Overheating when engine is turned off

[Beluga]

Thanks for the great forum! First time poster long time reader.

Amateur question I think...

My 86 tercel is overheating when I stop the car. For example getting gas after driving 20 mi. or so, or after 30 mi commute. When i resume driving the guage drops back down. As an aside: during the 6 mo. I have been driving it, I notice the temp gauge is sensitive to conditions: going up a grade for a few minutes, the guage will climb, but not into the danger zone and when I switch on the heater it drops back down almost immediately.

Has anyone else encountered this?

Thanks!

[Highlander]

I had this when I first bought the '85 sunroof- turned out to be a plugged radiator. The car came from a ranch in Wyoming, so I assumed that they'd refilled the radiator with creek mud. bought a new rad- runs just right on the gauge. Try flushing the rad out first-its cheaper

[Petros]

Welcome to the list!

IT is operating like it has limited cooling capacity, or the cooling fan is not working. when idling when not moving do you hear the fan kick on when the temp gauge gets above half way? If not it could be the sensor (in the bottom of the radiator), or the fan itself. to test the fan, unplug the sensor and the fan should come on full time.

IF the fan is working properly than it has a plugged up radiator and either should be power flushed or replaced if it old.

where do you live? Getting either a cooling fan, the thermal switch sensor, or a new radiator is going to a lot less costly from a wrecking yard if you have one near by. The radiator, sensor and cooling fan are common to the 2wd hatch back version of this car was well, so it should be easy to find used. The fan and senor are pretty reliable, so getting a used one is a good bet. Radiator is random luck if you get a good one.

[Beluga]

Yes, the fan does kick in while idling, so i guess I'll take your advice and start with the flush. You think that the temp sensitivity I mentioned related to this as well? What would a "power flush" involve? Thanks for the sage advice, its great to know there are others who really appreciate the awesomeness of the Tercel.

[dlb]

a power flush is something like this:

http://www.prestone.com/products/car_ca ... treatments

you just drain a bit of coolant from the rad, add this bottle, drive the car for a total of 3 hours or so (over a few days if need be), then drain the rad. fill it with hose water, let it idle for 15 minutes or so, drain it again. at this point you should fill it with coolant and deionized water (or the premixed crap) but i would fill it with hose water while you test run it for the next day--if you still have the problem you'll just have to throw out the contaminated coolant when you replace the rad anyway. a day or two of hose water for coolant won't hurt anything, just don't leave it in there for longer.

[Petros]

If you have not replaced the thermostat do it NOW! they are notoriously unreliable. Do not by the cheap one, get the premium brand, NAPA gold, or the Autozone premium (about $16-20), or a factory Toyota one. The cheap ones do not last and are often junk right out of the box. A t-stat that does not open all the way will act just like you describe. Use gasket sealer or RTV to hold the new t-stat in the housing as you install to make sure it stays seated properly, it is easy to misalign the new t-stat and create a big leak.

If the problem is the radiator all scaled up there is one thing you can try. I have taken other wise scaled up radiators that will not cool, removed them and filled them with hydrochloric acid (sold as "Muriatic acid" in hardware stores) for about an hour and than flushed them out with hose, added baking soda to neutralize it and than reinstalled it. If the radiator is all corroded it will like eat through the remaining metal and leak, that means the radiator was junk anyway (corroded and scaled up), if it works to remove the build up in the radiator it will save you from having to replace it.

This is a "do or die" treatment, so only do it if you are sure it is the scale in the radiator is the cause, and be prepared to replace the radiator if it fails. You will be etching metal way from the inside of the radiator. The scale build-up is a real problem that many dismiss, I had to replace an other wise good radiator in my wife's MPV that was literally plated with scale from too much tap water put into it. The acid treatment would not even touch it. Buying distilled or filtered water is far cheaper than replacing the radiator.