2001 Silverado 4.3L V6 coolant/heater issue

[shorty2313]

I am new to the boards. I have a 2001 Silverado 4.3L V6. I am having an issue that just started last night and I can not figure out what it would be. Hoping Im over thinking it and its something simple. Here is my situation:

 

My heater has not been working for almost all winter (maybe longer but I obvisiously didnt run it spring, summer or fall). It worked just fine last winter. I changed out my water pump last summer. I changed out my thermostat about a month or so ago. Heater would blow slight warm air on 1 or 2 on the blower settings. 3, 4 or 5 would result in cold air. Last night we started smelling antifreeze and the smell gradually started getting stronger. I checked to see if there was anitfreeze in the coolant tank adn it was a little low. I then did the "grab test" on the radiator hosses to make sure that both hoses were hot. Only the hose coming from the top of the radiator was hot. The one coming off the coolant tank and connecting to the bottom hose from the radiator was cold, the hose coming from the bottom of the radiator and it was cold as well. The temperature gauge never went above 210. I drover with heater on adn with it off. And the temperature never went up or down regardless. But the smell lingered. I tried turning on the defroster and the air would blow but it was cold air. My windshield now almost instantly fogs up regardless if it is on or off. The antifreeze that I put in yesterday is still in the tank. It has not spilled out. There is a small spot where the over floww drain hose is but is very very small. Almost like it was just a few drops.

 

I am completely lost on what to check or look for. Any and all help is greatly appreciated. Thank you.

[Doug_Scott]

The smell is likely coming from the heater core inside the heater box. Check the bottom of the heater box and see if it is wet, also check the carpet under the dash as well. If you find the box is wet, tough the fluid, and taste it. Antifreeze is sweet tasting(and the amount you are tasting will not hurt you). Your windows fogging up make it sound like the heater core is leaking as well.

 

As for the hoses in the reservoir being cold, that may be normal. I do not know the cooling system setup in your truck, so cannot really guess as to what those hoses should be temperature wise. If your truck has the traditional setup, then the reservoir is not part of the cooling system's normal operation. There would be no flow of antifreeze through the bottle until the rad pressure exceeds about 15psi. The newer trucks changed that setup. The reservoir is part of the pressurized cooling system now. I have not looked at mine in any detail, and do not know if the reservoir is used in the normal flow and operation of the cooling system. It still may not have coolant flowing through the reservoir as a normal part of cooling system. If your reservoir has a rad cap like you would see on most radiators, then that tank is part of the operating cooling system. If I remember, I will check my reservoir tomorrow sometime and post back here, unless someone else knows the proper operation and posts here.

[shorty2313]

Thanks for the info Doug. That helps alot.

 

I edited my 1st post, I grabbed the hose coming off the top of the radiator (it was hot), the hose off the coolant tank (it was cold) and the hose coming off the bottom of the radiator (it was cold).

[Jsdirt]

Yep - my bets are on heater core. To add insult to injury, that's a real fun job to do too ...