1973 CADILLAC CALAIS

Typical onset: 80,000-120,000 mi or 40+ years of age

Symptoms: Delayed engagement into Drive or Reverse, Slipping between 1st and 2nd gear under moderate throttle, Pink or milky transmission fluid indicating coolant cross-contamination, Transmission running hot even in normal driving

Fix: The internal transmission oil cooler in the radiator corrodes and allows coolant into the ATF, destroying clutch packs and bands. Requires radiator replacement or external cooler addition (2 hrs), full transmission fluid flush (1.5 hrs), and often a transmission rebuild if contamination went unnoticed (12-16 hrs rebuild labor). Many shops now bypass the internal cooler entirely and install an external unit as preventive maintenance.

Estimated cost: $800-1,200 for cooler/radiator and flush; $2,800-4,500 if transmission rebuild needed

Typical onset: 120,000-180,000 mi or history of neglected oil changes

Symptoms: Oil pressure drops below 10 psi at hot idle, Deep knocking or rumbling from crankcase at startup, Metal flakes visible in oil filter media during changes, Lifter noise that doesn't quiet down after warm-up

Fix: The 472's main and rod bearings wear out, especially if oil changes were stretched or non-detergent oils used in the past. Proper repair means engine removal (8-10 hrs), full teardown, crank inspection/machining, and bearing replacement—essentially a short block rebuild (18-24 hrs total). Some owners limp along with higher-weight oil (20W-50), but this is borrowed time before catastrophic failure.

Estimated cost: $4,500-7,000 for proper short block rebuild with R&R

Symptoms: Rough idle or stalling when warm, Poor fuel economy—single digits in city driving, Hesitation or stumble off idle, Hard starting when engine is heat-soaked

Fix: The Rochester Quadrajet carburetor relies on dozens of vacuum lines and ports that harden and crack after 50 years. Vacuum leaks cause erratic idle, lean stumbles, and failed emissions equipment (EGR, AIR pump diverter valves). Diagnosis requires systematic vacuum circuit inspection (1.5 hrs), followed by carburetor rebuild or replacement (3-4 hrs), and vacuum line replacement throughout. Expect to replace every rubber vacuum hose under the hood.

Estimated cost: $600-1,200 including carburetor rebuild kit and all vacuum lines

Typical onset: 60,000+ mi or any 40+ year old example

Symptoms: Clunk when shifting from Park to Drive or Reverse, Vibration felt through floor at idle in gear, Excessive driveline movement visible when rocking car in gear with parking brake set, Increased cabin noise during acceleration

Fix: The rubber transmission mount disintegrates with age, allowing the heavy THM 400 to sag and create driveline misalignment. Replacement requires supporting the transmission (1.5-2 hrs labor). Often done alongside engine mounts if they show similar deterioration. This is a wear item that every survivor needs, but parts are still readily available and inexpensive.

Estimated cost: $180-320 for transmission mount; add $300-500 if doing engine mounts simultaneously

Symptoms: Hard starting after sitting overnight or longer, Engine dies after 10-15 minutes of driving as fuel pump heats up, Sputtering or surging at highway speeds, Fuel smell from evaporative system or leaking rubber lines

Fix: Cars that sat for years accumulate varnish in the tank, pickup sock, and fuel lines; original rubber fuel lines also deteriorate internally. Proper fix involves tank removal and cleaning or replacement (4-5 hrs), new fuel pump (2 hrs), inline filter, and replacement of all rubber fuel line from tank to carburetor (3-4 hrs for hard line with rubber sections). Fuel pump on these is mechanical, mounted low on engine—heat soak can cause vapor lock.

Estimated cost: $800-1,400 for complete fuel system refurbishment

Typical onset: 100,000-150,000 mi

Symptoms: Blue smoke on startup or deceleration, Oil consumption exceeding 1 quart per 500-800 miles, Fouled spark plugs on one or more cylinders, Low compression readings below 120 psi on multiple cylinders

Fix: The 472's large bore and long stroke make it susceptible to ring wear, especially if it idled extensively (taxi/livery use) or ran rich for years. Ring replacement alone requires heads-off work (14-16 hrs), but if cylinder bores are tapered or scored, a proper rebuild with boring and honing is necessary (20-26 hrs total). Some owners accept 1 qt/1000 mi consumption and just keep adding oil rather than rebuild.

Estimated cost: $3,200-5,500 for ring replacement with heads resurfaced; $5,000-8,000 for full rebuild with machine work