The 1999 Park Avenue on GM's C-body is a comfortable highway cruiser with the 3800 Series II V6 (or supercharged Ultra). Main issues revolve around intake manifold gaskets, transmission cooler lines, brake booster corrosion, and supercharger coupler wear on Ultra models.
Upper & Lower Intake Manifold Gasket Failure
Common · high severity
Typical onset: 80,000-120,000 mi
Symptoms: Coolant loss with no visible external leak, White smoke from exhaust on cold start, Rough idle or misfire codes (coolant entering cylinders), Oil looks milky brown (coolant mixing with oil)
Fix: Replace upper and lower intake gaskets, EGR valve gasket, and coolant thermostat while apart. Requires removing supercharger on Ultra models. 6-8 labor hours for naturally aspirated, 8-10 for Ultra.
Estimated cost: $800-1,400
Transmission Oil Cooler Line Corrosion & Leaks
Common · high severity
Typical onset: 100,000-150,000 mi
Symptoms: Red ATF puddle under front of vehicle, Transmission slipping or delayed engagement when fluid is low, Burnt transmission smell if leak goes unnoticed
Fix: Steel cooler lines rust through at fittings or bends, especially in salt states. Replace both lines from radiator to transmission. 2-3 labor hours. Ignoring this kills the 4T65E transmission quickly.
Symptoms: Hard brake pedal requiring excessive force, Hissing sound near brake pedal when pressed, Engine idle roughness or stalling when braking, Check engine light with lean codes (P0171/P0174)
Fix: Check valve fails or booster diaphragm tears, creating vacuum leak. Replace booster assembly or rebuild if available. Was subject to GM recall 00V202000 but many cars fell through cracks. 3-4 labor hours.
Estimated cost: $400-700
Supercharger Coupler Wear (Ultra Models Only)
Occasional · medium severity
Typical onset: 100,000-150,000 mi
Symptoms: Whining or squealing from supercharger that changes with RPM, Loss of boost pressure and performance, Visible rubber dust around supercharger snout
Fix: Rubber coupler between supercharger and snout wears out. Aftermarket upgraded couplers available. Requires removing supercharger, replacing coupler and snout bearings if worn. 4-5 labor hours.
Estimated cost: $500-900
Front Engine Mount (Torque Strut) Failure
Occasional · low severity
Typical onset: 80,000-130,000 mi
Symptoms: Clunk or thud when accelerating or shifting into gear, Excessive engine rocking visible under hood, Vibration felt through steering wheel at idle
Fix: Hydraulic torque strut mount fails, letting engine move excessively. Replace strut mount assembly. 1.5-2 labor hours.
Estimated cost: $250-400
ABS Pressure Modulator Valve (EBCM) Failure
Occasional · medium severity
Typical onset: 120,000-180,000 mi
Symptoms: ABS and traction control warning lights illuminated, Reduced brake pedal feel or soft pedal, Brake pedal pulses even during normal stops
Fix: Electronic brake control module solenoids stick or fail internally. Requires used or remanufactured unit, must be bled with Tech 2 scan tool for proper function. 2-3 labor hours plus bleeding procedure.
Estimated cost: $600-1,200
Power Window Regulator Failure
Common · low severity
Typical onset: 90,000-150,000 mi
Symptoms: Window drops into door or falls slowly, Grinding or clicking noise when operating window, Window operates in one direction only or not at all
Fix: Plastic regulator components break, especially front windows. Replace regulator assembly and motor if binding damaged it. 2-2.5 labor hours per door.
Estimated cost: $300-500
Owner tips
Flush coolant every 3 years and inspect carefully for intake gasket weeping before it becomes catastrophic
Check transmission cooler lines annually in rust-belt states; catch corrosion early
Use AC Delco or Dexcool-compatible coolant only; other types accelerate gasket deterioration
Replace supercharger oil every 30,000 mi on Ultra models; uses special synthetic
Budget for brake booster replacement as preventive maintenance above 100k miles
Solid highway cruiser if intake gaskets and cooler lines have been done; budget $1,500-2,000 for deferred maintenance on any sub-$3,000 example and you'll have a comfortable 200k-mile car.
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.
Fitment notes: Side post terminals standard on GM vehicles; supercharged engine requires higher CCA rating
As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Every control module on the 1997-2005 Buick Park Avenue — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
⚠️ Optional; stores two driver positions; mirror memory integrated
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
ON CERTAIN PASSENGER VEHICLES EQUIPPED WITH 3800 V6 (L36) ENGINES AND CERTAIN DELPHI FUEL PRESSURE REGULATORS, THE REGULATORS HAVE A MUCH HIGHER THAN USUAL RATE OF FUEL LEAKS. A LEAK CAN ALLOW FUEL TO ENTER THE INTAKE MANIFOLD THROUGH A VACUUM LINE. IF THE ENGINE DOES NOT START WHEN CRANKED, THE FUEL FROM THE LEAKING REGULATOR AND A MISTIMED SPARK CAN CAUSE A BACKFIRE.
Consequence: THE BACKFIRE CAN RUPTURE THE INTAKE MANIFOLD. THE RUPTURE OF THE INTAKE MANIFOLD CAN DISPLACE A FUEL LINE, PULLING AN INJECTOR OUT OF PLACE, AND CAUSING A FUEL LEAK AND POSSIBLE FIRE.
Remedy: DEALERS WILL INSTALL NEW FUEL PRESSURE REGULATORS WITH IMPROVED DIAPHRAGMS. THE RECALL WILL BE CONDUCTED IN PHASED MAILINGS. PHASE 1 BEGAN ON JUNE 30, 2004, AND PHASE 2 BEGAN ON SEPTEMBER 30, 2004. OWNERS SHOULD CONTACT BUICK AT 1-866-608-8080, OLDSMOBILE AT 1-800-630-6537, OR PONTIAC AT 1-800-620-7668.
SERVICE BRAKES, HYDRAULIC:POWER ASSIST:VACUUM · 99V238000
1999-08-27
VEHICLE DESCRIPTION: PASSENGER VEHICLES. THE BRAKE BOOSTER TO PEDAL ASSEMBLY ATTACHMENT NUTS MAY BE LOOSE.
Consequence: IF THESE NUTS ARE LOOSE, THE BRAKE PEDAL MAY BE LOW, THE ASSEMBLY MAY BE LOOSE, THE BRAKES MAY NOT RELEASE, AND IF THE NUTS BACK COMPLETELY OFF, BRAKING MAY BE LOST. ALSO FUME AND WATER INTRUSION TO THE PASSENGER COMPARTMENT CAN OCCUR.
Remedy: DEALERS WILL REPLACE ANY MISSING BRAKE BOOSTER TO BRAKE PEDAL ASSEMBLY NUTS AND TIGHTEN ALL FOUR (4) NUTS TO SPECIFIED TORQUE.
SERVICE BRAKES, HYDRAULIC:FOUNDATION COMPONENTS:DISC · 99V081000
1999-04-14
VEHICLE DESCRIPTION: PASSENGER VEHICLES. THESE VEHICLES MAY HAVE BEEN BUILT WITH INCORRECT FRONT BRAKE ROTOR, BRAKE CALIPER ASSEMBLY, BRAKE PADS, AND CALIPER MOUNTING BRACKET ON EITHER THE LEFT OR RIGHT SIDE OF THE VEHICLE.
Consequence: A VEHICLE WITH THIS CONDITION CAN PULL TO ONE SIDE DURING A BRAKING MANEUVER. IN ADDITION, VEHICLE STOPPING DISTANCE COULD BE INCREASED.
Remedy: DEALERS WILL INSPECT FOR CORRECT BRAKE PARTS AND REPLACE ANY INCORRECT ROTORS, CALIPER ASSEMBLIES, BRAKE PADS, AND CALIPER MOUNTING BRACKETS.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 1999 Buick Park Avenue 3.8L Supercharged V6 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Mechanic · 20+ years.