"nmischu" wrote: > I drive a '96 Blazer. Recently the engine temp indicator has > been reaching the red lines provoking the check engine light. > Upon inspection of the coolant level and search for leaks, i > came up with nothing. When I turn the heat up to full blast > and double the idle the problem seems to go away, but with > that an odd smell comes from the vents. The problem will go > away for a day or two and resurface upon the first drive of > the day. I'm hesitant to take it in because i've been screwed > before. I would like to know if there is anything I should be > looking for or anything i can do myself in order to avoid a > trip to the shop, or at least know something about the problem > before i commit to repair. Thank you very much.
You say you have an odd smell from the vents after using the heater, have you checked the carpets under the dash to see if they are damp indicating a leaking heater core? If the heater core is leaking and the coolant is in the carpets you should be able to smell it all the time. When you checked for a leak in the cooling system was the coolant level lower than normal? If it was then it is going some where. The comment on the odd smell made me think of this. There are several possible causes to overheating. Some have been touched on by others, like the a lack of air flow thru the radiator. Some others are a bad thermometer which will not let the coolant flow. A bad waterpump will not move coolant thru the system. If you have had the system worked on lately, you may find the problem is Air in the cooling system. It can be a pain to remove air from some systems but it is a must to get the air out. If the fan is not working, then the radiator will not cool the system enough at slow speeds. At highway speeds there is enough air moving thru the radiator to keep the system cool unless the fins are plugged full of mud, dirt and bugs as mentioned by others. Also the smell from the vents may be unrelated, such as a mouse or other critter built a nest in the truck. Or something was spilled into the vents making the smell.