A few cooling system questions


Old 05-15-13, 02:31 PM
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Join Date: May 2007
Location: USA
Posts: 52
A few cooling system questions

(Mostly general question but car is 1995 Toyota Celica ST, 1.8L 7A-FE, 5-spd)

I had some cooling system issues. I believe I may have found and repaired the problem but while looking I noticed a few other things that got me thinking.

How can I confirm that the cooling system fluid is properly circulating?

Some say to run the car with radiator cap off and look for movement/turbulence. I see little to no "flow" or movement (in this or other vehicles). Any movement I do see seems more likely to be caused by engine vibration. What is a better testing method? Is inserting a thermometer into radiator and simply watching for temperature increase sufficient?

How to determine if electric radiator fans are properly functioning?

I've found info regarding other cars that fan operation is controlled by multiple sensors: engine temperature sensor, cruising speed, whether the AC is on or off, etc.

I'm guessing a simple enough test might be to drive the car a while, when assumed hot enough, stop, pop the hood and visually check whether the fan is running but because I was unable to have the emission test done, the car currently can't be legally driven. Will the fans kick on at idle and, if so, approximately how soon after starting (cold)? Suggestions?

Thank you
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Old 05-15-13, 11:54 PM
PJmax's Avatar
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Join Date: Oct 2012
Location: Northern NJ - USA
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because I was unable to have the emission test done, the car currently can't be legally driven.
Why is that ? Here in NJ we are issued a pretty red sticker for our windshield and are given 30 days to have repairs made and re-inspection done.

If you don't have proper coolant flow your engine will over heat. There isn't always a way to confirm it. Sometimes it's hard to confirm flow thru the radiator by looking thru the cap.

Electric fan(s) cycle on and off based on engine coolant temperature and demand from the AC system. While your engine is idling......it will get hotter and at a certain point the fan should come on. Usually you can determine the turn on point while watching the temperature gauge.

Also.... the fan(s) should cycle on every time the AC compressor engages. Have your car idling..... turn on the AC. The fan(s) should immediately come on and will cycle off when AC is satisfied.
Old 05-16-13, 03:31 AM
Join Date: Feb 2013
Location: United States
Posts: 197

More detail is needed here before you can be helped. In other words you state that you had some cooling system issues, and that you believe you may have found and repaired the problem. Well what exactly were the issues, and exactly what repairs did you do?

Thank You

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