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View Full Version : Changing the Thermostat


eljefino
10-23-2003, 01:09 PM
Is your heat mediocre, and the car never fully warms up? Saturn' S-series (at least my 95 SW1) has a funky thermostat that's somewhat different from others. Note: Be sure to read the ects (http://www.saturnfans.com/forums/showthread.php3?s=&threadid=24003) thread to find out if it's your gauge that's acting up or the off temp is for real. Mine came (used) with a thermostat that failed in the underheating position (stuck open.) They can also get "sticky" where the cold car heats up above normal then falls down to normal for the rest of the drive.

The part is expensive as these go, $14 from NAPA. It might come with a new o-ring; mine did but I left the old one stuck to the block as it looked okay. The O-ring does the job those stupid gaskets and RTV used to do, and, IMHO, better.

Drain the coolant first from the radiator peacock on the passenger side. Open the surge tank cap to make it go faster. The thermostat is behind a "gooseneck" that the bottom curvy big radiator hose goes to. There is also a 3/4" hose that goes up to the surge tank there which can be left alone.

If you have air conditioning you might be tempted to go at it from underneath. Looks like you could if you take the plastic snow guard off. Nope! Frame is in the way. Gotta go at it from above. It'll take a 10mm socket/wrench; I needed my good ones after breaking a 1/4 incher on it. Also needed 18 inches of cheater bar. Be careful using this much muscle.

The "gooseneck" needs to come off the lower radiator hose; undo the clamp. More antifreeze will ooze out here so be ready. The thermostat will come out with it.

The new part should have a cardboard "pipe" a couple inches long. Depress the old thermostat against its spring pressure with this pipe and twist to get it out. Installation is reverse of removal. If yours doesn't include this pipe maybe you could find some 1 inch pvc or big socket to use.

Pry off the old o-ring if you want to use the new one. (probably good mechanical practice). Install the gooseneck, tighten bolts (probably 15-20 ft lbs would be fine), reinstall hose (good time for new one if over 5 yr old), clamp, and antifreeze. After adding your first gallon (which'll go right in) some more will have to be burped out. I used my empty gallon container to mostly empty the drain pan so I could estimate what more I needed to replace. I started the car and it rather quickly burped the rest of the air, then the cap goes on and tightened. Your experience may vary so check the coolant after 1 min, 5 min, 30 min, and 5 days. Check the thermostat area for leaks and you're done!