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Engine Staying too Cool

5K views 8 replies 4 participants last post by  FormulaDz92 
#1 ·
Ok first off I did use the search button and although there were threads on engines not heating up none matched my problem specifically.

My car: 1989 Nissan 240sx with a 1992 KA24DE engine. Mostly Stock

A month ago I decided to do a complete AC Delete since the last guy had already removed the compressor. I gutted the AC box behind the dash, removed the condenser, evaporator etc. To remove the condenser I had to pull the radiator so at that point I flushed the fluid, bled everything and pulled off an electric fan that the previous owner had installed just to simplify things for now.

As soon as I started the car up and drove it I noticed it was taking forever to heat up. If I let it sit in the garage(its pretty cold outside) it warms up to operating temp after 15 minutes however as soon as I begin driving the temp plummets. I know what you're thinking; this guy has a thermostat that is stuck open. Seems reasonable but the timing of the problem seems too weird. Why would the thermostat stop working as soon as I flushed the coolant? I personally think it has something to do with my unplugging the aftermarket fan.

Any help or suggestions are welcome

*one important bit if info is that my lower radiator hose has clearly been modifies and looks like this :
https://www.google.com/search?q=s13...fan-controller-optional-t368144.html;1024;768
Also I didn't see any relays that were powering the fan.
I realize another possibility could be a bad thermoclutch or whatever it's called on the belt-driven fan.

Thanks again. :smile:

Just trying to get ready for rallyX in a couple of weeks.
 
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#2 ·
Even if the Fan Clutch was bad and "Locking" the whole, it's just the part that cools the coolant. The Thermostat is the temperature control.
It more than likely stuck open.
Our Thermostats Suck, and They are a Bitch.
 
#3 ·
Thanks for the quick reply. It's just weird that it worked perfectly, I changed my coolant, disconnected the electric fan and now it can not hold its operating temp. guess its time for a new thermostat then.
 
#5 ·
So I finally got around to pulling out the thermostat. Turns out after pulling off the rad hoses and the housing, there was no thermostat in there at all. I can't believe it was holding a temperature before without one. New rad hoses and thermostat go in today. Hopefully no heating problems and I can rallycross the car on Sunday.
 
#8 ·
Good news, I've been driving my car normally for a week with the thermostat in with no issues at all. It warms up within a few minutes and holds temp well under reasonably rough driving. Haven't had a chance to try it in a race setting because the rallycross event was canceled due to muddy conditions haha. My guess is previous owner was a cheapo and when the old thermostat stopped working he just pulled it and didn't replace it even though they're only $20

I went with the 170 degree thermostat btw instead of the 180 degree one.
 
#9 ·
Just one last update. I've been driving the car on the highway in eighty degree weather as well as around town with no overheating issues still. Only problem right now is the rust... and the tachometer doesn't work.
 
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