1974 CADILLAC DEVILLE

Typical onset: 80,000-140,000 mi

Symptoms: Pink or red transmission fluid in radiator or coolant reservoir, Transmission slipping or delayed engagement after mixing fluids, Engine overheating from ATF contaminating coolant, Complete transmission failure if not caught early

Fix: Replace transmission cooler (often integrated into radiator), flush both cooling system and transmission completely, replace radiator if cooler is internal. If ATF contaminated coolant system, expect 6-8 hours labor minimum including system flushes. If transmission internals damaged from coolant intrusion, add full rebuild.

Estimated cost: $800-1,200 for cooler/radiator and flushes; $2,500-4,000 if transmission needs rebuild

Symptoms: Hard starting when cold or hot, Black smoke and terrible fuel economy (worse than the already-bad 8-10 mpg), Hesitation, stumbling, or stalling at idle, Leaking fuel from accelerator pump or float bowl

Fix: The Q-jet is rebuildable but 50-year-old examples usually have warped throttle shafts, worn bushings, and cracked castings. Quality rebuild with updated seals and proper jetting takes 3-4 hours. Many owners swap to Edelbrock 1406 or similar for reliability.

Estimated cost: $400-700 for professional rebuild; $350-450 for Edelbrock swap

Typical onset: 100,000-150,000 mi

Symptoms: Loud ticking or tapping from valve train that doesn't quiet with oil pressure, Loss of power and rough idle, Metal shavings in oil or on magnetic drain plug, One or more cylinders misfiring consistently

Fix: The 472 used a soft flat-tappet cam that wears with wrong oil (need high ZDDP) or neglect. Cam replacement requires intake manifold removal, timing cover work, and often new lifters. Experienced tech needs 10-14 hours. If cam debris damaged bearings, you're looking at full teardown.

Estimated cost: $1,800-3,200 for cam/lifter job; $4,500-7,000 if bearings damaged requiring short block work

Typical onset: 120,000-180,000 mi

Symptoms: Blue smoke on startup or acceleration, Excessive oil consumption (more than 1 qt per 500 miles), Low compression across multiple cylinders, Blowby visible at PCV valve or oil fill cap

Fix: The 472 runs loose tolerances and rings wear, especially if overheated. Proper ring job requires honing cylinders, new rings, often pistons if worn. If cylinders need boring (.030 over common), you're at 25-30 hours labor for complete teardown, machine work, and reassembly.

Estimated cost: $3,500-5,500 for ring job with hone; $5,000-8,000 for bore and pistons

Typical onset: 60,000-100,000 mi

Symptoms: Clunk when shifting from park to drive or reverse, Excessive vibration at idle in gear, Visible transmission sag when inspecting from below, Harsh engagement into gear

Fix: The rubber transmission mount deteriorates from heat and age. Replacement is straightforward—support transmission, unbolt old mount, install new. Takes 1-2 hours. Cheap fix that makes a big difference in drivability.

Estimated cost: $150-300

Symptoms: White smoke from exhaust (coolant burning), Coolant loss with no external leaks, Oil that looks like chocolate milk, Overheating and bubbling in overflow tank

Fix: Usually follows a cooling system failure (bad thermostat, clogged radiator, failed water pump). Both heads need to come off, surfaces machined flat, and new gaskets installed. With manifold removal and cleanup, expect 16-20 hours. Check for warped heads—common on overheated 472s.

Estimated cost: $2,200-3,800 including machine work