1979 BUICK RIVIERA

Typical onset: 70,000-110,000 mi

Symptoms: Milky or pink transmission fluid indicating coolant intrusion, Transmission slipping or delayed engagement after cooler rupture, Overheating transmission or engine coolant loss, Strawberry milkshake appearance in radiator overflow

Fix: The internal transmission cooler in the radiator fails, allowing coolant and ATF to mix. This destroys the transmission if not caught early. Requires radiator replacement, complete transmission flush or rebuild if contamination occurred, and all cooler lines. 8-16 hours labor depending on transmission damage.

Estimated cost: $1,200-3,800

Typical onset: 90,000-140,000 mi

Symptoms: Slipping between gears, especially 2nd to 3rd, No reverse or delayed reverse engagement, Whining or grinding noise in gear, Burned ATF smell and dark fluid color

Fix: The TH325 used behind the V6 and small V8s is weak and prone to clutch pack and sun shell failures. Later TH200-4R overdrive units have similar issues plus governor problems. Full rebuild with hardened components recommended. 10-14 hours for R&R and rebuild.

Estimated cost: $2,200-3,500

Typical onset: 50,000-90,000 mi

Symptoms: Excessive white or blue smoke on startup, Severe knocking or rattling from engine block, Sudden loss of power and loud bang indicating crank or rod failure, Coolant mixing with oil or vice versa from cracked block

Fix: GM's 350 diesel used a gasoline block with insufficient strength for diesel compression. Head bolt failures, cracked blocks, and spun main bearings are epidemic. Only fix is replacement with gasoline V8 or another diesel long block. 18-24 hours for full swap.

Estimated cost: $4,500-7,500

Typical onset: 100,000-150,000 mi

Symptoms: Blue smoke from exhaust on acceleration or deceleration, Burning through a quart of oil every 500-800 miles, Fouled spark plugs on cylinders 2, 4, or 6, Poor compression readings below 100 psi on affected cylinders

Fix: The 231 V6 suffers from ring wear and cylinder glazing, especially if maintenance was deferred. Requires cylinder honing, new rings, and usually valve work while apart. Short block replacement if cylinder wear exceeds spec. 14-18 hours for full teardown and re-ring.

Estimated cost: $2,000-3,200

Symptoms: Rough idle and stalling when warm, Black smoke and flooding from stuck mixture control solenoid, Check engine light with codes 32, 34, or 44, Surging at highway speeds or poor fuel economy

Fix: The computer-controlled carb uses a mixture control solenoid and early ECM that both fail frequently. Parts are scarce; most shops rebuild the carb and clean all passages, replace the solenoid, and check ECM grounds. 3-5 hours typical.

Estimated cost: $450-900

Typical onset: 80,000+ mi

Symptoms: HVAC stuck on defrost or floor mode, Cruise control inoperative or surging, Transmission delayed or harsh shifts from modulator leak, Rough idle improving when brake booster line is pinched

Fix: The '79 Riviera uses vacuum for HVAC, cruise, and transmission modulator. Aged rubber lines crack and the central reservoir tank develops leaks. Requires systematic line replacement and smoke testing. 2-4 hours to trace and replace problem areas.

Estimated cost: $250-600