thermostat problem?

[Rebel64]

Little to no heat output, and fluctuating temp guage in my truck.
Really sucked with this -3 crap goin on right now. Brrrrrrr.

[Turk]

Damn thats frigging freezing,sounds like a frozen thermostat.

[Rebel64]

Frozen? I didn't know they did that. My garage stays around 40-45, so it's not like the truck sat out all night.
I thought they either worked or they didn't.

[Turk]

Sorry I was just being humorous.

[Rebel64]

LOL ok...I need more coffee....not quite awake and with it here yet.

[badmaners]

Good morning. I think automotive thermostats are designed to fail in the open position. Otherwise you would overheat pretty quick.

[Rebel64]

There was a couple times the needle started climbing up pretty fast, then would drop back down eventually. When it dropped back down, that's the only time I was able to get any heat out of the vents.

[badmaners]

Only other thing would be the water pump. I'd change the T-stat first though. Sounds like it was closed in order for the temp to rise then opened to let fluid into your heater core. Just my .02$

[Rebel64]

Ok thanks for your opinion. Guess I'll stop at Autozone after work to pick one up. Hope this is a quick fix!

[BIG_T]

Sounds like either a malfunctioning thermostat, or possibly a cracked head gasket. How much does it fluctuate? See if there are bubbles in your radiator.

[Rebel64]

It just slowly kept creeping up getting hotter, then when it backed down I got some heat.
In the 30 mins it took me to get to work, it climbed up 2-3 times.

[OnlyPolaris]

on our old work truck the temp gusge would alwasy go up but when you gave it gas to cycle the antifreeze more it went down. eventually got it looked at and it was the thermostat. it is a 94 chev.

[cd]

while you are doing it, unhook the heater hoses from where they go into the firewall and take an old garden hose cut in half, hook it to the faucet then take the cut off end and stick on one of the outlets and clamp it on, then take the other half the hose and put on the other outlet on the firewall and point in a safe direction, then turn the faucet on full bore, works miracles for cleaning out the heater core and it doesn't really cost anything. Oh and on them chevys I always had a buddy give them half throttle while I top of the antifreeze and put the cap on, dunno if its better but I can get more antifreeze in. and yea try a t stat

[Rebel64]

Well here's the update.

Opened up the hood after getting out of work, popped off the rad cap, nada....nothing in the overflow bottle either.
Drove it to the nearest gas station and bought a gallon of 50/50. Added about half the bottle while the engine was running, closed it, came home, and things seem to be fine. Went back out there a while ago and started it back up, and added the rest of the gallon jug into the system.

I really should get my head outa my butt and check this stuff more often.