Hi guys, first thanks a bunch. Our 2000 A6 2.7t tip with 134k had been running really well. Today I suddonly noticed there's no heat from heater, only plenty of ice-cold air. Then I noticed the coolant temperature was 2/3 on the gauge, compared to 1/2 on a regular day. Very soon, the overheat alarm came on. We had to pull over to the shoulder, call AAA and cancel the trip.

Oh, 2 more things. The hose between the radiator and coolant tank was warm, if not hot. There's no apparent leak.

So what do you think most likely is the problem? A seized water pump? If that's the case, I bet I am looking into some serious money...It's too cold and probably I am too busy to do those myself, I bet. The timing belt was replaced 50k ago with a new water pump.

 

I say its the thermostat!

 

Thanks. I certainly understand that a stuck T-stat would cause overheat. But one thing I don't understand. I thought the heat is NOT regulated by T-stat. Or in other words, no matter the T-stat is open or close, the car should have heat. That's why I thought it's the water pump. Do I miss anything? Thanks.

 

well i think in most cars the heater core is after the radiator. [where the thermostat will only open once it (eng/coolant temp) reaches a sertain point, allowing coolant into the radiator and THEN heater core (when heater is on). but im not sure if this aplies to audis.
let me know if you need a more in depth explanation....

 

If you are low on coolant, air gets into the system and into the heater core, thus no heat. This also causes the temp gauge to go up.

 

Couple things-

Low coolant will definitely cause this problem. However, you would have received a low coolant alarm WELL BEFORE an over heat alarm.

If the thermostat is stuck CLOSED (which is usually the position they fail in), no coolant will get to the core- On any car that I know of. Which is why your hearter suddenly starts working in the mornings. Once the thermostat opens up it sends the warm coolant to the heater core.

My money is on a $20 thermostat

 

^^yeah thats pretty much wat i was trying to say lol

 

Yep probably the thermostat... I don't know about the 2.7 but if it were a 2.8 I'd say do the timing belt etc again cause you would have most os it apart to do the thermostat.