1976 BUICK CENTURY

Typical onset: 60,000-90,000 mi

Symptoms: slipping between gears especially 1st-2nd, delayed engagement when shifting to Drive, whining noise during acceleration, transmission overheating, no 2nd gear or stuck in 2nd

Fix: The TH200 behind the 231 V6 was undersized for even that modest engine. Clutch packs burn out, pump fails, and the aluminum case cracks under stress. Rebuild runs 8-12 hours labor but many shops recommend swapping to a TH350 from a donor car (requires different crossmember and possibly driveshaft shortening). Add 4-6 hours for conversion.

Estimated cost: $1,800-3,200

Symptoms: stumble or hesitation on acceleration, black smoke from exhaust, flooding and fuel smell in garage, high idle or stalling when warm, poor fuel economy suddenly drops further

Fix: The Rochester Quadrajet suffers from deteriorated accelerator pump cups, warped throttle shafts causing vacuum leaks, and clogged secondary air valve passages from old gas varnish. Complete rebuild kit plus ultrasonic cleaning takes 3-4 hours for someone experienced. Many owners convert to Edelbrock 1406 4-barrel for reliability.

Estimated cost: $400-750

Typical onset: 70,000-120,000 mi

Symptoms: heavy clunk when shifting into Drive or Reverse, visible engine movement when revving in Park, vibration through floor at idle, throttle linkage binding or sticking

Fix: Original rubber mounts deteriorate and the engine torques over, sometimes enough to contact the frame or stress transmission mounts. Replacing both engine mounts is 2-3 hours labor. Often discover transmission mount is also shot, add another hour. Should be done as a set.

Estimated cost: $350-600

Typical onset: 100,000-150,000 mi

Symptoms: heavy knocking from bottom of engine, metallic rattling that worsens with RPM, oil pressure drop especially at idle, metal shavings in oil filter

Fix: The 455 Stage I crank is strong but standard 455s used softer main journals that wear oval, especially if oil changes were neglected. Diagnosis requires dropping the pan; if bearing clearances exceed .004 the crank needs grinding and oversized bearings. Engine must come out—figure 16-22 hours for R&R, main bearing replacement, crank polishing or replacement if scored. Many owners opt for salvage 350 or 455 short block swap instead.

Estimated cost: $3,500-6,500

Symptoms: rough idle and stalling, Check Engine light if equipped, popping through carburetor on deceleration, dieseling after shutting off ignition, failing emissions testing in applicable states

Fix: The 1976 models have a rats nest of vacuum lines for EGR, AIR pump, EVAP canister, and various thermal switches. Rubber hardens and cracks, causing vacuum leaks that lean out the mixture. Diagnosis involves smoke testing or propane enrichment; repair is chasing down each cracked hose and failed check valve. Plan 2-4 hours of diagnostic and replacement labor. Many techs simplify the system by removing non-essential emissions equipment where legal.

Estimated cost: $250-500

Symptoms: engine cranks but won't start, starts then dies after 30 seconds, surging or cutting out under load, fuel smell but no delivery to carb

Fix: These cars often sit for years with old gas. Fuel turns to varnish, clogs the sock filter in the tank, gums up the mechanical fuel pump diaphragm, and plugs carburetor jets. Proper fix involves dropping the tank for cleaning/sealing (4-5 hours), new fuel pump, fuel filter, and carburetor rebuild. Shortcuts with in-line filters and additives rarely work long-term.

Estimated cost: $800-1,400