1980 BUICK RIVIERA

Typical onset: 80,000-130,000 mi

Symptoms: Delayed engagement when shifting from Park to Drive, Slipping between 2nd and 3rd gear under load, Brownish or burnt-smelling transmission fluid, Loss of overdrive function (THM200-4R), Complete failure to move after highway driving

Fix: Factory oil cooler is undersized and prone to clogging. Transmission rebuild with upgraded cooler installation required. 12-16 hours labor for transmission R&R plus rebuild. Add auxiliary cooler and flush lines during rebuild to prevent repeat failure.

Estimated cost: $2,200-3,800

Typical onset: 40,000-80,000 mi

Symptoms: White or blue smoke from exhaust on cold starts, Persistent coolant loss with no visible leaks, Hard starting especially when warm, Rough idle with excessive vibration, Sudden loss of power followed by engine seizure, Metallic knocking from lower engine

Fix: The 350 diesel uses gasoline engine block with inadequate head bolts and weak head gaskets. Head bolts pull threads from block under compression loads. Complete engine replacement is typical solution—rebuilds often fail again. 18-24 hours for engine R&R. Many owners swap to gasoline 350 or 307 Olds V8.

Estimated cost: $4,500-7,500

Typical onset: 60,000-100,000 mi

Symptoms: Heavy clunk when shifting from Reverse to Drive, Vibration through floor at idle in gear, Visible sag of transmission tailshaft, Rubbing noise from driveshaft tunnel under acceleration

Fix: Factory rubber mount deteriorates and transmission drops, stressing linkage and potentially damaging driveshaft. Replace mount and inspect crossmember for cracks. 2-3 hours labor. Often discovered during transmission service.

Estimated cost: $250-450

Typical onset: 70,000-120,000 mi

Symptoms: High idle speed (1,200+ RPM) that won't adjust down, Stalling when coming to a stop, Poor fuel economy (below 12 MPG city), Hesitation on acceleration from stop, Check Engine light on with mixture codes

Fix: E2SE and E4ME throttle body carburetors develop vacuum leaks at base gasket and internal diaphragms fail. Mixture control solenoid fails frequently. Carburetor rebuild with new gaskets and solenoid replacement. 3-4 hours labor. Consider replacing with remanufactured unit.

Estimated cost: $400-750

Typical onset: 100,000-160,000 mi

Symptoms: Metallic grinding when engaging clutch on manual (rare), Excessive crankshaft end play—felt as engine knock, Oil pressure drops at idle after warm-up, Vibration increases when engaging torque converter, Eventually leads to complete bearing seizure

Fix: Thrust bearing wears from age and sustained high-load operation. Requires complete engine teardown to crankshaft R&R. Machine shop work to resurface crank journals if scored. 16-22 hours total labor for removal, machine work, and reassembly.

Estimated cost: $3,200-5,500

Symptoms: Stalling in hot weather after shutting off for 10-15 minutes, Difficulty restarting when engine is hot, Sputtering and loss of power at highway speed, Engine dies and won't restart until fully cooled

Fix: Fuel lines run too close to exhaust manifolds causing vapor lock. In-tank fuel filters on high-mileage cars clog with rust and varnish. Replace fuel filter (inline and in-tank sock), reroute fuel lines away from heat sources, consider adding heat shielding. 2-4 hours labor depending on line routing work.

Estimated cost: $200-500