The 1982 Buick LeSabre is a full-size GM B-body with notorious weak points in its THM200-4R overdrive transmission and catastrophic diesel engine failures. The gasoline V6 and V8s are far more reliable, but carburetor issues and intake manifold gasket leaks plague higher-mileage examples.
THM200-4R Transmission Failure
Common · high severityTypical onset: 80,000-130,000 mi
Symptoms: Slipping between 3rd and 4th (overdrive) gear, No movement in any gear after warm-up, Burnt transmission fluid smell, dark or metallic fluid, Shuddering or hard shifts under light throttle
Fix: GM's THM200-4R was undersized for these cars and the overdrive clutches burn out. Full rebuild or replacement required, 8-12 hours labor. Torque converter almost always needs replacement too.
Estimated cost: $1,800-3,200
350ci Diesel Engine Catastrophic Failure
Common · high severityTypical onset: 60,000-100,000 mi
Symptoms: White smoke on startup (head gasket failure into cylinders), Coolant loss with no external leaks, Cracked block or blown head gaskets, Sudden loss of compression, won't start
Fix: The Olds 350 diesel used weak head bolts and gasoline-engine block castings. Head gasket failure leads to cracked blocks. Most owners swap to a gasoline 307 or 350—diesel rebuild is 25+ hours and not economical.
Estimated cost: $3,500-6,000
Intake Manifold Gasket Leak (V6 and V8)
Common · medium severityTypical onset: 70,000-120,000 mi
Symptoms: Coolant seeping from intake valley, visible at front or rear of manifold, Overheating or erratic temperature gauge, Rough idle or misfires from coolant in cylinders, Oil contamination with coolant (milky dipstick)
Fix: GM's composite intake gaskets deteriorate. Requires manifold removal, new gaskets, and thermostat while you're in there. 4-6 hours labor on V6, 5-7 on V8.
Estimated cost: $600-1,100
Rochester Quadrajet Carburetor Issues
Common · low severitySymptoms: Hard starting when cold or hot, Flooding, fuel smell, black smoke, Hesitation or stumble on acceleration, Poor fuel economy (under 12 mpg city)
Fix: The Q-jet is rebuildable but needs proper experience—accelerator pump, power piston, and choke adjustments are common. DIY rebuild kits are $60-100, but most shops charge 2-3 hours to do it right.
Estimated cost: $250-500
Oil Pump Failure Leading to Engine Bearing Damage
Occasional · high severityTypical onset: 100,000-150,000 mi
Symptoms: Low or zero oil pressure at idle, Knocking or ticking from bottom end, Oil light flickering or staying on, Metal shavings in oil filter or pan
Fix: Weak oil pump gears or worn passages kill oil pressure, wiping out rod and main bearings. Requires engine teardown—main and rod bearing replacement minimum, sometimes crank polish or replacement. 16-24 hours labor.
Estimated cost: $2,200-4,500
Front Engine Mount and Transmission Mount Collapse
Common · medium severityTypical onset: 80,000-140,000 mi
Symptoms: Clunk when shifting into Drive or Reverse, Excessive vibration at idle in gear, Engine rocking visible under throttle, Transmission shifter feels loose or sloppy
Fix: Rubber mounts rot out and cause driveline slop and harsh engagement. Replace both engine mounts and the rear transmission mount as a set. 2-3 hours labor total.
Estimated cost: $300-550
Fuel System Rust and Sending Unit Failure
Occasional · medium severitySymptoms: Fuel gauge reads empty, full, or erratic regardless of fuel level, Fuel pump quits after sitting (varnish buildup), Rust flakes in fuel filter, Hard starting after sitting overnight
Fix: Steel tanks rust from inside, contaminating fuel system and killing pumps. Sending unit float arms corrode. Tank drop, clean or replace, new sending unit, new fuel filter and pump. 4-6 hours.
Estimated cost: $500-1,000
Buy the 231 V6 or 305/350 gas V8 versions only, budget $2k for transmission work, and you've got a comfy cruiser—skip any diesel model entirely.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.