1984 BUICK CENTURY

Typical onset: 80,000-120,000 mi

Symptoms: Slipping between gears, especially 1st to 2nd, Delayed engagement when shifting to drive or reverse, Burnt transmission fluid smell and dark/contaminated fluid, Complete loss of forward gears while reverse still works

Fix: The THM 125C (also called Turbo-Hydramatic 125) is notoriously weak in these A-bodies. Rebuild requires 8-12 hours labor including R&R. Many shops recommend replacing worn transmission mounts and cooler lines at same time since you're already in there. External cooler highly recommended on rebuild.

Estimated cost: $1,400-2,200

Typical onset: 60,000-90,000 mi

Symptoms: White smoke from exhaust indicating coolant intrusion, Overheating with no external leaks, Loss of compression in multiple cylinders, Cracked cylinder heads or blown head gaskets, Seized or spun main bearings

Fix: The Oldsmobile 5.7L diesel's little brother is equally troublesome. Head gaskets fail due to inadequate head bolt torque and weak block design. Most common fix is engine replacement or conversion to gas V6, as rebuilds often fail again. Complete engine swap runs 16-24 hours including all ancillaries.

Estimated cost: $2,800-4,500

Typical onset: 100,000-150,000 mi

Symptoms: Loud ticking or tapping noise from valve train, especially cold start, Loss of power and rough idle, Check engine light with low oil pressure codes, Metallic rattling that doesn't quiet down after warmup

Fix: The 2.5L Iron Duke is generally bulletproof, but hydraulic lifters fail and camshaft lobes wear when oil changes are neglected. Replacing all lifters and inspecting cam requires 6-8 hours with intake manifold removal. Often discover worn cam requiring full top-end rebuild.

Estimated cost: $800-1,400

Typical onset: 70,000-110,000 mi

Symptoms: Coolant puddles under engine, often passenger side, Slow coolant loss requiring frequent top-offs, Overheating under load, Visible coolant weeping from side of engine block

Fix: Midwest cars especially see corroded freeze plugs. Rear plugs require transmission removal or pulling engine. Most shops quote engine-out for complete freeze plug replacement - 10-14 hours. Half-measure of replacing accessible plugs only buys you a year or two before rears go.

Estimated cost: $900-1,600

Symptoms: Transmission fluid in coolant (strawberry milkshake appearance), Coolant in transmission pan, Sudden transmission failure after overheating, Leaking fluid from radiator area or cooler lines

Fix: The cooler built into the radiator can fail internally, mixing coolant and ATF which destroys the transmission. Requires radiator replacement, transmission flush or rebuild if contamination occurred, and all cooler lines. If caught early before mixing, 4-6 hours. If transmission contaminated, add rebuild time.

Estimated cost: $600-1,000 (early catch), $2,200-3,500 (with trans damage)

Symptoms: Visible rust perforation behind rear wheels, Rear suspension mounting points crumbling, Fuel tank strap corrosion, Soft or rotted floor pans under carpet, Clunking from rear on bumps as subframe flexes

Fix: Salt-belt cars develop catastrophic rust in rear torque box, subframe rails, and floor pans. This is structural and expensive - requires frame repair or sectioning by experienced body shop. 20-40 hours depending on extent. Many cars are totaled rather than repaired.

Estimated cost: $2,500-5,000

Symptoms: Hard starting when cold or hot, Stalling at idle or when coming to stop, Black smoke and poor fuel economy, Rough idle and hesitation on acceleration

Fix: Rochester carburetors on early '84s require periodic rebuild due to degraded gaskets, worn throttle shafts, and stuck choke mechanisms. Full rebuild takes 3-4 hours if done properly with new accelerator pump, float, and all internal parts. Many shops now replace with remanufactured units.

Estimated cost: $350-650