bad thermostat?

[stant093]

so today i took my girls 95legacy up to my borthers to change the oil..well about 1000ft from my driveway, i noticed the temp gauge climbing awfully fast....then past the [H] for hot...i immediatly pulled over and shut the car off....i messed with the radiator, popped the top off, no over flow...-cold as can be for just starting it....so i tapped the thermostat housing..
..nothing...i started it back up and it was still there [above hot], knowing that the motor is not that hot, i put it in gear and moved about 10ft...then the gauge went to about 1/4 between [C] and [H], normal readings.
i stopped at the auto parts store and bought a thermostat and replaced it...seems to have fixed it...is this a sign of a bad thermostat? ive never had this happen to me..never seen a temp gauge move so rapidly....
tia
sam

[entirelyturbo]

If you say the engine wasn't as hot as the gauge was saying, then you might have a faulty coolant temp sensor, the one that tells the gauge what to do. But you said that it seemed to be fixed after the new T-stat install, so the engine probably was that hot and the T-stat was indeed stuck closed.

However, Subarus don't seem to like aftermarket T-stats, as I understand. Granted, that was an emergency situation, but what I personally would have done is taken the thermostat out entirely, let the car run cold all the time until I could come up with an OEM thermostat.

Is it also true that OEM T-stats are fail-safe, meaning that if they were to fail, they would only stick open, allowing coolant to reach the engine? Can someone confirm that for me??

[evolutionmovement]

I would only use OEM T-stat. Have you seen it? It's a big beafy typically overbuilt thing and the aftermarkets are flimsy and small. I have also tried the aftermarket one with no success. Didn't work for more than a week. Replaced with OEM and found out it was only a few dollars more anyway, and unlike Foreign Auto Parts, they didn't give me one for a Loyale (twice).

[ciper]

I always use an OE thermo. Reading storys about aftermarket units getting stuck close or binding up on the housing changed me real quick.

[Legacy777]

make sure you use an OEM. The aftermarket jobbers do not have the same opening rate, temp change rate, and other issues which will cause problems.

[nubs]

[quote="subyluvr2212"] but what I personally would have done is taken the thermostat out entirely, let the car run cold all the time until I could come up with an OEM thermostat.

quote]

Sometimes taking a thermostat out can also cause overheating.The coolant does not stay in the radiator long enough to dissipate the heat.

[stant093]

well i had to use a big A thermostat for now, as far as getting a OEM t-stat, well thats over 100miles away..it seems to be fine...ill find out tomorrow, or atleast ill know myself...thanks for the input though everyone!

[ciper]

Order it from 1stsubaruparts.com or subaruparts.com, then its only the walk to your mailbox!

[stant093]

i took the scooby for a ride today...about 40miles+ working fine, temp is actually a little cooler than b4...but i will put a oem t-stat on my to-do list...along with my impreza, and my LSi...i need a vacation!!

[123c]

Not having to much experience with the cooling systems in these cars, but after dealing with my MB diesel, I know to always use OEM t-stats. Can anyone tell me if they are hard to bleed all the air out of the cooling system? I know that in my MB it is very hard to get the air all the way out...

[entirelyturbo]

Until I realized that there is a air release valve on the passenger side of the radiator, I always just shook the radiator while I was filling it, and when it was full, shake it some more until no bubbles came out and also squeezed the top radiator hose to expel any more air before I put the cap on.