BOILING RADIATOR!

[kevyrev]

So the other day my son drives the festiva home from school and it was overheated and coolant was overflowing onto driveway. I replaced some coolant later after it cooled down and took it for a drive to take off trash. The fan is working and coming on, and don't seem to find any leaks so, I'm wondering what is happening. When I replaced some coolant, I noticed that some of the old is rust (muddy) colored, as well as the coolant that came out on driveway while it was overheated. Do I need to flush system? Also when I took it for a drive the temp gauge was going too close the hot but didn't overheat.
So he came home today and it was a little steamy and the overflow tank was boiling.

[ryanprins13]

How far are each of these drives and how warm is it where you are? All in town or highway?
Its probably a thermostat stuck shut or plugged rad .
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[kevyrev]

It is a fifteen minute drive in town. Temp is in the mid 80's. Seems to be some particles of sludge floating around when I fill new coolant to the neck of radiator. Should I flush the radiator and I'm guessing to get a new T-stat?

[ryanprins13]

Ok. Well once it gets warm feel the upper and lower rad hose. If they are hot its not the thermostat.
If thats the case flush everything real good more than once with that cascade detergent and then either try that or get a new rad for $70 or so.
If you really want to reuse yours maybe take it out after the cascade flush and flush it with muratic acid and water, neutralize it with baking soda and water, flush with water and then reinstall.

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[WmWatt]

When in doubt I like to consider from low cost fixes to high cost - flush system, thermostat, water pump.

[ryanprins13]

Dumb question but how is your belt? Tight enough? How does the waterpump pulley look?

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[kevyrev]

So today I opened drain at bottom of radiator and then put the hose to top and flushed. Looked like muddy water coming out. Filled it back up and went for a drive. Temp gauge never gets to H but gets a little past halfway and again as I parked after a 15 min drive coolant was boiling in the overflow tank!

[william]

On most festivas the fan will come on at 1/4 the way up, half way is really warm and over half way is way to hot.
Make sure your tstat is not sticking.

[ryanprins13]

All mine have had the thermostat open at half or just above, fan doesnt come on until almost 3/4 of the way up. This is with non-tach clusters but i dont think there should be that much difference.
And yes, i have verified with an IR gun an aftermarket temp gauge and another thermometer. That was when i was verifying the accuricy of the aftermarket gauge.
Kevyrev- just flush it out till the water is clean, then use that cascade detergent flush. Theres instructions on how to do it and how much to use somewhere on this site.
When you drsin the rad and then look in the top how does it look? All plugged up or ok?


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[kevyrev]

After I flushed it the water was coming out clean. Guess I'll pop in a new T-stat and see what that does.

[ryanprins13]

After I flushed it the water was coming out clean. Guess I'll pop in a new T-stat and see what that does.

But you just flushed the rad, not the whole system right?

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[kevyrev]

Flushed radiator, yes. I did start it and let it run for a minute and then more nasty brown coolant came out. Then flushed more and put plug back in, filled and drove. After 15 min coolant is boiling in overflow tank.

[ryanprins13]

Oh, boiling or shooting into it? It could be a bad radiator cap. It would let coolant into the overflow without much pressure and the coolant boils at a lower temp when there is no pressurre.

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[RobotKarate]

What kind of water are you using to flush it?

[WmWatt]

You can test the thermostat by putting it in a pan of water on teh stove and heating to see if it opens.
When installing the thermostat be careful it seats properly as peopel have reported here cracking the housing when tightening the bolts.
I bought one of those cooling system flush kits where you clamp a plastic garden hose connection in permanently.