Its -25 and my trucks colder than a deepfreeze.
The engine seems to heat up to temp according to the temp guage but it stays barley warm enough in the cab.
It will warm up some when driving it but when its idleing it never warms up.

 

It's the nature of a diesel engine not to warm up while idling, in fact extended idling will cause damage.
When it gets really cold the only way for me to get heat is to use the recirc position of the climate dial. Cold outside air passing though the heater core just doesn't warm enough when it's -25°. Recirculating the cab air will do the trick.

 

Thanks Bill I should have mentioned its a 1991 1 ton so the heaters pretty simple.
No climate control.
My Ford diesel will get so hotin the cab just sitting that you cant stand it.

 

Get one of those cold-weather fronts or fabricate your own to block the airflow through the radiator.

 

Check for the posibility of a thermastat that is stuck open, my understanding it should be closed from radiator cooling until the temp reaches a decent operating temp then would open only for cooling to that temp, if astuck open engine cannot build heat. But the Engine temp guage should not be climbing up to normal temp.

Also under Dash is there a heater water flow valve or any vacuum actuated gates or doors that may not be opening??? (question for everyone)

 

You may also want to check for a blocked heater core.
Disconnect teh heater lines going into the core on teh engine side of the fire wall. Place a agrden hose on one of them and see if you can push water through it. Also check the hoses. Sediments can build up in the core and if blocked , it will not ciculate.

Longhorn, post your truck info in your signiture so when you have a question, everyone can see what year truck and what tranny, mods ect.... makes getting help much simpler....

 

My truck did the same thing since the day it was new. Always thought it was just the nature of the beast. About a year ago, I changed the thermostat. I can't actually remember WHY I changed it, because like yours, the gauge always read in the 'normal' range. But after changing it, I now have decent heat all the time and at all outside temperatures.

I should add tho, that about 6 months after changing the thermostat, the heater core started leaking. Don't think it was related, but none-the-less, strange.

chaikwa.