1956 CADILLAC FLEETWOOD SIXTY SPECIAL

Typical onset: 80,000-150,000 mi

Symptoms: Heavy knocking on cold start that may fade when warm, Low oil pressure below 15 psi at idle when hot, Metallic rattling during acceleration, Visible metal particles in oil filter

Fix: Main and rod bearings are typically worn beyond spec on surviving examples. Most need a full teardown with crankshaft inspection and possible machining (0.010-0.020 under). Budget 40-50 hours for proper bottom-end rebuild with machine work. Many shops recommend full engine rebuild at this point given age and parts availability challenges.

Estimated cost: $4,500-8,500

Typical onset: 70,000-120,000 mi

Symptoms: Blue smoke on startup that clears after warmup, Excessive crankcase pressure/oil breather blowby, Oil consumption exceeding 1 quart per 500 miles, Poor compression readings below 100 psi on multiple cylinders

Fix: Ring wear and cylinder glazing common on engines that sat for years or were babied. Requires bore inspection—many need 0.030-0.060 overbore and new pistons. In-chassis ring job rarely worth it due to labor overlap with full rebuild. Figure 45-55 hours for proper overhaul with bore work and deck surfacing.

Estimated cost: $5,000-9,000

Symptoms: Coolant mixing into oil (milky dipstick), Overheating in traffic with no external leaks, Cross-cylinder compression leakage on adjacent cylinders, White exhaust smoke with sweet smell

Fix: Often caused by overheating events or improper previous repairs. Both heads should come off for inspection and milling (typical 0.008-0.015 warpage). Expect 18-24 hours labor. This is when you discover cracked heads or additional problems, so budget conservatively. Parts availability for correct gaskets can be challenging.

Estimated cost: $2,200-3,800

Typical onset: 60,000-100,000 mi

Symptoms: Delayed engagement into drive (3+ seconds), Slipping between 2nd and 3rd gear under load, Burnt transmission fluid smell, Shuddering during kickdown

Fix: The cast-iron Hydra-Matic is robust but clutch packs and bands wear. Fluid cross-contamination through cooler ruins rebuilds—always replace cooler and flush lines. Full rebuild takes 16-22 hours including R&R. Specialist transmission shops preferable; parts availability moderate through specialty suppliers.

Estimated cost: $2,800-4,500

Symptoms: Excessive engine rocking during acceleration/deceleration, Clunking when shifting into gear, Vibration through floorboards at idle, Visible cracking or separation of rubber mount material

Fix: Original rubber mounts are 70 years old and universally deteriorated. Replacement mounts may require fabrication or NOS parts hunting. Engine mounts need engine support during replacement—3-5 hours. Transmission mount is easier at 1-2 hours. Upgrading all mounts during engine-out work is standard practice.

Estimated cost: $400-900

Symptoms: Hard starting after sitting overnight, Rough idle with occasional stalling, Hesitation during acceleration, Fuel smell from evaporation

Fix: Carter 4-barrel carburetors gum up badly if car sits. Full rebuild with ultrasonic cleaning takes 6-8 hours including removal, tuning, and re-jetting. Tank and fuel lines typically need cleaning/replacement on survivors. Inline filter helps but address root cause. Modern ethanol fuel accelerates deterioration.

Estimated cost: $600-1,200