn't there before, Visible tailshaft droop when inspecting under vehicle, Exhaust rattling against crossmember or floorpan

Fix: The rubber transmission mount sits directly above the exhaust crossover and cooks into a hockey puck. Replacement is straightforward — support the tailshaft with a jack, unbolt old mount, bolt in new polyurethane unit. Most shops knock this out in 1 hour. Do motor mounts at the same time if they're original; adds 2 hours labor but prevents comebacks.

Estimated cost: $150-350

Symptoms: Engine stumbles or dies in hot weather after extended idle, Difficulty restarting after filling fuel tank, Surging at highway speed on hot days, Fuel pump running constantly or clicking rapidly

Fix: The mechanical fuel pump mounts on the timing cover and absorbs tremendous heat, boiling fuel in the lines. The inline filter clogs with rust from old steel tanks. Replace the filter first (0.5 hours), then inspect rubber fuel lines for cracking. If vaporlock persists, install an electric pump near the tank with return line — that's 3-4 hours. Many owners wrap fuel lines with heat shield tape as a preventive measure.

Estimated cost: $200-700