180° Thermostat
• Robert Shaw 457-180 $4-6
• Stant ??? $4-6
• NAPA p/n 70 (made by Stant) $2.50

160° Thermostat

• Robert Shaw p/n 457-160 $4-6
• Stant p/n ??? $4-6
• Hypertech p/n 1003 (This is the Robert Shaw part) $9-12

Housing Gasket

(see instructions below if you need this or not) GM p/n 25535214 List=$1.35 Discounted=$.95

Tools:

• You need a deepwell 10mm socket
• Standard Screwdriver
• Gasket Scraper or Pen knife
• Ziploc sandwich bag
• Rubberband

Comments: Do this only on a COLD car. ***DO NOT DRIVE TO THE PARTS STORE, DEALER OR PAST GO BEFORE DOING THIS. IT NEEDS TO BE DONE ON A COLD ENGINE.***

I would suggest removing about 1/2qt of DexCool from the cooling system. It would stop from making the mess I had.

1997-1998 need a gasket available from the dealer.

Tell them to look up the part from the exploded view, not from listings, as listing does not show it. Or use part number above.

I got mine at a Chevy dealer, so they are available widely at dealerships, but not at Autozone, etc. yet.

1999 uses a different O-ring that supplants the need for a paper gasket.

Instructions:

1. Drain 1/2-qt (1-litre) of cooling fluid from system using radiator petcock and a clean and dry catch bottle (you will add this back when done)
2. Remove Supercharge Cover or Intake cover if applicable
3. Locate thermostat housing
4. With a screwdriver, carefully ply wire loom holder off of front thermostat bolt.
5. Unbolt thermostat housing (two 10mm) bolts
6. Place a plastic bag over housing and secure with rubberband to minimize dripping of DexCool.
7. Move hose out of way with housing still attached and bag over it.
8. Scrape the old gasket material off the housing mating surface on the block.

   A gasket scraper works great, I used also a pen-knife to get it off even better. I left the thermostat in place to keep gasket material from getting into the cooling fluid. Be careful not to knick up the O-ring. Clean the gasket material fully off of the mating surface.

9. Carefully remove bag from hosend with the housing and add the fluid to your catch bottle from earlier.
10. Clean up the housing and any fluid that got on the outside of your hose
11. Scrape the old gasket material off the housing mating surface.
12. Remove Thermostat
13. Carefully remove black o-ring from thermostat
14. Reuse the O-ring on the new thermostat.
15. Install new thermostat with reused o-ring
16. Place paper gasket in place

    Paper gasket goes with gasket surfactant (reddish) up, and the tab toward the drivers side (if you have a 1997-1998).

17. Place housing back over gasket
18. Insert bolts (longer one toward front of car for wire loom to clip onto)
19. Tighten it up.
20. Start car and check for leaks.
21. Run car about 15 minutes to get fluids moving through the hose again.
22. Turn Car off.
23. Relieve pressure using bleeder valve on top of t-stat housing by turning slowly open with screwdriver. If car is running it will spew forth, so turn car off. This removes air.
24. Be sure that if you replace any coolant, ONLY USE DexCool, and DO NOT ADD WATER TO TOP IT OFF. Place coolant to proper level in coolant tank.
25. Clean car of any drippings.

Whole process from getting tools to cleaning hands took me 20 minutes in the morning before going to work. Your results may vary.

Enjoy a cooler running car. My Regal picked up two less ticks on the gauge.

BTW: The hypertech part is a Robert Shaw t-stat, so save the bucks and get one at AutoZone or PepBoys.

--Rick Tolan

thanks to Terry Reals for the highlights of the process