I'd go ahead and replace the thermostat if it were mine. Just don't buy a junky one at Autozone or Advance. Get yourself a good one from NAPA or the Saturn friendly dealership in your area if you can find one. I've had several defective t-stats from both the zone and advance over the years. If I absolutely have to get one from either place, I always test it before installation.

 

Just had this problem and with these same symptoms. Turns out the driver-side plastic radiator tank had a small crack where the automatic transmission coolant line connected. No other problems.

As one of the posters said, a whitish "splash" shaped residue on the black parts around the leak was the giveaway.

$68 and a couple of hours and the problem was solved.

 

I don't have a plastic tank on the drivers side that I can see. The only fluids that I can tell aside from some wet around the head is on an opening near the bottom of the radiator. couldn't see to well today.

 

To answer your question as best I can, from the 2000-2002 factory service manual, the fan is supposed to come on at 105.5°C or 222°F, or when the AC is commanded on or a high/low fault exists in the ECT circuit.

The test for the thermostat is to insert a paper clip or similar sized wire between the valve and the body of the thermostat. Hang the thermostat in a pot of water and start heating. when the valve opens enough to drop the thermostat, measure the temp of the water. It should be between 180 and 192°F (83-89°C).

At the bottom of the radiator, there are a couple of places that could leak, besides the core itself. On the passenger side, the lower radiator hose and the drain valve. I have had issues with reusing the drain valve and have had to replace them. They are pretty cheap and you can get them at just about any parts store except AutoZone (go figure). I have not heard of one of these failing during normal use though.

On the drivers side, there is an upper radiator hose near the top and the AT cooling lines. If a leak forms around one of the AT cooling lines, it requires immediate attention because if coolant and ATF mix, it can severely damage your AT, or so I have been told.

Modern radiators are aluminum core with plastic end tanks. By far, the biggest source of leaks with this type of construction is the failure of the rubber seal between the core and the tanks. The plastic tanks are also prone to cracking as they age and that is the second leading cause of failure. Usually a tank will crack around the radiator cap, but the Saturn radiator doesn't have a radiator cap. The surge tank cap serves as the radiator cap.

 

In thinking this is the problem. Drivers side near bottom.

 

If not the bottom one shown above then probably the top one that failed on my son's car.



I could never see the leak when it was sitting, even if idling and there was always a little pressure when I removed the radiator reservoir cap. I suspect when it was cranking 2K rpm or so and the thermostat opened is when it would push the coolant out.

 

Looks like that top one was the problem.

 

You must have a manual transmission unless you disconnected the AT cooler line. That is the bottom port for the cooling line form the AT and it is in a plastic end cap. To the right you see the fingers of the aluminum core that are clamped around the plastic end cap and there is a rubber gasket between the plastic and the aluminum.

Even the manual transmission cars come with the AT cooler, you just don't use it. I guess it is cheaper to use a radiator for AT across the board instead of stopping production to switch over to a manual transmission version of the radiator. All manufacturers seem to do this now.

I can't tell from the picture where the actual leak is.

Are you using Dexcool? Dexcool seems to leave a more visible trail when it finds a leak. I have a 97 Nissan Pick Up that leaked a small amount of coolant, about a cup a month, from the time it was new. when it came due for its first coolant exchange at 3 years, I switched to Dexcool and within a couple weeks, I found the leak. It was an oxide inclusion in the gooseneck casting, under the upper radiator hose.

 

The pic I posted was the only wet spot under my hood around anything to do with the coolant system that I could find. And yes, mine is manual. I keep forgetting to specify that I'm just so used to only driving them sometimes I forget there can be differences.

 

id take both the upper and lower hoses off and inspect them closely to check for damage, if none is fount, pull the radiator, and closely inspect that too