I have a 1994 Saturn SL2 DOHC. My problem is when idling the gauge shows the temp slowly climbing to and slightly above half way mark but when I get up on the freeway the gauge will drop all the way to the C-cold mark. Have any ideas?

 

I have had 4 saturns from a 92sl1 to a 99 sl2 and they all have been like yours as far as getting hot while idling for a while. If your fan comes on to keep it from getting hotter then its working ok. You can check your fan by turning on your a/c. The fan should run when the a/c is running. If it does'nt then get a new fan motor. I get mine at autozone for about $30.00. As for your guage going into the cold range when on the highway, I dont know. Maybe your thermostat is bad or maybe someone took it out. Edited by: rick

 

Most cars temp guages drop when they get on the highway or any open area where your moving fast and not stopping. You are pushing more air over the radiator and removing more heat from the coolant at a faster rate of speed. Saturns have small grills which don't allow as much air to move through the radiator. So when your sitting still no air moves to cool the coolant until the fan kicks on.

 

I had that problem really bad with my '94 SC2. It was even climbing going at high speeds. I installed a switch to cut the fan on whenever the gauge starts climbing too high.

 

I know you guys think I am hooked on changing the ECTS but it works I know from experiance.





Also saturns are designed to run fairly hot about the 1/4 mark on the temp gauge is a good temp running cold is not good for your fuel economy because a cold engineis not burning fuel properly.Edited by: 96sl2

 

Change the coolant temperature sensor (CTS) -- older designs (pre -98)
were plastic tipped and are known to be problematic. Replace with
the newer (brass) version.



Also be sure to replace the connector plug at the end of the wiring--
corrosion here often leads to bogus readings from the CTS to the car's
computer.



As for dropping to C on the highway -- if the CTS swap doesn't fix it, it sounds like your thermostat is bad/stuck open.



Derf