1970 CADILLAC FLEETWOOD

Typical onset: 100,000-150,000 mi

Symptoms: deep knocking sound from lower engine, metallic grinding on startup, oil pressure drops significantly, metal shavings in oil filter

Fix: Full engine teardown required. Crankshaft typically needs machining or replacement, main bearings replaced, plus all gaskets and seals. Expect 18-24 labor hours for removal, machining, reassembly, and reinstallation. If crank is damaged beyond repair, you're into short block territory.

Estimated cost: $3,500-6,500

Typical onset: 80,000-120,000 mi

Symptoms: excessive blue smoke on startup and acceleration, high oil consumption (quart per 500-800 miles), fouled spark plugs, poor compression readings across multiple cylinders

Fix: Rings alone can be done with engine in-car on a lift if cylinders aren't scored, but most shops pull the engine for proper honing and inspection. Budget 20-28 hours for pull, hone, new rings, bearings, gaskets, and reinstall. If cylinder walls are damaged, you're boring oversize or sleeving.

Estimated cost: $2,800-5,200

Typical onset: 60,000-100,000 mi

Symptoms: transmission fluid in radiator or coolant in transmission, milky pink fluid on dipstick, erratic shifting or slipping, overheating transmission

Fix: The internal cooler in the radiator fails and cross-contaminates fluids, destroying the transmission if not caught early. Requires radiator replacement or external cooler bypass, complete transmission flush or rebuild if contaminated, and all new fluid. If caught late, full TH400 rebuild adds 12-16 hours. Early catch is 4-6 hours for radiator and flush.

Estimated cost: $800-3,800

Symptoms: clunk when shifting into drive or reverse, excessive vibration at idle in gear, visible sagging of transmission tailshaft, harsh engagement

Fix: Rubber mounts age-harden and crack after 50+ years regardless of mileage. Replacement requires supporting the transmission and unbolting the crossmember. Straightforward 2-3 hour job, but often discovered during other work.

Estimated cost: $250-450

Symptoms: hard starting when hot, rough idle and stalling, fuel smell or visible leaks from carburetor, poor fuel economy even for a 5,000-lb car

Fix: The Rochester Quadrajet carburetors develop vacuum leaks, stuck floats, and accelerator pump failures after decades. Rebuilds run 4-6 hours including removal, kit installation, and tuning. Fuel filters clog from tank sediment—always replace when diagnosing fuel starvation. Fuel pumps fail too but are cheap mechanical units.

Estimated cost: $450-900

Typical onset: 70,000-110,000 mi

Symptoms: running hot in traffic or summer weather, coolant loss with no visible leaks, water pump bearing noise, heater performance drops

Fix: Original radiators corrode internally and lose capacity. Water pumps fail around 80k-100k. Thermostats stick. The 472 runs hot by design and needs proper coolant flow. Budget 3-4 hours for radiator replacement, 2-3 for water pump. Expect to do both if one fails—they're all 50+ years old now.

Estimated cost: $600-1,400