Audidiehard

High mileage A6, engines runs normally for about an hour, shut it down, restart and then the batt light comes on and the charge starts to drain. Let it sit overnight and back to normal for about an hour again. The engine temp varies from 0 - 90 then back down again, but the thermostat hasn't been working for a while. Im retired and need to watch my spending so Im still doing my own work, any help out there would be more than welcome.

4Driver4

Replace your coolant temp sensor and your alternator.

Audidiehard

Thank you for the reply, Why disregard the thermostat?

4Driver4

Because I think it isn't broken. Why are you sure it is a problem?

Airbag

Thats was funny right there .. i dont care who ya are ..

OP the CTS is a KNOWN point of faliure, they fail very often, they are cheap and easy to change. It Is possible the T-stat is bad but start with the leat invasive thing . the T -Stat will ultimately be a nightmare...
End of the day if you are going to pull the front of your car off to change that T-stat , alternator, and while you are there you wil be doing timing belt and pump .. so whynot change the CTS as driver suggeste and see where you ae at

Good luck.

Audidiehard

Sorry, old school I guess, certainly didn't mean to offend. Thanks for your help, I'll get to it.

4Driver4

Nor did I.

Was seriously asking: Why do you think it's bad? Gauge is not a reliable indicator.

Audidiehard

Have it apart now, front end splayed open. Old school thinking was if the temp won't stay up when its cold out, the thermostat was punched. It was my first thought thats all. Just on my way out to buy parts.

DaveA6

Have same problem. T stat regulates at temperature if it gets there. Not ready for a t belt yet, so put a placemat in front of the radiator in winter. Slow to get to operating temp, but it gets there!

Audidiehard

You had it nailed, I replaced the alternator (wow, what a job) and the CTS. The CTS did the trick, normal temps restored. Well done sir, thank you.

While running it on a test drive I noticed that the amps start out nat 14 and slowing dwindle. I never noticed this before is it normal. Im not getting a battery light. The generator was used when I put it in.