1990 BUICK CENTURY

Typical onset: 80,000-120,000 mi

Symptoms: white smoke from exhaust on startup, coolant loss with no visible leaks, overheating under load, milky oil on dipstick

Fix: Head gasket replacement requires removing intake/exhaust manifolds and resurfacing the head. Expect 6-8 labor hours. Often find warped head requiring machining or replacement. Smart to do timing chain and water pump while in there.

Estimated cost: $800-1,400

Typical onset: 70,000-110,000 mi

Symptoms: transmission fluid dripping from radiator area, pink fluid mixing with coolant in overflow, delayed engagement when cold, transmission overheating on highway

Fix: The internal transmission cooler in the radiator corrodes through, mixing coolant and ATF which destroys the transmission. Requires new radiator, flush entire cooling system, drain and refill transmission multiple times. If coolant got into trans, rebuild or replacement needed (8-12 hours). Preventive external cooler install is 2 hours.

Estimated cost: $400-700 (cooler only), $1,200-2,200 (with transmission rebuild)

Typical onset: 60,000-100,000 mi

Symptoms: loud clunk when shifting from park to drive, excessive vibration at idle in gear, visible engine movement when accelerating, difficulty shifting smoothly

Fix: The rubber transmission mount deteriorates and the powertrain shifts excessively, stressing shift linkage and axles. Replacement is straightforward with proper support, 1.5-2 hours. Check all three mounts while you're under there.

Estimated cost: $150-300

Typical onset: 70,000-130,000 mi

Symptoms: rough idle and stalling, coolant seepage at front of engine, vacuum leak codes or hunting idle, external coolant loss

Fix: The paper-style intake gaskets fail where they meet coolant passages. Not as catastrophic as head gasket but causes driveability issues. Remove upper intake, throttle body, and associated vacuum lines. 3-4 hours with proper cleaning of mating surfaces.

Estimated cost: $350-600

Symptoms: no-start condition, cranks but won't fire, intermittent stalling when hot, dies and restarts after cooling down, no fuel pump priming sound when key turned on

Fix: The fuel pump relay in the engine compartment fuse block fails from heat cycling. Common enough that experienced techs check it first on no-starts. Relay replacement is 0.2 hours, but diagnosis can add time if not familiar with the symptom.

Estimated cost: $30-80

Typical onset: 90,000-150,000 mi

Symptoms: intermittent no-start, sudden stalling while driving, dies when hot, starts when cool, no spark or injector pulse during crank

Fix: The crank sensor behind the harmonic balancer fails from heat. Requires removal of accessory belts and balancer with proper puller. 2-3 hours. Get the AC Delco part, aftermarket sensors fail repeatedly.

Estimated cost: $200-400

Typical onset: 80,000-120,000 mi

Symptoms: clunking noise over bumps from front end, steering doesn't return to center smoothly, popping sound when turning at low speed, visible rust or corrosion on strut towers

Fix: The strut mount bearings seize or the rubber isolators deteriorate. While you can replace just the mount, labor overlap with strut replacement means most do both together. Mounts alone are 2-3 hours for the pair.

Estimated cost: $250-450 (mounts only), $600-900 (with struts)