Saab V4 Engine Theromostat Replacement

This is simply a guide (not 100% perfect) to show you how to replace your engine thermostat, or try to fix your current one.

Tools:
Screw Driver, 13mm socket wrench (a 13mm open ended wrench is helpful too), new thermostat housing gaskets, new thermostat (if desired)

1)Remove air filter housing
Attachment 125

2)Drain coolant from radiator.

3)Disconnect the three coolant hoses connected to the thermostat housing. It's easiest if the hoses are completely removed from the car so they are out of the way.
Attachment 126

4)Unscrew the three bolts (13mm) that hold the thermostat housing on. The one closest to the carburetor is a tight fit, so an open ended wrench works best there. Even better is doing this job with the carburetor off if you can.
Attachment 127

5)Lift the thermostat housing off and set aside. This is what you should see. Hopefully it's less corroded than this.
Attachment 128
There is the thermostat sitting in the lower half of the housing. Below is the upper half... look at all the corrosion.
Attachment 129

6)Lift the thermostat straight up and out. DO NOT PRY THE THERMOSTAT UP. THE BOTTOM HALF OF THE HOUSING CAN EASILY BE DAMAGED. If you are not planning on using this thermostat again, don't be afraid to use pliers on the top of the thermostat to get it out. Be sure to get the rubber gasket out too.
Attachment 130

7)This is a perfect time to clean the housing (Mine was caked with corrosion). Make sure to get the two sealing surfaces clean, and remove all remnants of the old gasket.

8)If checking the to see the old thermostat is working correctly, hang it from a string, and let it soak in a pot of water on the stove. Use the string so it is suspended in the water, along with a thermometer. If it is an old style thermostat (on older V4 engines) it should open at 181 degrees F, if it is a newer style, it should open at 189 degrees F. I'm not positive on the year they switched.

9)I chose to replace the thermostat. I got a new one from Skandix, and it came with new gaskets. So put the rubber gasket it and thermostat. The lip of the thermostat should sit flush, or just below, the bottom half of the thermostat housing. (Mine sat above with the new gasket, and I cracked the top half of the housing when tightening. This caused some problems, and forced me to get a new top half of the housing... putting me back a couple days while I looked for one. In the end, I used the old rubber gasket, it was still good and not cracked).
Attachment 131

10)Put the new housing gasket on, make sure it sits over the thermostat, and not under it.

11)Replace and tighten bolts. Don't over tighten, the housing is pretty soft, and will easily crack.

12)Reconnect coolant hoses, and put the air filter housing back on.

13)Personally, I suggest giving the cooling system a quick flush after this, just in case you got some grime or dirt down there while working on it. I know I got some down there, it isn't hard to do, and you can check for leaks.

14)Fill with coolant, and bleed the coolant system. To bleed, merely open the petcock (located on the passenger side of the heater fan), turn on the car, and leave the petcock open until coolant comes out with no bubbles, gurgles or air. You are all set. Take it around the block, and check to make sure everything is working properly, and check for leaks.