today on my way home from work my car ( 90 civ hatch / 93 obd1 b18a) over heated and my heater never got even warm...its about 30 degress out....and my lower radiator hose is still cold as hell...

iam guessing thermistat...
any takers?

or what else could it be???

 

sounds like a coolant leak, but it wouldn't hurt to change the thermostat if the coolant level is where it's supposed to be.

 

Yes, thermostat and lack of coolant. Ryan

 

another thing that can cause you to over heat is using a larger sized temp sending unit other then OEM. It will actually block flow but sounds like your main problem is the thermostat isn't opening up. Take it out and let it free flow see how it reacts

 

it happened to me a few days ago
same deal
and my car goes to red and comes back down in matter of seconds
i knwo its a bad thermostat
but i also found my water pump its kinda dead
so i am replacing both today

 

Try to feel the top of the radiator when the car is hot (don't take the cap off though). If it is still cool and you still have coolant, then you know it is probably the stat.

I'm about 99% sure thats what it is anyhow.