How to Replace a PCV Valve on a Buick 3800

by Kyle McBride

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Buick equipped the V-6 3800 (Fireball) engines with a positive crankcase ventilation (PCV) valve to vent crankcase gasses into the intake manifold. The combustion process burns off these gasses. Engines that are old, brand new (not yet broken in) or damaged allow an excessive amount of blow-by gasses past the rings and into the crankcase. Engine vacuum and PCV spring pressure work together to regulate the amount of fresh air from the breather that is allowed to circulate through the crankcase. Dirty or fouled PCV valves cause the blow-by gasses to pressurize the crankcase and lead to oil leaks and an oil-soaked breather filter. Determine whether you have the L36 or L67 engine from your owner's manual or from the decal on the fan shroud under the hood.

L36 Engine

Step 1

Unscrew the oil filler neck from the engine shield by hand. Raise the front edge of the shield by hand and pull it forward and off of the engine.

Step 2

Locate the manifold absolute pressure (MAP) sensor on the front end of the intake manifold. Spread the MAP sensor retainers slightly and pull the sensor from the PCV cap by hand.

Step 3

Push the PCV cap down and rotate it 1/4 turn counterclockwise with a 16-mm socket. Lift the PCV cap off and pull the PCV valve and O-ring out of the manifold by hand.

Step 4

Place the new O-ring on the new PCV valve. Insert the new valve into the intake manifold.

Step 5

Position the PCV cap over the valve. Push it down and rotate 1/4 turn clockwise to engage the cap to the manifold.

Step 6

Push the MAP sensor into the PCV cap until the retainers snap into place.

Step 7

Place the rear of the engine shield in position against the shield bracket. Lay the front of the shield onto the engine.

Step 8

Align the engine oil filler hole. Screw in the oil filler neck by hand.

L67 Engine

Step 1

Remove the engine shield retainer nut from the center of the shield with a ratchet and socket. Unscrew the oil filler neck by hand. Raise the front edge of the shield up and pull it forward and off of the engine.

Step 2

Push down on the PCV cover. Remove the two cover retainer screws with a wrench. Slowly release the spring-loaded cap. Pull the PCV valve, spring and O-ring from the housing.

Step 3

Install the new O-ring onto the new PCV valve. Insert the PCV valve and spring into the housing. Push the cap down over the valve and spring and install the retainer screws. Torque them to 89 inch-pounds with a 1/4-inch torque wrench and socket.

Step 4

Position the rear of the engine shield against the shield bracket. Lay the front of the shield down. Align the oil filler holes and install the filler neck by hand.