1991 FORD THUNDERBIRD

Typical onset: 80,000-140,000 mi

Symptoms: white smoke from exhaust, coolant loss with no visible leaks, milky oil on dipstick, overheating under load

Fix: Requires both head gaskets, resurfacing both heads (they warp), new head bolts, and thorough cooling system flush. Plan 12-16 hours labor. Often discover intake manifold gasket issues during teardown, add 2 hours.

Estimated cost: $1,800-2,800

Typical onset: 60,000-120,000 mi

Symptoms: transmission fluid in coolant (strawberry milkshake in overflow), transmission slipping after brief drives, pink residue in radiator, sudden transmission failure after overheat

Fix: The steel cooler lines rust through where they connect to radiator, mixing fluids destroys transmission. Must replace radiator, all cooler lines, flush entire cooling system, rebuild or replace transmission if contamination occurred. External auxiliary cooler highly recommended. 8-10 hours if just lines/radiator, 18-24 hours if transmission damaged.

Estimated cost: $800-1,200 (caught early), $2,500-4,000 (with transmission damage)

Typical onset: 90,000-150,000 mi

Symptoms: no overdrive engagement on highway, 3-4 shift flare or slip, harsh 2-3 shifts, Check Engine light with transmission codes

Fix: Overdrive servo bore wears, causing loss of 4th gear. Requires transmission removal, teardown, bore repair with sleeve kit, new clutches and bands. 10-14 hours labor for R&R and rebuild.

Estimated cost: $1,600-2,400

Typical onset: 70,000-110,000 mi

Symptoms: severe vibration at idle, serpentine belt walking off pulleys, visible wobble at crankshaft pulley, squealing belts that won't stay aligned

Fix: Rubber ring between hub and outer pulley deteriorates, outer ring separates. Replace balancer (not rebuild), check for crank snout damage. 2-3 hours labor if caught early, 6-8 hours if crank needs machining.

Estimated cost: $350-600 (balancer only), $1,200-1,800 (with crank repair)

Symptoms: no-start when engine hot, starts fine cold, stalling after 20-30 minutes driving, intermittent loss of spark, stranded in parking lots after shopping

Fix: TFI (Thick Film Ignition) module on distributor fails when heat-soaked. Dies, cools down, works again. Replace module and apply dielectric grease. 0.5-1 hour labor, but diagnosis eats time because it's intermittent.

Estimated cost: $150-280

Typical onset: 75,000-120,000 mi

Symptoms: clunking over bumps, wandering steering, inner tire edge wear, looseness felt in wheel at 10-2 position

Fix: MN12 platform eats lower ball joints due to weight and geometry. Requires replacement of lower control arm assembly (ball joint not serviceable separately on many). 2-3 hours per side, alignment mandatory after.

Estimated cost: $400-700 both sides plus alignment

Typical onset: 100,000-160,000 mi

Symptoms: engine cranks but won't start, loss of power climbing hills, sputtering at highway speeds, whining noise from rear of car

Fix: In-tank pump typical of era. Must drop fuel tank (especially tedious on Super Coupe with dual exhaust). Replace pump, strainer, and rubber fuel lines while tank is down. 3-4 hours labor.

Estimated cost: $450-750