Upper Intake Manifold with Gasket for Oldsmobile Eighty-Eight (1995-1999) 3.8L

Direct-Replacement Upper Intake Manifold with Gasket for 1995-1999 Oldsmobile Eighty-Eight (H-Body)

What it Does: The Upper Intake Manifold with Gasket replaces the failure-prone factory composite plenum on the 1995-1999 Eighty-Eight to eliminate unmetered vacuum leaks and stop internal coolant migration into the cylinders.

The Stock Oldsmobile Eighty-Eight EGR Thermal Degradation

Factory GM 3800 Series II composite upper plenums on the H-Body platform suffer a notorious engineering vulnerability directly adjacent to the exhaust gas recirculation (EGR) passage. The unshielded factory composite plastic cannot tolerate repetitive high-temperature thermal cycling from exhaust gas flow through the internal stovepipe. Over time, heat soak degrades and thins the nylon manifold wall bordering the coolant crossover passage, ultimately cracking the plenum chamber. This failure introduces engine coolant directly into the intake tract, resulting in severe misfires, vacuum loss, catalytic converter damage, or catastrophic hydrostatic lock.

The Engineering Solution

This replacement upper intake manifold is molded from high-grade, heat-stabilized reinforced nylon polymer engineered to resist prolonged thermal fatigue and EGR port degradation. The intake runner geometry is precision-molded to match factory airflow profiles, ensuring balanced volumetric efficiency across all intake ports without causing diagnostic trouble codes. Supplied with an integrated port seal gasket kit, upgraded throttle body studs, O-rings, and a fuel pressure regulator spring, this direct-fit solution replaces OEM reference 89017274 and restores manifold vacuum integrity, intake pressure retention, and structural resistance against coolant intrusion.

What's Included

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

Technical Specifications

Compatibility

• 1995-1999 Oldsmobile Eighty-Eight 3.8L Gas Naturally Aspirated
• 1995 Oldsmobile Eighty-Eight 3.8L Gas Supercharged
• 1996-1999 Oldsmobile Eighty-Eight LSS 3.8L Gas Naturally Aspirated
• 1996-1999 Oldsmobile Eighty-Eight LSS 3.8L Gas Supercharged

Frequently Asked Questions & Fitment Warnings

Does this fit the H-Body Eighty-Eight?

Yes, this is a direct fit for the 1995-1999 Oldsmobile Eighty-Eight equipped with the 3800 Series II engine. Only the 3.8L V6 applications listed are covered; do not use on non-3800 platforms.

What torque sequence and procedure should be followed during installation?

Torque all intake manifold fasteners strictly to factory GM specifications in the prescribed crisscross sequence on a completely cold engine to prevent warping the composite flange.

The Oldsmobile Reliability Standard

The legendary GM 3800 Series II V6 delivers proven long-term highway reliability when its critical composite intake components are maintained. Installing this reinforced upper manifold assembly preserves factory intake plenum pressure, protects internal engine components from coolant ingestion, and guarantees lasting operational stability for your classic cruiser.