A few cooling system questions Options

[ActionClaw]

(1995 Toyota Celica ST, 1.8L 7A-FE)

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?

Thanks

[travisxcore]

To confirm its circulating you can:
A) Listen to hear if the thermostat opens/closes, its right under the alternator (Its in a cast aluminum pipe that goes to the radiator hose there)
B) Buy some UV dye, run the car for a few and pop off the hot side hose after it cools down and take a UV light
C) Feel/watch the hoses

Is the car running too hot or too cold? Cause it could just be your thermostat. They can get stuck open/closed (they have a bleeder valve in them so a little coolant always flows regardless)

For the fans, turn the car on and let it idle. They'll kick on after a few minutes. Your temp gauge should be about dead center when its at the currect running temp. No need to drive the car around.

This post has been edited by travisxcore: May 15, 2013 - 5:38 PM

[Galcobar]

Toyota wires its fans to run, unless the temperature switch for the fans -- it's mounted on the radiator -- turns them off. It's a safety protocol, so that if the temperature switch fails the fans run constantly.

You can test whether the fans run by starting the engine, then unplugging the temperature switch for the fans. If they start, then the fans are good. If not, check the cooling fan relay, cooling fan, engine main relay and fuse, and check for a short circuit between the cooling fan relay and water temperature switch.

If the fan switch is working, the fans will kick on at 93C. You can test the temperature fan switch with a pot of water, a thermometer and a continuity tester. At 83C and below, there should be continuity between the terminals; at 93C and above continuity should be broken.

As for circulation, travisxcore's suggestions are all valid. The upper hose carries coolant from the block to the radiator, while the lower hose returns coolant from the radiator, through the thermostat, to the block. There should be some temperature differential. If the hoses get firmer with the engine running, the system is pressurizing. The thermostat will open at 83C, by the way. However, the simplest method to tell if your cooling system is circulating is the check the temperature gauge. If the coolant does not circulate, the temperature will climb beyond the halfway point.

[ILoveMySilly97]

Coolant flow is really noticeable. With the radiator cap off. You can look and see the coolant flow. it'll flow fast enough to where you'll see it ripple over each other like a waterfall does.

For the fan. Run the car on idle. The fan should kick in about 15-30 min or when engine reaches correct temperature.

Most of the time the fan kicks in the same time as when the thermostat opens which causes coolant flow.