How to Repair the Water Pump on a 3800 Engine

by Dustin Thornton

The 3800 3.8-liter V6 engine is a popular engine used by GM in several vehicle lines, including Pontiac, Chevrolet, Oldsmobile and Buick. You can replace a damaged water pump in this engine if the vehicle begins displaying signs of water pump failure. Common water pump failure signs include leaking coolant, engine rattling (from the water pump) and loss of the serpentine drive belt while driving. You can perform this repair yourself, saving time and money.

Step 1

Park the vehicle, and open the hood. Shut off the engine, and allow the engine bay to cool for about an hour before removing the water pump.

Step 2

Locate the water pump along the serpentine drive belt, directly above the harmonic balancer on the crank. The water belt is a metal device with a pulley on the front with two metal arms that extend out a few inches on each side. Note that some vehicles might require you to remove the coolant overflow tank to gain access to the water pump. Simply pull the coolant overflow tank directly up along the metal guide track to remove it.

Step 3

Loosen the four bolts securing the water pump pulley to the face of the water pump using a ratchet. Do not remove the bolts; simply break them free.

Step 4

Place a wrench around the idler pulley bolt, and turn counterclockwise to reduce tension on the serpentine drive belt. Remove the belt from around alternator, then release the pulley slowly.

Step 5

Remove the serpentine drive belt, and place it aside.

Step 6

Remove the water pump pulley bolts, and pull the water pump pulley directly off the unit.

Step 7

Remove the water pump mounting bolts around the unit using a ratchet. Remove the water pump itself from the engine. Some coolant might drain out when you remove the unit; this is normal.

Step 8

Clean the water pump mounting surface with a rag. Scrape away any remnants of the old water pump gasket using a putty knife. Make sure the surface is smooth and free of the old gasket before installing a new water pump.

Step 9

Apply a thin strip of high-temperature gasket maker compound around the inner edge of the new water pump.

Step 10

Apply the new gasket to the inner lip of the water pump, being sure to line up the bolt holes in the gasket with the bolt holes on the water pump. The gasket should adhere to the pump because of the gasket maker compound you applied in the previous step.

Step 11

Line up the new water pump with the mounting surface on the engine, and install the bolts you removed earlier.

Step 12

Install the water pump pulley on the new water pump, lining up the four holes on the pulley with the four holes on the face of the water pump. Insert the bolts, and tighten them.

Step 13

Re-route the serpentine drive belt along the accessories (except for the alternator) in the engine using the belt-routing diagram stamped above the radiator.

Step 14

Place a wrench around the idler pulley bolt and turn counterclockwise. Hold it in that position.

Step 15

Lift the belt up, and place it around the alternator pulley. Slowly release the idler pulley, pulling the belt taut.

Step 16

Open the radiator cap, and check the coolant levels. Add coolant, if necessary.

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