Car won't heat up during winter time.

[rms1390]

I have a 1993 240sx hatchback it has an intake system and a Isis radiator. So when I start the car I let it run for more than 10 minutes but still the tempature won't heat up. Even when I drive it it still won't heat up. Though when I stop for a little bit the car heats up for a little bit according to the gauge. So I was wondering if there's something I need to do. Or get a thicker oil I need to use? I have already bleed the radiator for air. Changed the antifreeze and all of that.

[kouki munster]

Is there a thermostat in the engine? If not put one in it and repeat bleeding the air out of the system. If there is it may be an issue of over cooling, use some cardboard or plastic to block off 1/4 to 1/2 of the radiator to see if it will build up a little more heat, just be sure to take out said cardboard/plastic when the weather warms up. My Sr swapped 97 has this issue, without most of the radiator blocked off it will not get above 160* during the winter, even with it blocked off it still takes 15-20 min to get something other than cold air out of the vents.

[rms1390]

During the summer the temp. is normal so I think it does have a thermostat. But I will give the cardboard thing a try.

[ricebike]

don't AsSume that you have one... actually check if there is one!

also if you got a t-stat in the housing, it may have been stuck open

i had one of those failsafe t-stats and if it senses an overheating condition, it'll stay open all the time after that condition presented itself...

another thing to check is to actually feel those 2 small heater hoses going to your firewall and into the heater core & see if they are warm/circulating

[float_6969]

Sounds like a stuck open thermostat to me.