I have a 1994 Saturn SL and ever since I bought it a few years ago it has been overheating in traffic but does just fine when I am driving without the stop and go. About a year ago 2 of the cylinders blew and I had to spend $700 to replace the now shot motor with a rebuilt one. Well the engine still heats up. I tried replacing the cooling sensor a few weeks ago and still no change. It really sucks because the only thing that keeps it from totally overheating is if I put the heater on full blast. And considering it’s almost summer I really want to get this thing fixed. Using the A/C only makes it overheat worse, and will make my engine stop if I keep it running while stopped for a few minutes at a time like at a stop light.
This symptom is almost always from a cooling fan that is not coming on. The reason it is fine while just cruising along is that your movement is forcing air over the radiator. So you need to find out whether or not the cooling fans kick in when they should. You can check the fan itself by jumpering directly to the battery to see if it goes. If the fan does go when you jumper it, then you need to check its wiring harness and then on to the control side (e.g. relays).
Well they said that was the problem when I had the sensor replaced. They said it wasn’t kicking on in time to cool it off. So replacing the sensor was supposed to fix it…
This also could be due to a partially clogged radiator. If the fans are working, you may need to flow-check the radiator.
After they replaced the sensor, did anyone run the car to make sure that it was fixed? This isn’t rocket science. When the car is up to full temp and hits a certain temp (probably 240 coolant temp) the fan will kick on. It’s hard to miss it if you just check for it, and if you were told that was the problem then someone should have verified the repair.
Well I didn’t bring it to a shop. I know someone who’s a mechanic and has successfully repaired quite a few cars so I asked him for help
If you get the car up to operating temp and the fans don’t come on at idle it can be the temp sensor which you replaced or the cooling fan relay. If you car starts to overheat, switch the cooling fan relay with another one with the same number on it. If your fans come on then, just buy a new relay.
Let’s back up a bit. Your car had an overheating problem, likely it was the overheating that either caused or contributed to the engine “blowing” a year ago. The engine was then repaired or replaced, and yet the overheating was never fixed. No sane shop or person would let the car go after the engine repair unless the overheating problem was fixed and verified. That would be like a lung cancer patient stopping for a carton of cigarettes on the way out of the hospital.
Your problem sounds like a radiator fan not working properly. This is easily checked and fixed on your car by a shop or mechanic with a wiring diagram and the basic scan tool to hook up to your engine computer. It may be something as simple as a fan motor that’s gone bad.
Take the car to a shop that has the equipment to work on your car and have it fixed, or you’ll be buying another engine.
Do this first, start the car, turn on the AC, open the hood and see if the fan is running. The fan should come on whenever the AC is on, whether the engine has warmed up or not.
If the fan is not running, then either the fan relay is bad or the fan motor itself. The next step would be for your mechanic friend to apply 12v battery directly to the fan wires to see if the fan runs. The quick way to do this is to jumper the fan relay socket. If he doesn’t know how to do this, post back.
Have you done a pressure test on the cooling system?