Thermostat vs. water pump

[MIGHTY 8]

Hello all,

Is there a "quick" method of determining which of the two has failed? Or rather both at the same time?

My car began over-heating, and I noticed that the lower hose below the thermostat was cool (that one from the thermostat to the bottom of the radiator.) Lead me to believe it was a faulty unit in this case.

Secondary issues, the radiator fan did not "kick-in." Didn't touch seperate parts of the radiator to notice any differences in temperature, unfortunately, which might have helped in trouble-shooting.

Ordered both, just in case, and know that to change the thermostat is relatively easy, therefore plan it on being my first option.

Just thought I'd ask for some insight.

Thanks in advance,

G.

[kilrwail]

Sounds like the thermostat. If it had been the pump, you'd have heard it making some pretty ugly sounds, more than likely. As for the fan, disconnect the plug and apply 12 V to it to see whether it works. If so, your temperature sensor/switch may be faulty.

[manoa matt]

The thermostat is stuck closed. You can take it out and test it in a pot of water on the stove.

If you recently performed work on the cooling system there could be an air bubble in the hose just below the thermostat. Loosen the hose clamp and stick a thin blade screwdriver in between the hose and thermostat housing to let the air out.

[halg]

An air bubble below the external thermostat will have no effect on the operation of the thermostat. The temperature sensing is in the housing between the head outlet and the water pump inlet(where water always flows until the thermostat operates)
Hal

[redcars]

It could easily be that niether is bad if there is air in the system. This can happen if you have had any leak in your cooling system. To check this raise the front of your car then take the plug out of the tee on the front of the engine. Using a small funnel add coolent to the system. If it takes coolent you had an air lock in the system and filling back up with coolent will correct your problem with no parts needed. I found this out the hard way. Parts first and then got rid of the air lock.

[MIGHTY 8]

Can't thank you all enough!

I went ahead and ordered both parts anyway (Thermo. & W. Pump.) Just in case! I find that simply getting the parts needed is half the battle with these old cars!

I'll try checking for air locks, prior to "takin' her in." Hopefully will resolve the issue, and at best, I'll now have two spares to carry along with me on my next road trip!

Both these parts have been changed within the past three years, for what it's worth. And also not working in my favor, is the fact that the car sits for extended periods of time- 2-3 weeks at a shot sometimes.

Thank you all again,

G.

[Zippy]

Be sure to drill a very small hole in the thermostat before it is installed. This will allow the air to pass through and help avoid the bubble. Here is a link to the topic.
http://www.fiatspider.com/f08/viewtopic ... tat#p89903