I usually pre-heat my car(remote start it) 15-20 mins b4 I leave so its nice and warm. I noticed the heat was ice cold yesterday, I reversed out of my driveway then it kicked in, I figured something was froze(it hit -20 below temps here in Cleveland).

Today same thing, even worse now heat came on only after I drove in access of 50mph(highway), also I noticed coolant on my driveway, so when I got to work I popped my froze a*ss hood and noticed a small amount of coolant right under neath the big upper hose,I squeezed it (car off) and there is no pressure built up in it, so what could it be?

 

either a blockage or a stuck thermostat.

 

Should I check pressure in the hose with it running, how do I know?

 

Just reread what you typed. It is most likely NOT a thermostat stuck in the open position. When the thermostat is stuck open, your car will run cooler than normal and will get cooler when you are going faster. your cars actual temp guage will drop. You sound like you have a severe restriction of your heater core (assuming the rest of your car is operating normally). The only thing that makes me think the thermostat is stuck is the presence of coolant "under the big upper hose". Need a little more information to diagnose it. Does yoru car reach normal operating temp? does it drop when driving fast? does it go above normal operating temp? The first thing you need to do is open up the radiator (cold car) and make sure there is coolant in there. You cant go by the level in the resevoir.

 

Actually cars temp while driving is normal, just the heat has been acting up, no matter Im taking it to a mechanic to care of my fuel filler neck, Ill just let him look at it, thanks anyway.

 

If the car runs @ a normal temp but you have no heat you have a blocked heater core. Luckily it is not completely blocked (the higher pressure pushes it through). The mechanic will most likely recommend you change the core....$$$$$. If you want an alternative solution you can ask him to backflush the system or you can run some Prestone Super Radiator Cleaner through it for a thorough cleansing. Either way, good luck.

 

Someone on here changed his core out a while back. Do some digging for it. Very helpful.

 

Ill check it out thanks guys

 

His name is "dallas..." something. Sorry for the lack of detail.

 

By what you guys told me and my symptoms I think its my heater core, Im going to wait till summer then Ill clean it out.

 

dallas' symptoms were a bit different. his heat never got hot at all. it seems you have heat under certain driving conditions.

to confirm heater core blockage check the temp of the heater core hoses with heat on full blast. if top is hot and bottom is cold, you have blockage in there. if they are both cold you have something else going on (perhaps air in the system).

lack of pressure in your upper hose and coolant on the driveway point to other problems that must also be fixed in addtion to any heater core issues. find the leak and fix it.

be sure to purge air from the system when doing any work (even if you're just topping off the radiator).

keep the reservoir topped off.

don't mix coolant types.

 

Where exactly is the heater core to check the temps of the hoses?

 

the heater core itself is located behind the stereo. you have to remove the entire dash to get at it.

but the hoses are inside the engine compartment and connect to fittings at the firewall. there's an upper hose and a lower hose. hot coolant goes in the upper hose, through the heater core, and comes out the lower hose. if the core is blocked, the lower hose will be cold, or at least much much cooler than the upper.

if you find blockage, you may be able to disconnect the hoses and do a power flush through the core -- but Dallas' core was so plugged that no flush on earth would clear it out. you really should find his photos - the thing looked like it was packed with white clay. he did a nice write-up on how to replace the heater core. pray you never have to do it.

 

Here it is I found his write up...

http://forums.maxima.org/showthread....ht=heater+core


Beware this is not for the squeemish!!!!!

I hope to GOD I can flush it out.