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Radiator Fans

683 Views 8 Replies 6 Participants Last post by  nurburSTIG
I replaced the radiator in my '89 si last night and as I was bleeding the system I noticed that the radiator fans never came on. The car was idling with occasional throttle blips for about 15 minutes. The temp guage on the cluster showed the needle about 1/3 of the way up from cool. I've only had the car a couple of weeks, so I'm honestly not sure how long it should take for the fans to cycle. At what point on the temp gauge should they come on? I'd take it for a drive to test, but I don't have the front bumper or hood latch on the car right now. Also, cycling the AC on did not turn on the fans.

Thanks for the info!
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It takes a while. When my new engine was just in, we started it up and waited until the fan came on to make sure it worked. I think it took nearly 20 minutes.

The stock temp gauge sits in the same spot over a large range of safe operating temps. If the needle starts to move up to the halfway point or more before the fan comes on, then you can worry.
My '90 Si fans don't seem to come on neither. I haven't driven it for a year and finally decided to get it back on the road, so I don't really remember if the fan ever came on before. Temp gauge always stays about a 1/3 up as well. It's also a cold November in Canada.

I drove the car for about an hour straight today, and when I got home I popped the hood to see if it was on. Doesn't even look like it had turned on at all because it was still dusty. Any ideas. Is it bad for the car if I wait until Spring?
just keep an eye on the temp gauge. it's not bad unless the temp goes high. if it's really cold and you need some heat, use a piece of cardboard to block off part of the radiator.
you can test the circuit anytime by using a jumper at the temp switch...if the fan doesn't come on you'll need to repair something
Thanks Z
We're expecting a really, really cold winter this year and I could use the extra heat. I've seen folks put cardboard in front of their rads before, and I used to think to myself, "Is that safe? Wouldn't the radiator get hot enough to burn the cardboard?" Am I just being paranoid?
the radiator won't get hot enough for it to catch fire. it may get hot, but it will never burn. i used to wedge my cardboard between the radiator and the T-bar/hood support.
i left a gap on the fan side just in case it ever came on, but in really cold weather it's not an issue.
Water boils at 212F and with ethelyne glycol, it changes the boiling point depending on your mixture but that additive also keeps your block in good shape in the winter as the freezing point of water is lowered.
Now if you want, look up the flash point of cardboard. :)b
Ummm... so I finally had some time to place cardboard in front of my rad. I've wedged it right in front of the rad without a gap. The whole surface of the cardboard is touching the radiator. I haven't driven the rex yet.

SAFE? I see that the flash point of cardboard is approximately 200 degrees C (392 degrees F). Bio mentioned water and ethelyne glycol boils at 212F.

Any thoughts on a better place to put it and how? ...I really don't feel like taking my bumper off again. Like really, really.
Cardboard flash point = 195 degrees Celsius = 383 degrees Fahrenheit
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