How to Replace Intake Manifold 99 Pontiac Grand Am
Difficulty: Intermediate · About 90 min · Pontiac Grand Am
Replace the upper intake plenum on a 1999 Pontiac Grand Am, preserving ignition-wire order and sensor connections, renewing disturbed seals, and refilling coolant before checking for vacuum or coolant leaks.
Tools you will need
- Funnel
- 13mm Socket
- Socket Extensions
- Flat Blade Screwdriver
- Torque Wrench
- Phillips Head Screwdriver
- Drain Pan
- 10mm Socket
- Ratchet
- Needle nose pliers
Parts and supplies
- Upper intake plenum
- Plenum gasket
- Coolant
Steps
Label ignition wires and hoses
With the engine cool, mark each spark plug wire by cylinder position before removing it. Photograph the vacuum hose and connector routing so every connection can be restored correctly.
Remove the air intake duct
Loosen the intake clamps, disconnect the vacuum hose and EGR wiring, and lift the duct away. Keep dirt out of the throttle body and cover the opening if needed.
Disconnect plenum components
Remove the throttle body bracket fasteners and disconnect the coil pack support, MAP sensor, EGR valve, and rear vacuum connections as required. Avoid pulling on wires or brittle hoses.
Drain coolant and free the plenum
Place a pan under the radiator and drain enough coolant to safely disconnect the hoses at the plenum. Remove the remaining plenum fasteners and lift the upper section away without damaging the lower intake surface.
Install the replacement plenum
Clean the mating surfaces without letting debris enter the engine. Fit the new gasket, position the replacement plenum, and tighten its fasteners evenly in the specified sequence and to the vehicle torque specification.
Reconnect sensors, hoses, and EGR
Reinstall the MAP sensor, throttle body, coil support, vacuum hoses, coolant lines, and EGR valve with its gasket. Confirm every clamp and electrical connector is fully seated.
Refit the intake and ignition wires
Reconnect the air intake duct and its sensor wiring, then route each spark plug wire back to its labeled cylinder and retaining clip. Check that no wire or hose contacts a hot or moving part.
Refill coolant and inspect
Close the radiator drain and refill with the specified coolant using the proper bleeding procedure. Start the engine, monitor temperature, and inspect for coolant, vacuum, or intake leaks; recheck the level after the engine cools.
Check your vehicle’s repair manual for exact specifications and fit.