Upper Intake Manifold with Gasket for Oldsmobile Ninety-Eight (1995-1998) 3.8L

Direct-Fit Upper Intake Manifold with Gasket Kit for 1995-1998 Oldsmobile Ninety-Eight (C-Body)

What it Does: The Upper Intake Manifold with Gasket kit replaces the deteriorated factory nylon plenum on the 1995-1998 Oldsmobile Ninety-Eight to eliminate vacuum leaks and protect against catastrophic internal coolant ingestion.

The Stock Oldsmobile Ninety-Eight Plenum Thermal Failure

The OEM composite plenum on the 3800 Series II engine suffers from a well-documented failure point near the integrated Exhaust Gas Recirculation (EGR) passage. The unshielded steel EGR stovepipe transfers extreme exhaust gas temperatures directly into the surrounding nylon housing. Over repeated thermal cycles, this localized heat softens and thins the composite material until it ruptures. When the barrier fails, pressurized engine coolant from the adjacent cooling ports enters the intake runners, leading to misfires, fouled O2 sensors, and potential engine hydrolock, while warped sealing flanges create chronic unmetered air leaks.

The Engineering Solution

Engineered as a heavy-duty direct replacement, this upper intake manifold utilizes an updated, heat-stabilized polymer matrix designed to resist thermal degradation around high-temp exhaust passages. The runner geometry maintains balanced plenum volume and factory flow dynamics across all cylinders. Paired with a precision-molded carrier gasket featuring elastomeric port seals, this assembly forms an airtight seal against the lower aluminum manifold, accommodating dynamic thermal expansion without losing clamping torque.

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

• Ninety-Eight 3.8L Gas Naturally Aspirated — 1995-1996
• Ninety-Eight 3.8L Gas Supercharged — 1995
• Ninety-Eight Regency 3.8L Gas Naturally Aspirated — 1997-1998

Frequently Asked Questions & Fitment Warnings

Does this fit the C-Body Ninety-Eight?

Yes, this is a direct fit for the 1995-1998 Oldsmobile Ninety-Eight equipped with the 3800 Series II 3.8L V6 engine. This kit does not fit non-3.8L applications or pre-1995 Series I engines with differing port profiles.

What is the critical installation procedure for this intake?

Fasteners must be torqued on a fully cooled engine to the factory specification of 89 in-lbs in the proper alternating sequence to ensure uniform gasket compression without distorting the composite casing.

The Oldsmobile Durability Standard

Preserve the smooth, long-distance touring reliability of your executive sedan by restoring proper manifold vacuum integrity and isolating vital coolant passages from the induction tract.