So I just bought a 2000 A6 Quattro 2.7t auto with about 194,000 miles for $680. The guy told me the only thing he knew of was the power steering mounting bracket was broken. He gave me the bracket and the serpentine belt and after a couple hours I managed to replace it. Car started right up and drove.I soon realized the car was over heating but neither of the temp gauges read anything. I have ordered a coolant temp sensor, a thermostat, a water pump and a timing belt. Any advice while I'm waiting for the parts to arrive?

 

Make sure all the air is out of the coolant system. It has to be bled as water pumps won't pump air, and temp sensors have to be in direct contact with the water in order to read the temp accurately.

 

Thanks Dave. The last owner put regular coolant in it so I do intend to flush it and replace with g-12. The oil temperature gauge doesn't read anything either.

 

My A8 started doing goofy stuff back in the fall on starting up. The temp gauge on mine was not reading either. I connected my OBD scanner and it gave a "Coolant Temp Low" error code. I drove it, watching the coolant temp sensor information on the screen. One minute it was reading about 180 some degrees.. I happened to look down a few minutes later and noticed it said 70 some degrees for a few seconds and then went back to 180.. The temp gauge on the dash was dead.. I picked up a temp sensor on the way home from work that day. After swapping it out, the gauge worked properly and the weird starting and running issues went away. Swap that out temp sensor first before switching to G-12 just to make sure. Be careful with the plastic clip when you remove it to swap out the sensor. I broke mine biggernshit removing it and didn't have a spare.. LOL Actually, I'd remove the clip and pull the sensor out with the electrical connector still on it if it's hard to get it disconnected while mounted. Mine did NOT want to unsnap and it was down in there where I couldn't get my fingers in there and grab it. Plus I wasn't exactly sure on how to make it release. Once I removed the sensor, I was able to disconnect it without potentially damaging the connector itself (NOT good)... Make note when you remove the sensor whether there is water all the way to the top of opening. This will tell you that the sensor is actually contacting the coolant and there's at least no air there. The temp sensor on my A8 is at a point where if you remove it, coolant will not run out uncontrolled as if it were way below the top of the water level when full (about the same level as the bleeders on the heater hoses). I'm not sure about 2.7s but I would think it would be similar in set up.

Another question. Are the radiator fans coming on when it's warm? They run off a different temp sensor in the radiator.

 

I'm not sure if the fans were working. I feel like they weren't. I can't do much now, I have the front end tore down in anticipation for the parts. At this point I figure even if they are not the issue it won't hurt to a few new parts on it. I'll let you know what happens in s fee days. Thanks again.

 

I'd go ahead and put in a new fan temp switch while I had it apart. It mounts into the radiator directly. It's a $20-30 part and that much more insurance to help prevent another overheat.

 

I received the temp sensor, replaced it and nothing happened. All of the fans do engage. At this point I'm wondering if it is in fact over heating. I understand they run hotter than normal cars. Around 225.I guess that is neither here not there because I have no way to check the temp. The check engine light is on but I'm afraid to drive it anywhere to have it diagnosed. I don't want to blow it up. Sorry for rambling, I am just at a loss.

 

You really need to get the OBD codes from the ECU. You can get a small OBD reader for $20-$30.

 

I just borrowed one from a friend and ran it last night. It pulled p1122, p1118, p0140