Upper Intake Manifold with Gasket for Buick Park Avenue (1995-2005) 3.8L

Direct-Fit Upper Intake Manifold with Gasket for 1995-2005 Buick Park Avenue (C/G-Body)

What it Does: The Upper Intake Manifold replaces the failure-prone factory plenum on the 1995-2005 Buick Park Avenue to eliminate unmetered vacuum leaks and prevent catastrophic internal coolant intrusion.

The Stock Buick Park Avenue Thermal Degradation Failure

Factory nylon plenums on the GM 3800 Series II (L36) engine suffer chronic failure adjacent to the hot exhaust gas recirculation (EGR) passage. Continuous heat cycling and hot exhaust gases passing through the internal stovepipe degrade the OEM composite polymer, causing the plastic wall surrounding the coolant jacket ports to thin, warp, and rupture. This structural breakdown allows pressurized engine coolant to seep directly into the intake tract and cylinders, triggering misfires, catalytic converter fouling, or complete engine hydrolock.

The Engineering Solution

This replacement upper intake plenum is molded from reinforced, heat-stabilized composite polymer engineered to resist prolonged thermal cycling and chemical exposure. Featuring optimized internal runner walls and a reinforced EGR passage zone, this assembly restores factory manifold absolute pressure (MAP) integrity and eliminates manifold-related vacuum leaks. The kit includes a precision-molded perimeter port gasket with integrated elastomeric seals, preventing external vacuum loss and internal cross-port leakage without altering factory engine management calibration.

What's Included

• 1 Upper Intake Manifold (plastic composite plenum)
• 1 Upper Intake Manifold Gasket with port seals
• Fuel pressure regulator spring
• Throttle body studs
• O-rings and installation fittings

Technical Specifications

Compatibility

• 1995-2005 Buick Park Avenue 3.8L V6 Gas Naturally Aspirated
• 1999 Buick Park Avenue 3.8L V6 Gas Supercharged

Frequently Asked Questions & Fitment Warnings

Does this fit the G-Body Park Avenue?

Yes, this is a direct fit for the 1995-2005 Buick Park Avenue equipped with the 3800 Series II naturally aspirated V6. Does not fit 1995-1998 or 2000-2005 Supercharged (L67) cast aluminum lower-to-blower configurations.

What is the critical installation procedure for this manifold?

Install on a completely cold engine and torque all manifold fasteners to 89 lb-in (10 Nm) in factory criss-cross sequence to prevent warpage.

The Buick Reliability Standard

The GM 3800 platform is recognized for bottom-end longevity; installing an updated, heat-resistant upper plenum eliminates its primary vulnerability to ensure long-term operating reliability without check engine lights.