1988 CADILLAC FLEETWOOD

Typical onset: 60,000-120,000 mi

Symptoms: Excessive oil consumption (quart every 500-1000 miles), White or blue smoke on startup, Loss of compression, Coolant in oil or oil in coolant, Knocking or ticking that worsens with heat

Fix: The aluminum block with cast-iron cylinder liners suffers liner movement and head gasket failures due to inadequate block strength. Full engine rebuild with updated components runs 40-50 hours, or long block replacement at 25-35 hours. Many owners opt for Oldsmobile 307 or Chevy 350 swaps instead.

Estimated cost: $4,500-8,000

Typical onset: 80,000-150,000 mi

Symptoms: Transmission fluid leak at radiator connections, Pink milky transmission fluid (coolant contamination), Delayed or harsh shifting, Transmission overheating, Complete transmission failure if coolant mixes

Fix: Steel cooler lines rust through where they connect to the radiator, or internal radiator cooler fails allowing coolant/ATF mixing. Requires line replacement (2-3 hours) and often full transmission flush. If contamination occurred, transmission rebuild is mandatory (15-20 hours total).

Estimated cost: $300-500 for lines only, $2,000-3,500 if transmission damaged

Typical onset: 70,000-130,000 mi

Symptoms: Loud ticking or clattering from engine, especially cold, Ticking that persists after warmup, Rough idle, Loss of power, Check engine light for misfire

Fix: The HT-4100's lifters are notorious for failing, often from inadequate oil pressure or contaminated oil. Replacement requires intake manifold removal and careful clearance checking. All 16 lifters typically replaced at once (10-14 hours). Often done during head gasket or rebuild work.

Estimated cost: $1,200-2,000

Typical onset: 80,000-140,000 mi

Symptoms: Clunk when shifting from Park to Drive or Reverse, Vibration at idle in gear, Excessive drivetrain movement felt through chassis, Visible sagging of transmission tailshaft

Fix: Rubber transmission mount separates or collapses from age and fluid contamination. Straightforward replacement accessible from underneath (1.5-2 hours). Often done with other transmission work.

Estimated cost: $200-350

Symptoms: Hard starting after sitting, Stalling at idle or low speed, Hesitation under acceleration, Surging at cruise, Won't start after sitting overnight

Fix: TBI injection system accumulates varnish, and in-tank fuel pumps can fail from ethanol fuel in aged systems. Fuel filter (0.5 hours) should be first step. Injector cleaning and throttle body service adds 2-3 hours. Pump replacement requires tank drop (4-6 hours).

Estimated cost: $150-250 for filter/cleaning, $600-900 for pump

Typical onset: 50,000-100,000 mi

Symptoms: Coolant loss with no visible leaks, White exhaust smoke, Overheating, Rough running and misfire, Oil in coolant reservoir or coolant in oil

Fix: The HT-4100's aluminum heads expand differently than the block, and head bolt threads in the aluminum block strip or pull out. Head gasket job requires both sides (18-24 hours), often needs thread repair inserts (Heli-Coil), and frequently reveals other engine damage requiring full rebuild.

Estimated cost: $2,500-4,000 if block is sound