1962 CADILLAC COUPE DE VILLE

Typical onset: original units often have 80,000-150,000 mi or unknown history

Symptoms: Harsh or delayed engagement into Drive or Reverse, Slipping between gears, especially 2nd to 3rd, Burnt transmission fluid smell, dark or metallic fluid, External leaks from cooler lines or pan gasket

Fix: The 4-speed Hydra-Matic is notoriously heat-sensitive and many survivors have never had fresh fluid or cooler service. Full rebuild takes 12-16 hours; includes clutches, bands, seals, and mandatory oil cooler replacement or flushing. R&R transmission: 6-8 hours on its own due to weight and tight engine bay.

Estimated cost: $2,800-4,500

Typical onset: 100,000+ mi, or unknown maintenance history

Symptoms: Heavy knocking or rumbling from crankcase at idle, worsens with RPM, Low oil pressure at operating temperature (under 20 psi hot idle), Metallic debris in oil filter or pan, Excessive blowby or oil consumption

Fix: The 390 has a forged crank and will run forever with oil changes, but neglect kills the soft Babbitt bearings. Requires full teardown: R&R engine (8-10 hours), disassembly, crank inspection/turning, new bearings, reassembly. Often find cam wear and tired rings during inspection, so budget escalates. Short-block swap is faster if core available (10-12 hours total).

Estimated cost: $4,000-7,500

Typical onset: 80,000+ mi on original rings

Symptoms: Blue smoke on startup or steady at highway speed, Burning a quart of oil every 500-800 miles, Fouled spark plugs (oil-soaked), Poor compression readings across multiple cylinders

Fix: The 390's low-tension rings wear gradually; many engines were never rebuilt and now have .006"+ ring gaps. Proper fix is full teardown, hone or rebore cylinders, new pistons or rings, valve job. Total engine-out rebuild: 20-30 hours. A ring-only job (hone and re-ring in-chassis, if bore is good) is possible but risky on a 60-year-old block—expect 16-20 hours.

Estimated cost: $3,500-6,000

Symptoms: Hard starting when cold or after sitting, Rough idle, stalling at stop signs, Hesitation or flat spots on acceleration, Fuel leaking from carburetor base or accelerator pump

Fix: The Carter AFB 4-barrel carbs dry out and varnish quickly with ethanol fuel and sitting. Rebuild kits are available; plan 3-4 hours for disassembly, cleaning, kit install, and tuning. Often find rotted fuel filter (inline canister-style) and rust in the tank requiring drop and cleaning (add 4-6 hours). Fuel pump diaphragms also fail—mechanical pump replacement is 1 hour.

Estimated cost: $450-1,200

Symptoms: Loud clunk when shifting into Drive or Reverse, Excessive engine movement or shudder on acceleration, Visible cracks or separation in rubber mount pads, Driveline vibration at highway speeds

Fix: Original rubber mounts are long gone and aftermarket replacements vary in quality. Engine has 3 mounts (2 frame, 1 front); transmission has 1 rear. Plan 2-3 hours to replace all four with proper jacking and support. Mounts are cheap but labor access under this beast is tight.

Estimated cost: $350-650

Symptoms: Overheating in traffic or on hot days, Rusty or muddy-looking coolant, External leaks from freeze plugs, water pump, or lower hose connections, Heater performance loss

Fix: The 390 runs cool stock, but decades of mixed coolant and rust eat the brass radiator and core plugs. Radiator recore or replacement: 3-4 hours. Water pump (common leak point): 2-3 hours. Freeze plug replacement requires engine R&R or doing them in-chassis (front plugs only)—budget 6-10 hours if multiple rear plugs are weeping. Flush and correct coolant is mandatory preventive.

Estimated cost: $800-2,200