Heat Problems

deerchooper · November 18, 2009

well my new/used truck started to have issues. i was driving home today and noticed the air coming out of the vents was cold with the temp set at 80. i cranked it up to 90 and it got hot again so i turned it down. its 55* here today. i got to the shop/ office and shut it off to do some things, loaded a quad and headed home. i felt heat again and it was set on 80 again, so i started to pay attention and as i drove it got colder. about 20 minutes later it felt like the ac was on. i got home and let it sit for some time and poped the hood. looking for a dam radiator cap is worthless on these new rides. i checked the over flow bottle and it was full to the cold line, as i turned the cap off i got a little bit of pressure out of it and that was that. also before i shut it off i threw it into park and gave it some gas to get it around to 2500rpm, i felt some heat but it wasnt great, acts like its low on fluid.

i called the gm dealer i bought it off of and they went into the story we only gave you a power train warrenty, i said you didnt give it to me, gm did. ive had it for 2 weeks and you cant take care of it i asked. i have to call them tomorrow to talk to another guy.

what do you think it might be?

i didnt see any milky oil on the stick. cant check the rad if there isnt a cap on it. it might have an air pocket in it, i dont know. i dont want to deal with this threw out the winter, i drive 3hrs a day to and from work and i want heat.

96chevy7.4L · November 18, 2009

That cap you twisted off that had pressure in it was your radiator cap. That is how the newer trucks are. If the engine was up to operating temp. then you should have seen the coolant up to the fill hot line. If you want to check it for air just leave the cap off when its cold and let the engine sit an idle till it warms up and the thermostat opens. Once it opens it will bleed the air off if it has any. Then simply fill it to the hot line. But make sure the thermostat opens before you put the cap on other wise air may still be trapped.

deerchooper · November 18, 2009

the cold fill line is at the top of the bottle. the hot line would be higher right?

jrod332 · November 18, 2009

It may be your thermostat.

bigfat66 · November 18, 2009

maybe blend door motor i am having same probelm put thermostats in it still doing it so my shop is going to put blend door motor on it

deerchooper · November 19, 2009

what kind of temp are you guys getting with the 6.0?

i noticed to day if i had it on auto heat it worked great, 3 hr test. once i got a little hot i backed it down to 76 to 79. still some heat, then when i went down to 75 or so it was cooler. which i think that is right. 90 is just stupid.

rodram · November 19, 2009

... hate to be a pessimist, but if it continually gets air in the coolant system you may have a head gasket leak (exhaust to coolant) ... had this happen to me once out on the highway when it was -30* (at that temp it doesn't matter much if you are talking fahrenheit or celsius.) you get a air lock in the heater circulating system and no warm coolant to the heater core.....

... could be just the thermostat acting up ... if they crap out then the coolant never really gets a chance to warm up properly... you'll get some heat but pretty limited...

... with respect to warranty, I bought a used 2006 car from GM this past summer and it still has a full warranty for another few months until january.... and if it is the engine (head gasket) I would think it would be covered under the 'powertrain warranty'..... talk to the dealership manager