1955 CADILLAC FLEETWOOD 75

Typical onset: 80,000-150,000 mi original, or unknown history

Symptoms: Heavy knocking from crankcase especially under load or cold start, Oil pressure drops below 10 psi at idle when warm, Metallic debris in oil pan or filter, Visible rod or main bearing material on drain plug magnet

Fix: Complete lower-end teardown requiring crankshaft removal, inspection, and typically a 0.010" or 0.020" undersize grind, new main and rod bearings, and full gasket set. Engine-out job requiring 18-24 labor hours including R&R, plus machine shop time for crank work. If crank is too far gone, sourcing NOS or used replacement adds weeks and cost.

Estimated cost: $4,500-7,500

Typical onset: 100,000+ mi or cars with prolonged storage and dry starts

Symptoms: Lumpy idle with one or more dead cylinders, Valve train ticking or clatter that doesn't quiet with warm-up, Loss of power and poor throttle response, Abnormal valve lash measurements on multiple cylinders

Fix: Camshaft replacement requires engine removal or at minimum front-end disassembly (radiator, timing cover, harmonic balancer). Expect 14-18 hours labor. Flat-tappet cams sensitive to oil quality and break-in; must replace lifters simultaneously and use ZDDP-fortified break-in oil.

Estimated cost: $3,200-5,000

Typical onset: 90,000+ mi or cars with irregular oil service

Symptoms: Heavy blue smoke on startup and during deceleration, Excessive crankcase pressure venting from oil filler or road draft tube, Oil consumption exceeding 1 quart per 500 miles, Poor compression readings below 100 psi on multiple cylinders

Fix: Full engine rebuild with cylinder honing or boring if taper exceeds 0.006", new piston ring sets, and rod reconditioning. If pistons are scored or skirts worn, factor in NOS piston sets which are scarce. Plan 20-28 hours for complete teardown, machine work coordination, and reassembly with engine out.

Estimated cost: $5,500-9,000

Symptoms: Severe clunking when shifting from Park to Drive or Reverse, Visible transmission sag or misalignment when inspected from below, Driveline vibration at highway speeds, Transmission tailshaft visibly low or contacting crossmember

Fix: Replace transmission mount and inspect crossmember for cracks from chronic stress. Original rubber mounts are NLA; polyurethane aftermarket replacements common but transmit more vibration. Requires transmission support and crossmember removal, 2-3 hours labor.

Estimated cost: $350-600

Symptoms: Hard starting or long cranking before engine fires, Surging or hesitation under acceleration, Engine stumbling at idle after sitting overnight, Fuel starvation at higher speeds or grades

Fix: Systematic fuel system cleaning: drop and boil out tank, replace fuel lines if cracked, new fuel pump and filter, carburetor disassembly and ultrasonic cleaning with rebuild kit. Ethanol fuel accelerates deterioration on cars in intermittent use. Total 6-9 hours including tank service.

Estimated cost: $800-1,400

Typical onset: 100,000+ mi

Symptoms: Blue smoke puff on startup that clears after 30 seconds, Oil consumption moderate (1 qt per 1,000 miles), Visible valve stem side-play with rocker arms removed, Carbon buildup on intake valve stems visible through ports

Fix: Cylinder head removal for valve guide replacement or knurling, plus new valve stem seals. Heads should be pressure-tested and milled for flatness. Can often do without pulling engine. 12-16 hours labor plus machine shop for guide work and valve job.

Estimated cost: $2,800-4,200