Thanks for reading my post, my son has 01 Saturn SL2 with 115K on it. We just replaced the radiator due to a crack in the plastic housing. I got to thinking that maybe the reason for the crack is because the engine ran hot at some point although my son says the gauge doesn't run high.(I don't trust his vigilance) The water pump and thermostat were changed two years ago so I know they're fine. I have been watching the fan to make sure its coming on but have not seen it engage during normal operation although its only been 40 degrees outside the last two days. I'm wondering how high the temp gauge will go before it tells the fan to kick in? Ive taken it up to just a hair above halfway on the gauge with no fan results. So a friend shared with me a tip to disconnect the temp sensor connector which I did and the fan came immediately on. Does that mean its likely the temp sensor itself that's possibly bad? I also was told that on most cars, simply turn on the defrost and you should see the fan kick in but I tried that (the engine was cold) and there was NO fan operation. Thanks for offering any feedback, I might be worrying about nothing and the car's just not running hot enough to witness the the fan get energized. Dale

 

The crack in the side tank of the radiator is due to heat cycling and age. Was the location of the crack near one of the radiator supports? It usually is. Not directly attributable to overheating.

Why is anything else necessarily wrong? The cause and effect is not always necessarily failure of one part causing the failure of another.

I do appreciate your desire to know that the fan is operating as it should.
The temp gauge usually rises to the 3/4 tick or approaching the bottom of the red and then the underhood cooling fan kicks in. The temperature gauge needle will usually drop below the one half mark at which point the fan will turn off. This is controlled by the resistance of the coolant temperature sensor which changes with temperature.

You've determined that the fan is functional by removing the pigtail while the vehicle is running.

The cooling fan should immediately turn on and stay on when the air conditioning engages. The compressor needs to be running for this to occur. For example, if the system is low on refrigerant and trips the low pressure switch, the compressor will not run and the fan will not engage.

The only thing left to do is to either confirm the temperature at which the fan turns on via the diagnostics port or let the temperature cycle up until the fan does turn on. It is a bit unnerving the first time that you watch the gauge rising that high, but welcome to owning an S car.

 

Thanks for the reply Derf, I didn’t realize the temp gauge had to run so high to energize the fan. I might just change the temp sensor anyway since it’s relatively cheap and easy to do for a 24 year old car. I need to examine the plug for corrosion on the contacts as well. Thanks again.

 

It is very common for many manufacturers radiators to crack the plastic tank near the hot hose. They can only take so many heat cycles. There may be nothing else wrong with your car other than heat cycles.

 

Thanks, I agree.
Plastic might have its place in certain applications but I feel that in the case of a cars radiator tank, that was a bad design flaw. I’m actually surprised it made it 24 years before it finally cracked. Saturn wasn’t the only one using plastic on major components. My Mercury grand marquis has a plastic intake manifold and they were known to be a weak link over time.