1967 PONTIAC BONNEVILLE

Symptoms: Clunk when shifting from Park to Drive or Reverse, Excessive vibration at idle, Transmission tailshaft visibly sagging, Driveline shudder under acceleration

Fix: Original rubber mounts deteriorate after 50+ years regardless of mileage. Replacement requires lifting the transmission slightly with a jack, typically 1.5-2 hours labor. Aftermarket polyurethane mounts last longer but transmit more vibration.

Estimated cost: $200-400

Symptoms: Transmission fluid dripping near radiator, Pink fluid residue on driveway, Transmission overheating on highway runs, Sudden loss of all transmission fluid

Fix: Steel cooler lines rust through at bends and fittings; internal radiator cooler can leak, mixing ATF and coolant which destroys the TH400. Line replacement is 2-3 hours, but if coolant contaminated the transmission, expect full rebuild. Always replace lines preventively during any cooling system work.

Estimated cost: $300-600 for lines only, $2,000-3,500 if transmission rebuild required

Typical onset: 120,000-180,000 mi

Symptoms: Blue smoke on startup that clears after warmup, Oil consumption exceeding 1 quart per 500 miles, Loss of compression on multiple cylinders, Blowby visible at PCV valve or oil filler cap

Fix: Original cast-iron rings wear against bores, especially if maintenance was deferred. A proper fix requires bore measurement and decision between re-ring with hone (25-30 hours) versus overbore with new pistons (30-35 hours). Many owners opt for a running used engine swap instead given age of other components.

Estimated cost: $3,500-5,500 for in-chassis rebuild, $2,500-4,000 for used engine swap

Typical onset: 100,000-150,000 mi

Symptoms: Oil pressure dropping below 10 psi at hot idle, Knocking or rumbling from lower engine that worsens with RPM, Metallic debris in oil filter or pan, Sudden catastrophic failure if ignored

Fix: Low oil pressure starts with worn oil pump but progresses to bearing failure if not addressed. Confirm with mechanical gauge before condemning bearings. Rod bearings can be replaced in-chassis (18-22 hours) but main bearings require full engine removal (35-40 hours). At this age and mileage, most shops recommend addressing all bearings, seals, and timing components simultaneously.

Estimated cost: $2,800-4,200 for rod bearings only, $4,500-6,500 for complete bearing overhaul with mains

Symptoms: Hard starting after sitting overnight or longer, Stumbling or hesitation on acceleration, Flooding or rich running conditions, Fuel smell from evaporated gas in float bowls

Fix: Modern ethanol fuel leaves varnish deposits in Rochester or Carter carburetors, especially in stored or infrequently-driven cars. A full carburetor rebuild kit with ultrasonic cleaning runs 3-5 hours. Inline fuel filter ($8-15) should be replaced annually, located between fuel pump and carburetor—often neglected but critical.

Estimated cost: $350-650 for carburetor rebuild, $50-100 for filter replacement

Typical onset: 80,000-140,000 mi

Symptoms: Clutch pedal hard to push or stays to floor (manual trans), Visible crankshaft end-play movement at harmonic balancer, Metallic scraping noise in sync with engine speed, Transmission input shaft misalignment

Fix: Thrust bearing (rear main bearing set component) wears from clutch riding or improper clutch adjustment, though rare on automatic cars. Requires full engine removal and crankshaft inspection for scoring. If crank is damaged, needs machining or replacement, adding significant cost and time (40+ hours total).

Estimated cost: $4,000-7,000 including crankshaft work