My 2001 a6 2.7l twin turbo is overheating even try to run heater but now blows cold air only. What could it be, thermostat, or clogged radiator, or water pump? Please let me know what you think!!!

If your 1998 Cutlass is overheating and the heater is blowing out cold air, and you are also noticing that coolant is leaking out, there are a few possible causes. Here are some things to check:

Check for a coolant leak: Start by checking the engine and radiator for any visible signs of a coolant leak. It's possible that a hose or other part of the cooling system may be damaged or loose, causing coolant to leak out.

Check the radiator: If the radiator is not working properly, it can cause the engine to overheat. Check to make sure the radiator is not clogged or damaged.

Check the water pump: The water pump circulates the coolant through the engine. If it's not working properly, coolant may not be flowing through the system correctly, causing the engine to overheat.

Check the cooling fan: The cooling fan helps to keep the engine cool by pulling air through the radiator. If it's not working properly, the engine may overheat.

Check the thermostat: Even though you recently replaced the thermostat, it's possible that it's not working correctly. A faulty thermostat can cause the engine to overheat.

It's important to address any issues with the cooling system as soon as possible, as overheating can cause serious damage to the engine. If you are not comfortable diagnosing and repairing the issue yourself, it's recommended to take your car to a qualified mechanic.

Check for proper fluid level, water pump drive belt may be defective or need adjustment, faulty thermostat, radiator cap defective, radiator or core blocked or clogged, dirty grille. Hope that Helps

Bad thermostat or clogged radiator. coolant level topped off? overheating?

You have air trapped in system , change thermostat , bleed air from system , let it run hot while adding coolant with blower full blast on all front and rear heaters .

Bad thermostat

How to diagnose an overheating 3.7
It might be the timing belt!

The heater core is probably clogged, or the valve that lets radiator fluid flow through the core is not working.

I posted this in a different web sight I hope it helps.


Re: Overheating and blowing cold air
I have been a mechanic for 20 years. Your problem is the heater core is plugged. The cold water from the radiator blows directly at the thermostat keeping it closed even when you are overheating! BAD DESIGN!! If you look at the water flow charts in AllData you will understand. If you rev the motor to 3,000 rpm's the turbulent HOT water at the water pump impeller (near the thermostat) will reach the thermostat to open it and the car's temp will fall very fast to the correct temperature. If you remove the thermostat it will not overheat but will run way to cold. If you bypass (loop) the heater core it will not over heat.

The hot water that leaves the heater core returns to the engine at the thermostat. It is the only hot water introduced to the thermostat to keep it open and allow the water to flow from and to the radiator. I normally just back wash the heater core and get large chunks of rust flake out then its fixed. Back wash then froward wash repeatedly many times. Also flush out the motor so you don't re plug the heater core. I hope you have now blown the head gaskets or cracked a head yet. Make sure to run the proper coolant in the car so you don't promote more rust flakes. And bleed the air out as mentioned in detail by other posters.

Nobody knows this little secret. Not even Subaru mechanics at the dealer, no TSB (Technical Service Bulletins a special note after the fact to mechanics). After days and days of trouble shooting a 1993 Subaru Impreza (2.0?) I looked at the water flow chart and then it was clear what was happening. This phantom overheating problem stumps the best mechanics and sends many Subarus to the crusher.

http://www.subaruoutback.org/forums/...threadid=17264

1st you need to make sure no air in your system open you radaiator cap and your heater to max and see if air bubles or circulation is going on fill up accordingly otherwise you have blockage in your system or water pump if no circulation ////make sure no bubles all bubles should be gone////look for coolant circulation in your radiator make sure your thermostat is not defective or placed in the right position.

Check your antifreeze. Then thermostat. If the engine is up to operating temp. (hopefully not overheating) and your getting no heat then you're most likely not getting the coolant to circulate. Either thermostat not opening, heater core bad, clogged radiator or coolant system.