Well where to start. My father in law has an 89 formula 305 tpi. He parked it 5 years ago because he said it would overheat and the cooling fans wouldn't kick in. So earlier this year I got tired of seeing it sitting under a car cover and rotting away so I decided to see if I could get it running. I charged the battery and it fired right up. Even with that old nasty gas. And after letting it run it gets up around 190 degrees on the gauge and the cooling fans don't come on but if the ac is turned on both fans come on which tells me the relays are fine. I've read a bunch of posts and I'm kinda confused as to which sensor is bad. I'm guessing its the sensor that's in the passenger side head but I could be wrong. He doesn't want me to mess with it at all. He just wants it to sit in the barn and rot away or sell it to someone how will pay $5,000 for it. So I'm going to do the work I just don't want to put too much money into it with it not being my car. So if someone can point me in the right direction that'd be great. Thanks in advance.

 

The primary won't kick in till the temp hits 230-235.

 

I thought it was 220-225?

 

If the fan relays are in working order then possibly the temp sensor is bad.http://tpiparts.net/inc/sdetail/10956/497

 

Replace the sensor on the passenger head and then see what happens. Do not expect the fan to turn on at any temp in 220 or so. These cars were designed to run hot to burn off hydrocarbons to reduce emissions. The sensor on the drivers head or the intake, is what the gauge uses to get its temp reading from. Just an FYI.
If the gas has been in the tank for a while then I will remove it and put fresh gas in before you go and start this thing anymore. Make sure there is no mice or other small animals living in the intake duct work and filter. Change the oil too and make sure the coolant is in good shape. If the car has been sitting that long then you will find more problems along the way like dry rotted vacuum lines. look the engine over very good before you go and continue messing with it.

 

If the car is a dual fan set-up, the switch in the pass head is for the pass. side fan and wont kick it on till around 235 degrees or so. This is the back up incase the primary fan(driver side fan) fails to turn on. The pass. side fan will only turn on if the temp reaches 235 degrees or so and also when you turn on the AC, which will turn on both fans. The rest on the time, it stays turned off. The primary fan(driver side fan) will turn on when the temp reaches about 220 degrees. The coolant sensor on the front of the intake and ECM control primary fan operation. This sensor also tells the ECM what the engine temp is for fuel calculations and other stuff. Thats where I would look if the primary fan isnt turning on when it should. Could have a bad connection or broken wires or a bad sensor itself. There is also a sending unit on the driver side head in between the first 2 spark plugs that controls the gauge. I would make sure that the car is indeed overheating before replacing anything. Most people think the car is overheating when its actually not. They just dont give it enough time for the fan to kick on and when the gauge hits 220 or so, they think its overheating. Most of our cars, the temp gauge doesnt read correctly anyway. Like bottledz28 said, our cars are designed to run hot for emissions.

 

 

230 seems high to all of us but GM must have done a lot of research and if they set the fan to turn on at that temp then they knew it wouldnt damage the engine. Loosing HP on the other hand wasnt their biggest concern. Burning off emssions was when the EPA was watching over them.

 

It is what it is.That's the way it was designed to run.

 

Thanks for all the places to look. I tried to drain the old gas out of it before I started it but when I tried i couldn't get the drain tube down the fill tube. And I don't have any tools at their house and neither do they so I was limited on my options. It had a full tank also and is now down below 3/8 tank. I also don't let it warm up to 230 degrees so that could be why the fan doesn't turn on. Yesterday was the first time I let it warm up to around 190. The thermostat opened and I shut it off a couple minutes later. It's just too nice of a car to let sit and rot away. 78k miles bright red formula 5speed ws6 suspension 4 wheel disc brakes. And if I remember correctly that means it was a level 3 formula. I could be wrong. I don't know anything about these cars.