1981 CADILLAC SEVILLE

Typical onset: 50,000-90,000 mi

Symptoms: White smoke from exhaust indicating coolant intrusion, Sudden loss of compression, Cracked cylinder heads, Spun main bearings, Hydrolocked cylinders from head gasket failure

Fix: These diesel engines are fundamentally flawed with inadequate head bolt torque, weak head gaskets, and blocks not designed for diesel compression. Complete engine replacement or rebuild required, typically 35-45 labor hours for removal, rebuild, and reinstall. Most shops refuse these jobs or recommend gas conversion.

Estimated cost: $6,500-12,000

Typical onset: 80,000-130,000 mi

Symptoms: Slipping between gears especially 1-2 shift, Burnt transmission fluid smell, Delayed engagement when cold, No reverse or erratic reverse operation, Metal shavings in pan during service

Fix: The THM400 behind both engines suffers from inadequate cooling and worn clutch packs. Transmission cooler often clogs or leaks. Full rebuild requires 12-16 hours, always replace cooler and lines during rebuild. Recommend auxiliary cooler installation.

Estimated cost: $2,800-4,200

Symptoms: No start condition with cranking, Intermittent stalling when warm, Engine dies and won't restart until cool, Check engine light with no stored codes, Fuel pump runs but no injector pulse

Fix: The DFI computer module fails due to heat and age-related capacitor breakdown. Replacement modules are NLA from GM; requires used unit or aftermarket replacement. Diagnosis 2-3 hours, replacement 1 hour. Some specialists offer module rebuilding service.

Estimated cost: $800-1,500

Typical onset: 60,000-100,000 mi

Symptoms: Hard starting especially cold, Loss of power under load, Black smoke on acceleration, Rough idle and misfiring, Fuel in crankcase oil indicating injector leak

Fix: Stanadyne injection pump wears internally, injectors leak back into cylinders. Water contamination common in these systems accelerates wear. Injection pump replacement 8-10 hours, all injectors should be replaced simultaneously. Fuel system must be cleaned thoroughly.

Estimated cost: $2,500-4,000

Typical onset: 70,000-120,000 mi

Symptoms: Oil puddles under rear of engine, Oil coating transmission bellhousing, Low oil level between changes, Oil dripping from oil pan rail onto crossmember

Fix: Both engines develop rear main seal leaks and oil pan gasket failures. Rear main requires transmission removal, 8-10 hours labor. Oil pan requires subframe drop or engine lift on Seville due to tight clearances, 6-8 hours. Do both simultaneously if transmission is already out.

Estimated cost: $1,200-2,200

Symptoms: No response from climate control buttons, Blower stuck on high or won't run, Temperature blend door not responding, Display blank or showing error codes, AC compressor won't engage

Fix: The electronic climate control head and programmer assembly fail from solder joint cracks and component degradation. Replacement units scarce; many owners convert to manual controls. Diagnosis and replacement 3-4 hours if parts available.

Estimated cost: $600-1,200

Typical onset: 60,000-90,000 mi

Symptoms: Wandering steering requiring constant correction, Clunking over bumps from front end, Loose steering feel with excessive play, Uneven tire wear on front, Steering wheel off-center after hitting bumps

Fix: The Seville's heavy weight and soft suspension geometry accelerate idler arm bushing wear. Center link and tie rod ends wear simultaneously. Replace entire steering linkage as a system, alignment required. 4-5 hours for complete front end rebuild including alignment.

Estimated cost: $800-1,400