1970 CADILLAC FLEETWOOD SIXTY SPECIAL

Typical onset: 80,000-120,000 mi

Symptoms: Harsh 1-2 shift or slipping between gears, Delayed engagement when shifting into Drive, Burnt transmission fluid smell, Whining or grinding under acceleration

Fix: The THM400 behind the 472 takes a beating from the torque and weight. Expect a full rebuild with new clutches, bands, seals, and torque converter—plus external cooler line replacement since they rot. Figure 12-16 hours labor for removal, rebuild, and reinstall.

Estimated cost: $2,200-3,800

Typical onset: 100,000+ mi

Symptoms: Blue smoke on startup or acceleration, Burning through a quart every 500-800 miles, Fouled spark plugs on multiple cylinders, Loss of compression across the board

Fix: These engines weren't built tight by modern standards, and rings wear out or carbon-pack the grooves. A proper fix is pulling the engine for a ring job or full rebuild—pistons, bearings, hone, the works. Budget 24-30 hours for engine R&R plus machine work. Many owners just top off oil and drive it until something else breaks.

Estimated cost: $4,500-7,500

Typical onset: 120,000+ mi

Symptoms: Deep knocking from the bottom end at idle, Oil pressure dropping below 10 psi hot, Metallic debris in oil pan during changes, Catastrophic failure—engine seizes

Fix: The 472's long-stroke crank and heavy rotating assembly stress the mains, especially if oil changes were skipped. Once you've got knock, it's full teardown time—crank needs measuring, possibly turning or replacement, new bearings, line-boring if journals are damaged. This is 28-35 hours of labor plus machine shop time.

Estimated cost: $5,000-9,000

Symptoms: Transmission fluid puddling under the car near the radiator, Rapid fluid loss leading to slipping or no movement, Pink or red fluid mixing with coolant in the radiator

Fix: The steel cooler lines rust through after decades of road salt and weather exposure, or the rubber flex sections at the radiator harden and crack. Replacement is straightforward—new pre-bent lines or custom-bent stainless tubing take 2-3 hours. The killer is if you don't catch it fast and run the trans dry—then you're buying a rebuild.

Estimated cost: $250-500

Symptoms: Hard starting after sitting, even overnight, Raw fuel smell in the garage, Rough idle, black smoke, or stalling when cold, Fuel leaking from carb base or bowls

Fix: The Rochester Quadrajet on these sits for years between drives for many owners, leading to varnished jets, stuck floats, and leaking gaskets. A proper rebuild with new ethanol-resistant components runs 4-6 hours, plus fuel filter and line inspection. Some shops just slap on a reman carb and call it a day.

Estimated cost: $600-1,200

Symptoms: Clunking when shifting into gear or hitting the throttle, Excessive vibration through the cabin at idle, Engine visibly rocking side-to-side under load, Transmission tunnel contact noise over bumps

Fix: Rubber mounts turn to mush after 50+ years. The 472 is a heavy lump, so when the mounts go, you feel every ounce of it. Replacing all engine and transmission mounts takes about 4-5 hours with the right lift access. Not a hard job, but the engine weight makes it tedious without proper support.

Estimated cost: $400-700