Upper Intake Manifold with Gasket for Buick Riviera (1995-1997) 3.8L

Reinforced Upper Intake Manifold Kit for 1995-1997 Buick Riviera (G-Body)

What it Does: The Upper Intake Manifold with Gasket replaces the factory composite plenum on the 1995-1997 Buick Riviera to eliminate vacuum leaks, prevent catastrophic internal coolant loss, and restore factory air distribution.

The Stock Buick Riviera Plenum Vulnerability

The factory upper intake plenum on GM's 3800 Series II V6 is molded from an unreinforced nylon composite that deteriorates under prolonged heat cycling. Specifically, hot exhaust gases flowing through the unshielded Exhaust Gas Recirculation (EGR) passage cook and erode the surrounding plastic wall directly adjacent to the coolant metering passages. Over time, this thermal fatigue causes wall burnout, allowing pressurized engine coolant to seep into the intake runners. Left unaddressed on the G-Body platform, this failure causes misfires, oxygen sensor fouling, and severe internal hydro-locking.

The Engineering Solution

This replacement upper intake plenum is molded from high-grade, heat-stabilized polymer engineered to resist EGR thermal erosion and chemical breakdown from modern coolant formulations. Reinforced structural webbing around critical vacuum bosses and runner ports prevents flange deflection under engine bay heat-soak. Supplied with an engineered upper intake manifold gasket featuring high-recovery elastomer port seals, this kit seals tightly against OEM lower intake manifolds, effectively replacing failure-prone OEM numbers like 12537425 and 89017274 with lasting dimensional stability.

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

Technical Specifications

Compatibility

• Riviera 3.8L Gas Naturally Aspirated — 1995-1997
• Riviera 3.8L Gas Supercharged — 1995-1997

Frequently Asked Questions & Fitment Warnings

Does this fit the G-Body Riviera?

Yes, this is a direct fit for the 1995-1997 Buick Riviera equipped with the 3800 Series II engine; it does not fit models outside the 1995-1997 model range or non-3.8L engine configurations.

Is a specific torque sequence required during installation?

Yes, always install on a cold engine and torque all manifold fasteners to factory inch-pound specifications in the proper cross-pattern sequence to prevent localized stress fractures.

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Engineered to uphold the effortless power delivery and legendary cabin refinement expected of Buick's premier personal luxury coupe, maintaining peak reliability for miles ahead.