bark4snow Posted December 30, 2009 Share Posted December 30, 2009 Help! I'm new to the forums. But I have a problem I can't find a solution to at my local dealer. My legacy sedan at 120K miles runs great during the summer. It keeps a constant temp. However, in the winter when I am up in the mountains skiing the problem arises. The car starts up and warms up normally the heater begins blowing hot air. Then when I head down to the flat lands (about a 2000 foot drop) the heater starts blowing COLD air. Most of the drive down I don't have my foot on the gas. But when the terrain levels out somewhat and I have to use the gas more, the car begins to overheat badly. Still the heater is blowing cold air! I pull over and wait for 10 minutes or so to cool the engine, then the heater starts working fine and the car keeps a normal temp. I have checked the radiator fluid and my mechanic has replaced the thermostat. Anybody have an idea what is going on? Thanks! Link to comment Share on other sites More sharing options...
amp27 Posted December 30, 2009 Share Posted December 30, 2009 你检查水泵和同步带的东西？ Link to comment Share on other sites More sharing options...
Aczwild Posted December 30, 2009 Share Posted December 30, 2009 Unfortunately those were the exact problems I had when my Headgasket went on my old '97 GT. Of course it had to happen on the coldest days of the year. JDM'd All to hell Thanks Jimmy @ Hkc-Speed.com! RIP Coxx & Thanks Link to comment Share on other sites More sharing options...
bark4snow Posted December 30, 2009 Author Share Posted December 30, 2009 Yes, I checked the belts. All are in good order. Link to comment Share on other sites More sharing options...
Stang70Fastback Posted December 31, 2009 Share Posted December 31, 2009 Headgasket dude. It's leaking and allowing combustion gasses from the engine to force their way into the coolant. These gasses fill the coolant lines and since air is an insulator, the engine overheats. Your heater takes heat from hot coolant flowing past the vents, but since it's just insulating air, you will not get any heat. First time it happened to us was in the mountains in Vermont in the winter. The engine has to work harder going uphill, so it will overheat. On flat terrain, it tends to be OK until the problem gets worse, since the airflow over the engine and stuff tends to keep it cool when it's not working hard. You'll probably notice that it will tend to overheat as soon as you pull off the highway, as now there isn't enough airflow to cool the engine. Link to comment Share on other sites More sharing options...
bark4snow Posted January 1, 2010 Author Share Posted January 1, 2010 Still the car heats up and acts normally when I am going up hill or on the flats. It only blows cold air after I head downhill for a long while. It does seem to act like an air bubble though. Perhaps going downhill moves an air bubble that prevents heat exchange. The car is topped up with coolant though. Link to comment Share on other sites More sharing options...
jospgut Posted January 1, 2010 Share Posted January 1, 2010 head gaskets! Link to comment Share on other sites More sharing options...
Stang70Fastback Posted January 1, 2010 Share Posted January 1, 2010 Hmmm, you say the coolant level is fine. On our car, the air being forced into the lines meant coolant was forced out of the overflow container. Perhaps your issue is as simple as the water pump failing? Link to comment Share on other sites More sharing options...
one bad bg Posted January 4, 2010 Share Posted January 4, 2010 if its not the headgaskets, you might want to look into a high temp thermostat. not too high though, dont go over 190* in the winter you could prolly get away with 200 or 210 but i wouldnt push that in the summer months Link to comment Share on other sites More sharing options...
ehsnils Posted January 5, 2010 Share Posted January 5, 2010 Yet another factor - what temperature is your anti-freeze at? You may just suffer from an ice plug in the lower radiator hose! Link to comment Share on other sites More sharing options...
skibob6 Posted January 5, 2010 Share Posted January 5, 2010 However, in the winter when I am up in the mountains skiing the problem arises. The car starts up and warms up normally the heater begins blowing hot air. Then when I head down to the flat lands (about a 2000 foot drop) the heater starts blowing COLD air. Most of the drive down I don't have my foot on the gas. But when the terrain levels out somewhat and I have to use the gas more, the car begins to overheat badly. Still the heater is blowing cold air! I pull over and wait for 10 minutes or so to cool the engine, then the heater starts working fine and the car keeps a normal temp. IDK if this is relevant but, when you start your car it checks your MAP sensor and uses it to check altitude and compensate for air density and what-not. the critical part is that it only does this during startup, so if you travel from a high altitude to a lower one or versa-visa it is running a fuel control strategy based on an incorrect air density. This could have an effect on your over-heating or it could not. if you pull your car over and shut it off, when you start it back up it will resample the altitude. Hopefully that helps you in some way. As for your heater problem you may look to see if your blend door is functioning or maybe check your heater core for restrictions? Link to comment Share on other sites More sharing options...
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