You may need to replace a freeze plug. I haven't had to change one on my 2000 Catera yet but I have changed them on my last car (Camry). The freeze plugs are cheap and can be found at many auto parts stores but I found a good selection at Kragen.
Dex-Cool
Where is the engin temperature gauge sensor located on the 1999 cadillac catera?
under the dash on the drivers side
To repair the 1998 Cadillac Catera coolant system, the steps will vary depending on the actual problem. You might need to replace hoses or connections or you might need a new radiator or thermostat.?æ
behind the drivers side head
If there is coolant in your oil on the dip stick, it's a blown head gasket. It will look like chocolate milk.
On the Catera you do not add coolant through the radiator. If you need to add coolant to the cooling system, you should do that through the expansin tank. This located on the passinger side inner fender wall. It looks like a see-thru plasic tank with a yellow cap. Do not open when coolant is hot!
It is located under the coolant reservoir. You can't just replace the sensor. The whole coolant reservoir must be replace. It's a simply 10 minute job.
The coolant temp sensor is located under the plenum, in the back of the motor. Please view my BIO to gain access to my website where i have included a detailed instructions on your catera.
Disc. Remove the wheel. Look on the backside of the caliper and you will see the bolts that hold it. Pretty much the same as any other.
Coolant temp is about 196F. Mine runs cool on a highway, 2 notches below the red line on hot days in traffic.
My 1997 Cadillac Catera does the samething! Normally can be done by the Coolant leaking ,Coolant needing to be flushed, a PCV Valve, Coolant Temperature Sensor, Themostat Sticking, oil cooler, and the list goes on. . You should most likely have a "Experienced" Mechanic look at the vehicle to do a pressure test to make sure you dont have any leaks and to see what is actually wrong.