1999 Chevrolet Venture Change the Thermostat

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Chevrolet discontinued production of its Lumina APV minivan in 1997, replacing it with the Venture model. The Venture lasted through the 2005 model year; it was replaced the following year by the Uplander model. The 1999 Chevrolet Venture came fitted with a 3.4-liter V-6 engine that produced 185 horsepower and 210 foot-pounds of torque. A mixture of Dex-Cool coolant and water, cooled by a fan and regulated by a thermostat, cools the Venture's engine. Changing the thermostat in that 1999 Venture is a task that most moderate-level do-it-yourself mechanics can perform.

Tools Used[edit]

Phillips screwdriver
Floor jack
Jack stands
Channel lock pliers
Socket set
Plastic gasket scraper
Torque wrench
Flat-head screwdriver
3 gallons 50/50 premixed Dex-Cool coolant

Change the Thermostat[edit]

  • Loosen the four screws that hold the two halves of the air box together, using a Phillips screwdriver. Loosen the clamp that holds the flexible tube from the top half of the air box to the intake tube, at the front of the engine. Pull the top half of the air box out of the Venture, along with the air filter.
  • Raise the front of the Venture with a floor jack and slide jack stands under the sub-frame. Lower the Venture until only the jack stands support its weight.
  • Crawl under the vehicle and locate the petcock -- the plastic thumbscrew at the lower-left of the radiator. Place a drain pan under the petcock and turn the petcock counterclockwise to allow fluid to drain from the radiator and into the drain pan. Tighten the petcock once the coolant stops flowing from the petcock.
  • Pull the drain pan from under the Venture and lower the van to the ground.
  • Trace the upper radiator hose until you locate the metal housing, known as the thermostat housing, at the end of the hose, directly above the transmission. Release the hose clamp on the end of the upper radiator hose, using channel lock pliers, and slide the clamp a few inches down the hose. Pull the hose from the thermostat housing and push it out of the way.
  • Remove the two bolts that secure the thermostat housing to the engine, using a ratchet and socket, then pull the housing away from the engine, exposing the thermostat below it.
  • Grab the thermostat and pull it from the engine.
  • Scrape the mating surfaces on both the engine and the thermostat housing with a plastic gasket-scraper. This cleans off any debris, allowing for a good seal. Don't use a metal scraper, as this may cause damage to the mating surface and create a leak.
  • Install the rubber gasket around the perimeter of the new thermostat, if not already installed. Place the new thermostat into the hole in the engine, with the spring side inserted into the engine.
  • Apply a thin coat of RTV silicone to the threads and head of both thermostat housing bolts and install the thermostat housing. Tighten the thermostat housing bolts to 18 foot-pounds, using a torque wrench and socket.
  • Install the upper radiator hose onto the thermostat housing and slide the hose clamp to the end of the hose, using channel lock pliers, to secure the hose in place.
  • Push the flexible hose that goes to the top half of the air box back onto the intake hose and tighten the hose clamp, using a Phillips screwdriver. Place the air filter in the top half of the air box and connect the top and bottom halves together. Tighten the four screws, using a Phillips head screwdriver.
  • Loosen the bleeder valve -- the small screw on top of the thermostat housing -- with a flat-head screwdriver. Fill the radiator with 50/50 premixed Dex-Cool coolant and start the Venture's engine.
  • Allow the engine to run for approximately two minutes while closely monitoring the coolant temperature and level. Add 50/50 premixed Dex-Cool coolant each time the level drops (as air bleeds from the coolant system).
  • Close the radiator cap and bleeder valve once the coolant level remains steady and no more air bubbles appear in the radiator. Shut down the Venture's engine.
  • Allow the engine to cool for 30 minutes and check the coolant level in the coolant reservoir. Add 50/50 premixed Dex-Cool coolant to the reservoir until the level is between the "Min" and "Max" lines. The entire coolant system takes 2.4 gallons of coolant.
  • Take the old coolant to a local automotive fluid recycling center. Many auto parts stores perform this task free of charge.

Tips & Warnings[edit]

  • Dex-Cool coolant is highly toxic, so keep it away from small children and animals.