1965 PONTIAC BONNEVILLE

Typical onset: 70,000-110,000 mi

Symptoms: Slipping between gears, especially 1-2 shift, Delayed engagement when shifting into Drive or Reverse, Burnt transmission fluid smell, dark or metallic fluid, Hard or erratic shifts under throttle

Fix: Full rebuild required in most cases—clutch packs, bands, seals, and torque converter. Expect 12-16 hours labor for removal, rebuild, and reinstall. The two-speed Jetaway is simpler but parts availability is declining; THM400 conversions are common.

Estimated cost: $2,200-3,800

Typical onset: 60,000-120,000 mi

Symptoms: Transmission fluid puddles under front of car, Low fluid level causing slipping or delayed shifts, Visible corrosion or seepage at cooler line fittings on radiator, Sudden loss of Drive after highway use if line ruptures

Fix: Replace both steel cooler lines and fittings; original lines rust through at bends and radiator connections. Also inspect internal radiator cooler for cross-contamination if coolant looks pink/milky. 2-3 hours labor for lines, add 4-6 hours if radiator needs R&R for internal cooler repair.

Estimated cost: $350-900

Typical onset: 90,000-150,000 mi

Symptoms: Heavy knocking from crankcase, worsens with RPM, Low oil pressure at idle (under 10 psi hot), Metallic debris in oil pan or filter, Catastrophic failure: thrown rod, cracked block

Fix: Caused by deferred oil changes, overheating, or running low on oil. Requires crankshaft removal, turning or replacement, and new main/rod bearings. If crank is damaged beyond .030" undersize, replacement cranks are scarce. 20-28 hours for teardown, machine work, and reassembly. Many owners opt for complete long-block replacement or crate engine.

Estimated cost: $4,500-7,500

Typical onset: 80,000-130,000 mi

Symptoms: Blue smoke on startup or deceleration, Consuming 1+ quart of oil per 500-800 miles, Fouled spark plugs, misfires on cold start, Low compression readings (under 120 psi)

Fix: Ring job requires engine removal, honing cylinders, new rings, and often new pistons if bores are worn beyond .030" oversize. Check valve seals first—if they're the culprit, it's a 6-8 hour head-off job. Full ring/piston job is 18-24 hours including R&R. Many choose to do full rebuild at this point.

Estimated cost: $2,800-5,000

Symptoms: Clunking when shifting from Park to Drive or Reverse, Excessive vibration at idle in gear, Visible sagging or cracking of rubber mount, Driveline shudder on acceleration

Fix: Original rubber mounts harden and crack over decades, even on low-mileage survivors. Replacement is straightforward: support transmission with jack, unbolt old mount, install new. 1-1.5 hours labor. Aftermarket polyurethane mounts available for firmer feel.

Estimated cost: $150-300

Symptoms: Hard starting after sitting, especially when warm, Rough idle, stumbling on acceleration, Flooding, fuel smell in cabin or garage, Stalling at stop lights

Fix: Rochester or Carter carburetors gum up from ethanol fuel if car sits. Fuel filters (inline and in-carb) clog with varnish. Start with fresh fuel, new filter, and carb cleaning (3-4 hours). If diaphragms or accelerator pump failed, rebuild kit is $80-150 and adds 2 hours. Tank may need drop and cleaning if sediment is severe (add 4-6 hours).

Estimated cost: $400-1,200