1975 CADILLAC SEVILLE

Typical onset: 60,000-100,000 mi

Symptoms: Excessive oil consumption (1 quart per 500-800 miles), Blue smoke on startup and acceleration, Loss of compression in multiple cylinders, Fouled spark plugs requiring frequent replacement

Fix: The Olds 350 in these cars suffers from inadequate cylinder wall hardening and weak ring seal. Full engine rebuild required including bore/hone, new pistons, rings, bearings. Many shops recommend short or long block replacement instead due to core condition. Expect 20-28 hours labor for R&R plus rebuild time, or 18-22 hours for complete engine swap.

Estimated cost: $3,500-6,500

Typical onset: 50,000-90,000 mi

Symptoms: Transmission fluid leaking at radiator connections, Pink/red fluid pooling under front of vehicle, Low transmission fluid level, Slipping or delayed engagement if fluid loss is severe

Fix: Steel cooler lines rust through at bends and fittings, especially where they connect to the radiator. Both lines typically need replacement, not just the leaking one. Includes new rubber hoses at radiator end. If caught early, transmission survives; if run low, expect internal damage requiring rebuild. Line replacement: 2-3 hours labor.

Estimated cost: $250-450

Typical onset: 80,000-120,000 mi

Symptoms: Deep knocking sound from lower engine, especially when cold, Oil pressure dropping below 10 PSI at idle when warm, Metallic debris in oil filter during changes, Vibration through entire drivetrain

Fix: The Olds 350's crankshaft journals wear excessively, particularly if oil changes were neglected. Requires engine removal, complete teardown, crankshaft removal for machining or replacement, new main and rod bearings, line boring of mains if worn. This is a full rebuild scenario. 25-35 hours total labor including R&R and machine work downtime.

Estimated cost: $4,000-7,000

Symptoms: Hard starting after sitting overnight, Stumbling and hesitation during acceleration, Stalling when coming to stops, Fuel smell in cabin or garage

Fix: Rubber fuel lines, filter housings, and carb components deteriorate after 45+ years. Fuel filters clog rapidly from tank sediment. Requires systematic replacement of all rubber fuel lines, inline filter, fuel pump (often mechanical pump failure), and carburetor rebuild. Fuel tank cleaning/sealing often needed. 6-10 hours labor depending on scope.

Estimated cost: $800-1,800

Typical onset: varies

Symptoms: Clunking when shifting from Park to Drive or Reverse, Excessive drivetrain movement visible during acceleration, Vibration at idle in gear, Transmission tail housing sitting low

Fix: The rubber transmission mount deteriorates and collapses, allowing excessive drivetrain movement. Straightforward replacement but requires supporting transmission with jack. 1.5-2 hours labor. Often discovered during other transmission work.

Estimated cost: $150-300

Symptoms: Intermittent no-start conditions, Rough idle and poor fuel economy, Check engine light issues if upgraded to later system, Fuel pressure inconsistencies

Fix: Some owners retrofit Cadillac's 1976+ EFI system or modern aftermarket EFI. When these conversions are done poorly or age out, diagnosis becomes nightmare due to mix of vintage and modern components. Requires electrical troubleshooting skills and often component-by-component testing. 4-12 hours depending on issue complexity.

Estimated cost: $500-2,000