So when it very cooled out I just can't get interior heat. My thermostat is fine. should i just block off the front of the radiator for the time being until winter is over. is it a good idea. will it hurt anything?

 

how do you know your thermostat is fine?
what temperature rating do you have? 195 I hope?
when do your fans come on? like stock? not with a manual switch or always on with ignition?

 

I think the thermostat is fine because in summer it reads normal operating temp. its very cold here in chicago and my temp gauge is way low with lack of interior heat. when the car sits the temp will rise and interior gets warmer.

 

How far do you drive it?
Its just as cold here and I drive 22 miles one way to work and my gauge never gets over 160ish in a newer car due to it being that cold. And when it sits still it also gets warmer, but if I drive it short distances, 10 miles or less it appears its not getting warm enough, but its the fact it has to overcome this wild difference in where I want it to be and what it is and my stat and system was redone before winter.
Its just a fact of what happens when you live in the cold and yes blocking it off will raise it some, but seems to me it won't be enough.
195 stat is certainly needed, a good clean system, fresh antifreeze less than 3 years old and a known heater core that is not partially plugged or hoses that are worn and could be limiting flow.

 

block it, why you see big rigs with cover on theirs in the winter with only about a 1/4 of it getting air.

very typical in the extreme cold we are having right now of temps near 0

 

just finished blocking it went for a drive and boy o boy. im back to normal running temp for these chevy 350's I got nice warm air coming threw my heater. big change from were i was.

 

How is your heater hooked up? Have you checked your heater valve? With a properly working 195 thermostat, theres no reason to block off the radiator. In essence, the thermostat will do that for you by closing down and limiting the ammount of coolant flowing to the radiator. I suppose if you where in antarctica you might need to, but in most conditions, it shouldnt be necessary.

When the heater is properly hooked up, the coolant feed to the heater core comes right from the block, so if you have a good t-stat, youll have heat.

Im running my car with working air ducts in the front and an oversized air dam, and Ive never had heating issues even at 10 deg F.

 

sounds like your thermostat is stuck open. happened to my wifes car last winter. did the same exact thing. in the summer it will seem fine because it will always be open. in the cold winter it never closes so it is always circulating freezing cold water through the heater core. when the car sits running you will get warm air because the radiator is not being hit with the freezing cold air. i would replace the thermostat with a higher temperature rating, it is a very cheap part.

 

I think I have a similar problem, car never seems to warm up, which is usually not a problem here in texas, but this time of the year it can be

I took my radiator cap off and looked at it right when I started up the car today. the water wasn't circulating, whihc tells me the termostat was in the closed position. I'm not sure how long I would have to leave it running like that before I would actually see it circulating

 

it would start circulating @ about 180ish to 190ish depends on stat.
this interesting i removed my stat and my engine got rebuilt and even in the winter (its like 2deg around here) warms up in about 10min of driving or 20ish min of idle and my fans are set to 160deg and never passes that. and my rad is a tri core for extra cooling capability.