1986 BUICK LESABRE

Typical onset: 80,000-140,000 mi

Symptoms: Slipping between 2nd and 3rd gear, especially under load, Delayed engagement when shifting from Park to Drive, Shuddering or harsh shifts, Transmission fluid dark brown or burnt smell

Fix: The 200-4R and THM200 transmissions in these cars have weak intermediate band servos and tend to burn clutches. Rebuild requires 12-16 hours labor including R&R. Many shops recommend upgrading internal components during rebuild. Transmission oil cooler should be replaced simultaneously to prevent contamination.

Estimated cost: $1,800-3,200

Typical onset: 100,000-150,000 mi

Symptoms: Burning through 1+ quart of oil every 500-800 miles, Blue smoke on startup or acceleration, Oil fouling on spark plugs, Poor idle quality when warm

Fix: Worn piston rings and valve seals are the culprits. Ring replacement alone is 18-22 hours (engine stays in car, oil pan and head removal required). Many owners opt for used low-mileage engine swap (10-14 hours) or full rebuild (25-35 hours) if compression is poor across multiple cylinders.

Estimated cost: $2,200-4,800

Typical onset: 15+ years regardless of miles

Symptoms: Transmission fluid puddle under front of vehicle, Sudden loss of all gears while driving, Fluid level drops rapidly, Lines visibly corroded at radiator connection

Fix: Steel cooler lines rust through where they connect to the radiator or at frame mounting points. Requires replacement of both lines (they're cheap, $40-80 in parts). Labor is 2-3 hours due to routing complexity and seized fittings. Critical repair—running low on ATF will destroy the transmission in minutes.

Estimated cost: $250-450

Typical onset: 90,000-130,000 mi

Symptoms: Coolant loss with no visible external leak, White residue around intake manifold edges, Rough idle or misfire when cold, Coolant smell from engine bay

Fix: The composite intake gaskets deteriorate and allow coolant into the crankcase or combustion chambers. Gasket set runs $80-120, labor is 4-6 hours to remove intake, clean surfaces, and reassemble. Check for milky oil—if coolant has mixed with oil for a while, bearings may be compromised.

Estimated cost: $450-750

Symptoms: Hard starting when cold, Stalling at idle or when coming to a stop, Black smoke from exhaust, Poor fuel economy (under 15 mpg)

Fix: The Rochester E2ME/E2SE carburetors get gummed up and the mixture control solenoid fails. Rebuild kits are $60-90, labor is 3-5 hours for a proper rebuild including adjustment. Many techs recommend ultrasonic cleaning. Note: 1986 may have TBI depending on build date—check before ordering parts.

Estimated cost: $300-550

Typical onset: 80,000+ mi or 20+ years

Symptoms: Loud clunk when shifting from Reverse to Drive, Vibration at idle in gear, Excessive driveline movement visible under throttle

Fix: The rubber isolator in the rear trans mount deteriorates and the transmission tail shaft drops. Replacement is straightforward—1.5-2 hours labor including safely supporting the transmission. Parts are $40-70. Ignore it too long and you'll stress the cooler lines.

Estimated cost: $150-280