The 2002 Buick Regal on the W-body platform shares the venerable 3800 V6 (Series II), but transmission cooling system failures and lower-intake manifold gasket leaks are the two dominant gremlins. The supercharged GS variant adds potential supercharger coupler and intercooler issues.
Lower Intake Manifold Gasket Failure (3.8L V6)
Common · medium severityTypical onset: 80,000-140,000 mi
Symptoms: Coolant puddles under the engine, often pink/orange drips between bell-housing and block, White smoke on cold start that clears up, Coolant loss with no external leaks visible from above, Rough idle or misfire if coolant seeps into cylinders
Fix: Remove upper plenum and intake runners to access lower gasket set. Dexcool leaves orange sludge that must be cleaned thoroughly. Job takes 4-5 hours for an experienced tech. Replace upper plenum gaskets while you're in there—they're cheap insurance.
Estimated cost: $650-950
Transmission Oil Cooler Line Corrosion and Failure
Common · high severityTypical onset: 90,000-150,000 mi
Symptoms: Red ATF pooling under the radiator or along frame rails, Transmission slipping or delayed engagement after fluid loss, Coolant in transmission (milky/pink fluid on dipstick) if internal radiator failure, Rust holes visible on steel cooler lines near radiator
Fix: Steel cooler lines rust through where they clip to the frame and radiator. Replace both lines—they're sold as a set. If the radiator's internal trans cooler failed and contaminated ATF with coolant, you need a flush, possibly a trans rebuild. Line replacement alone: 2-3 hours. With radiator: add 1.5 hours. Trans contamination repairs can escalate to full rebuild.
Estimated cost: $400-700 (lines only); $2,500-3,800 (if trans rebuild needed)
4T65E Transmission Torque Converter Shudder and Failure
Occasional · high severityTypical onset: 100,000-180,000 mi
Symptoms: Shudder or vibration at 40-50 mph during light throttle (feels like rumble strips), Delayed 1-2 or 2-3 upshift, Slipping under acceleration, Check engine light with P0741 (torque converter clutch stuck off)
Fix: The 4T65E's torque converter clutch wears or the apply valve sticks. Fluid and filter service sometimes buys time if caught early, but most need converter replacement or full rebuild. Trans R&R is 6-8 hours; if you're doing the converter, budget for a full overhaul with updated clutches and pump.
Estimated cost: $1,800-3,200
Supercharger Coupler Failure (3.8L Supercharged GS only)
Occasional · medium severityTypical onset: 70,000-120,000 mi
Symptoms: Sudden loss of boost and power, Loud rattling or grinding noise from belt area at idle, Visible rubber shreds in supercharger snout area, No check engine light—mechanical failure only
Fix: The rubber isolator coupler between crank pulley and supercharger disintegrates. Remove supercharger (4 bolts), replace coupler and front bearing. ZZP and other aftermarket vendors sell upgraded Teflon couplers. Labor is 3-4 hours if you've done it before; first-timers allow 5-6 hours. Replace the supercharger oil while it's off.
Estimated cost: $450-750
Power Steering Pressure Hose Leak
Common · low severityTypical onset: 100,000-160,000 mi
Symptoms: Power steering fluid dripping from engine bay, often near firewall, Whining or groaning when turning at low speed, Low fluid level despite top-ups, Hose visibly cracked or seeping at crimp fittings
Fix: High-pressure hose from pump to rack cracks at the crimps or along the rubber. It snakes behind the engine—tight access. Budget 2-3 hours. Use OEM or quality aftermarket (avoid cheap eBay specials that burst). Flush and bleed system after replacement.
Estimated cost: $250-450
Front Engine Mount (Torque Strut) Failure
Common · low severityTypical onset: 80,000-130,000 mi
Symptoms: Clunk or thud when shifting from Park to Drive or Reverse, Excessive engine movement visible from under the hood during acceleration, Vibration through steering wheel or floor at idle, Physical inspection shows torn rubber or separated metal bracket
Fix: The upper torque strut mount (dogbone) tears. It's a 1-hour job with basic hand tools—three bolts. The supercharged models eat these faster due to extra torque. Aftermarket polyurethane mounts last longer but transmit more vibration.
Estimated cost: $150-280
Solid daily driver if the lower intake gasket and trans cooler lines have been addressed—budget $1,500-2,000 for deferred maintenance on any high-mileage example, but the 3800 will run to 250k+ if you stay ahead of leaks.
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.