94 olds cutlass s, over heating and temp sensor
 

Hello again , I have a 94 olds cutlass supreme with the 3.1 motor. It has 150,000 miles on the car. My problem is the car overheats when its warm out . the temp is great at highway speeds but any kind of city driving it will start climbing till I have to run the heater at full speed to keep it down. Also I wanted to replace the temp sending unit . How is it removed from the car? Where is it located ? I've looked and am not sure where it is. I thought it may be the ceramic piece on radiator near water intake. Any ideas about what I should look at to get a handle on the overheating problem would be great. Thanks in advance for any help anyone can offer, With this forum I would be dead in the water. gary r

I would see how much heat the radiator is removing. I use an infrared thermometer to read the temp going into the radiator and what it is coming out. I wouldn't worry about your sending unit. It will not cause nor fix overheating problems. I would make sure the thermostat is good and you are full of coolant. Start there.

Here's the component locations for your Old's.

https://cimg2.ibsrv.net/gimg/www.gmf...7053e30195.jpg

Thank you for the quick reply. I have been checking the coolant every time I drive right now. It's been staying good no dip in the level that I notice. Thank's for the diagram of my car. That will a great guide for me. I will let you know how things go. Also is it hard to change the thermostat on this car? thanks again. gary r

Does the radiator fan work?

I'm checking to see what I can find. The fan on driver side seems to come on when air is on high. Haven't had the passenger side fan come on yet that I know of. .Even with air on max cooling .Do you have a test that I can do at home that might give me a idea of the fan is no good or a relay may be the problem.
. Today I removed the relays and cleaned the contacts. I made sure I was very careful and checked the fuses were all good. Thanks for sending me this info. I will check the temp with my laser temp meter. Where is the best place for me to get some temps from. I was thinking of hoses and radiator core and overflow also. Thanks again , gary r

Yeah: Start the car with air conditioner and heater and defroster all turned off, watch the temperature gauge rise, as it passes the normal temperature it runs at while on the highway with no traffic, it should eventually turn on the fans to control the temperature. If it doesn't and keeps going to the danger zone, then you've found where to look.

The overflow won't tell you much. Get the temperature from the upper and lower radiator hoses. My opinion: If my fan test (above) shows fan problems etc. then checking radiator inlet/outlet temperature will tell you something you already know (that the fans aren't removing heat from the radiator). If the fans are working properly, checking radiator inlet/outlet temperatures will tell you how plugged up the radiator is and/or how stuck the thermostat is.

Thank's again , you are helping me very much. I drove it this morning and in traffic it heated up after about 20 min driving. The heater blows very hot with plenty of force. I use it to control the engine heat. My gauge is arranged with a mark at what im guessing is about 180 then at 200 with a large space to the 280 mark. I try to keep the temp below 200. Would it be normal that the car would operate above the 200 mark without being to hot? When I first got it the temp never got to 200. I have changed the water pump a couple weeks back. It is working good I believe. I hate asking all these questions but it has helped me greatly, thank you for taking time out of your day to respond. gary r

The main fan should come on at about 220* F. The pusher should come on with AC request.
https://cimg8.ibsrv.net/gimg/www.gmf...5a740d0666.jpg

What carfixer007 said ^^^^^^^

I'd call this "normal" . These gauges aren't horribly accurate compared to actual temperature and/or to other gauges in the same year/make/model of car. They are accurate as a reference to "normal" on the same vehicle. If it used to not ever exceed 200 on the gauge, that's probably because everything was working properly. When you fix the problem, I bet it will go right back to less-than-200 again.