• Tiny
  • chrishenry
  • 1999 Chevrolet Astro

Engine Cooling problem
1999 Chevy Astro 6 cyl Two Wheel Drive Automatic 115000 miles

I have no heat in my 1999 Chevy Astro van and it is cold out. The engine light came on a I did a diagnostic at Advance Auto parts. He said the code was for the thermostat.I didn't tell him I had no heat but he asked me after the test. I bought a thermostat and my son will put it on but he doesn't know where the thermostat is located. Could someone tell me how to replace the thermostat?

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have the same problem?
Friday, January 9th, 2009 AT 7:46 PM

1 Reply

  • Tiny
  • bluelightnin6
  • Expert
  • 17,061 posts

The thermostat is located at the front of the intake manifold.

Disconnect the negative battery cable for safety.
Place a catch pan under the radiator, open the drain cock and drain the cooling system to a level below the thermostat housing.

When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.


Remove the thermostat housing-to-engine bolts or bolt and stud, as applicable.
Separate the housing from the manifold and carefully remove the thermostat.
Using a plastic scraper, clean the gasket mounting surfaces.

Sometimes, the thermostat will lift from the engine with the housing, but if not, note the direction it is installed, then lift if from the engine for replacement (See figure below)


Tighten the thermostat housing-to-engine bolts or bolt and nut to 18 ft. lbs. (25 Nm).
Connect the battery cable, then properly refill and bleed the cooling system.
Run the engine and check for leaks.

Hope this helps..
Thanks for using 2carpros.com!

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Friday, January 9th, 2009 AT 8:15 PM

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