Upper Intake Manifold with Gasket for Pontiac Bonneville (1995-2005) 3.8L

Reinforced Upper Intake Manifold Plenum Kit for 1995-2005 Pontiac Bonneville (H-Body / G-Body)

What it Does: The upper intake manifold kit replaces the failure-prone factory plenum on the 1995-2005 Pontiac Bonneville to restore airtight manifold absolute pressure (MAP) seals and prevent catastrophic engine coolant ingestion.

The Stock Pontiac Bonneville Intake Plenum Weakness

The factory nylon composite upper plenum on the GM 3800 Series II engine features a critical design flaw adjacent to the Exhaust Gas Recirculation (EGR) passage. Over repeated thermal cycles, extreme exhaust gas temperatures degrade the unshielded composite plastic directly surrounding the internal EGR chimney. As the material weakens and decomposes, engine coolant running through adjacent bypass ports leaks directly into the intake tract and cylinder runners. Left unaddressed, this progressive erosion causes severe vacuum loss, unmetered air intrusion, rough idling, coolant consumption, and fatal hydraulic lock in the combustion chambers of H-Body and G-Body sedans.

The Engineering Solution

This replacement upper plenum is engineered with premium heat-stabilized polyamide composite capable of resisting thermal degradation and cyclic fatigue. The mating face features reinforced sealing lands that accommodate the included heavy-duty carrier gasket with molded fluoroelastomer port seals. Designed to exact OEM geometry, it bolts directly to the lower aluminum runner housing while maintaining structural rigidity under high engine bay heat soak, guaranteeing consistent airflow distribution and vacuum integrity under wide-open throttle.

What's Included

• 1 Upper Intake Manifold (Reinforced Composite)
• 1 Upper Intake Manifold Gasket with Molded Port Seals
• Fuel Pressure Regulator Spring
• Throttle Body Studs
• O-Rings and Port Fittings

Technical Specifications

Compatibility

• 1995-2005 Pontiac Bonneville 3.8L V6 Gas Naturally Aspirated (L36)
• 1995-1999 Pontiac Bonneville 3.8L V6 Gas Supercharged (L67)

Frequently Asked Questions & Fitment Warnings

Does this fit the H-Body / G-Body Bonneville?

Yes, this is a direct fit for the 1995-2005 Pontiac Bonneville equipped with the 3800 Series II engine. Note: Does not fit 2000-2005 supercharged models or 2004-2005 Bonneville GXP 4.6L Northstar V8 applications.

What is the correct installation torque sequence?

Torque the plenum bolts in a crisscross sequence starting from the center working outward to factory specifications of 89 in-lbs (10 Nm) on a fully cold engine.

The Pontiac Reliability Standard

Built to withstand years of heavy throttle cycles and daily highway abuse, this manifold assembly preserves the bulletproof durability that GM performance full-size platforms are legendary for.