1991 AUDI 80

Typical onset: 80,000-150,000 mi

Symptoms: white smoke from exhaust, coolant loss with no visible leaks, oil mixed with coolant in reservoir, overheating under load, rough idle after warming up

Fix: The plastic coolant flanges crack, radiators clog, and water pumps fail — often unnoticed until the head gasket lets go. If caught early, it's a thermostat/flange/radiator job (3-5 hours). If the head gasket is already blown, expect cylinder head removal, milling, and new gasket set (12-16 hours labor). Worst case: warped head requiring replacement or complete engine rebuild if overheated severely.

Estimated cost: $800-1,200 preventive cooling system overhaul; $2,500-4,000 head gasket job; $4,000-7,000 rebuild

Typical onset: 70,000-120,000 mi

Symptoms: transmission fluid leaking near radiator, slipping gears after warm-up, burnt ATF smell, sudden loss of all gears

Fix: The cooler lines rust through or fittings crack, dumping ATF. If you catch it early, it's just hose replacement (1-2 hours). If ATF runs dry, the 4-speed auto self-destructs within miles. Rebuild or used transmission swap is 8-12 hours labor.

Estimated cost: $150-300 lines only; $2,000-3,500 transmission rebuild; $1,200-2,000 used trans swap

Typical onset: 60,000-100,000 mi

Symptoms: clunk when shifting from park to drive, excessive engine rocking during throttle application, vibration through floor and shifter at idle, CV axle clicking from misalignment

Fix: The rubber mounts deteriorate badly with age and oil leaks. Replacing all mounts (front engine, rear trans, and subframe bushings) takes 4-6 hours. Ignoring them causes driveline misalignment that can kill CV joints and accelerate trans wear.

Estimated cost: $600-1,000

Symptoms: windows move slowly then stop mid-travel, clicking from door panel with no movement, intermittent operation requiring multiple switch presses, window drops into door

Fix: The regulators use plastic sliders that crack, and switches corrode internally. Each door is 1.5-2 hours labor. Not safety-critical but annoying and all four doors will eventually fail on a 30+ year old car.

Estimated cost: $250-400 per door

Typical onset: 90,000-140,000 mi

Symptoms: hard starting when hot, stumbling under acceleration, strong fuel smell in cabin or garage, stalling after warm-up

Fix: The in-tank fuel pump weakens, fuel filter clogs (often neglected — should be replaced every 30k), and injector o-rings harden causing vacuum leaks. Pump replacement is 2-3 hours, filter is 0.5 hour, injector seals are 3-4 hours if doing all five.

Estimated cost: $400-700 pump; $50-100 filter; $500-800 injector seals

Typical onset: 100,000+ mi

Symptoms: clunking over bumps, wandering at highway speeds, uneven tire wear on inside edges, steering wheel off-center after hitting bumps

Fix: The rubber bushings in the front control arms and subframe mounts turn to mush. In rust-belt cars, the subframe itself can corrode through the mounting points. Full front-end rebuild (all control arms, tie rods, subframe bushings) is 6-8 hours labor.

Estimated cost: $800-1,400