1977 PONTIAC SUNBIRD

Typical onset: 80,000-120,000 mi

Symptoms: excessive oil consumption (1 qt per 500-800 miles), blue smoke on startup and acceleration, rod knock or bottom-end noise, loss of compression, hard starting when warm

Fix: Weak piston rings and cylinder wall glazing were endemic to these Pontiac and Chevy four-bangers. Most need a full rebuild (bore, new pistons, rings, bearings) by 100k. Budget 18-24 labor hours for a proper overhaul or 12-16 for a short block swap if cores are available.

Estimated cost: $2,200-3,800

Typical onset: 70,000-110,000 mi

Symptoms: delayed engagement into Drive or Reverse, slipping between 1-2 or 2-3 shifts, no movement in any gear, burnt transmission fluid smell, whining or grinding noises

Fix: The TH-200 behind four-cylinders is notoriously fragile; clutch packs and sun shell failures are typical. TH-350s hold up better but still need rebuilds by 100k due to worn clutches and seals. Full rebuild requires 8-12 hours; add 2-3 hours if the oil cooler lines or radiator cooler are leaking (common). External cooler addition is highly recommended.

Estimated cost: $1,400-2,600

Symptoms: hard starting when cold or hot, rough idle and stalling, flooding and fuel smell, hesitation on acceleration, black smoke from exhaust, poor fuel economy (sub-15 mpg)

Fix: The Rochester 2GC two-barrel and Varajet carbs are vacuum-nightmare setups plagued by worn throttle shafts, gunked passages, and failed EGR valves. Most need a full rebuild kit and EGR valve replacement, plus vacuum line renewal. Figure 3-5 hours for a thorough carb overhaul and vacuum system diagnosis.

Estimated cost: $350-700

Typical onset: 90,000-140,000 mi

Symptoms: whining or howling from rear end that changes with speed, clunking on acceleration or deceleration, vibration at highway speeds, gear oil leaks at pinion seal or axle seals

Fix: The 7.5-inch rear end uses tapered wheel bearings that wear and cause noise; pinion bearings also fail. A full bearing replacement with new seals runs 4-6 hours. If ring-and-pinion are damaged, add another 2-3 hours for setup and shimming.

Estimated cost: $500-1,100

Symptoms: visible rust holes in floor pans behind front seats, soft or spongy floors when pressed, rust perforation around rear shock towers, rust on front subframe and torque boxes, water intrusion into interior

Fix: All H-bodies rust badly in the floors, rockers, and front subframe. Floor pan replacement requires welding and is labor-intensive (12-20 hours depending on scope). Subframe rust compromises steering and suspension mounting points and is not economically repairable on most examples. Inspect thoroughly before purchase.

Estimated cost: $1,800-4,500

Symptoms: fuel starvation at low fuel levels, fuel pump failure (mechanical or in-tank on some models), clogged fuel filter within 5,000 miles, rust particles in fuel filter, fuel smell inside car from leaking filler neck

Fix: Original steel tanks rust internally after sitting or from condensation; rusty filler necks and sending units also leak. Tank replacement with new sending unit and fuel lines runs 4-6 hours. Mechanical fuel pump replacement is 1-2 hours but often masks a tank issue.

Estimated cost: $400-900

Typical onset: 80,000-130,000 mi

Symptoms: hard shifting or grinding into second gear, popping out of second or third gear under load, gear clash when downshifting, whining in certain gears

Fix: Second-gear synchros wear first in these Saginaw boxes, especially with the torquey 305 V8. Rebuild with new synchro rings, bearings, and seals takes 6-9 hours. These transmissions are relatively simple and parts are available, but labor adds up.

Estimated cost: $900-1,600