Alternator or battery? One is going bad. Also, overheating issue.

[x4frnt]

04 B6 S4 M/T

Here is the problem: my battery or my alternator has gone bad. I went to O'Reilly's to get both tested, they tested the battery first, said it was bad, then tested the alternator and said that was also bad. So, I went to get Advanceauto to get it tested as well, they said I need a new battery and the tested the alternator as well, I started the car and was told to rev to 2k rpm to test the alternator, and it was between 13-14v, so he said my alternator was good?

the car is not my daily driver, and in the afternoons I typically take it for a brief drive. For about two weeks I've been experiencing problems with it cranking up, it will turn over once or twice and then it's dead. But after driving it for 30 minutes, it will start but just barely. I have no issues of my car cutting off while on the road or even a lack of power I the car, so it must be my battery right? Fingers crossed it is.

Second issue- i replaced the radiator due to a small crack and now my temp meter is faulty, i can drive it for 20 minutes and it won't move from the Cold, the all of a sudden it will go to normal for a few minutes then back down to cold. Every now and then it will go all the way up to the overheating stage and my coolant light will come on, but then stabilize back to normal? Anyone have any ideas why this might be?

Thanks for the feedback

[AllroadMass]

04 B6 S4 M/T

Here is the problem: my battery or my alternator has gone bad. I went to O'Reilly's to get both tested, they tested the battery first, said it was bad, then tested the alternator and said that was also bad. So, I went to get Advanceauto to get it tested as well, they said I need a new battery and the tested the alternator as well, I started the car and was told to rev to 2k rpm to test the alternator, and it was between 13-14v, so he said my alternator was good?

the car is not my daily driver, and in the afternoons I typically take it for a brief drive. For about two weeks I've been experiencing problems with it cranking up, it will turn over once or twice and then it's dead. But after driving it for 30 minutes, it will start but just barely. I have no issues of my car cutting off while on the road or even a lack of power I the car, so it must be my battery right? Fingers crossed it is.

Second issue- i replaced the radiator due to a small crack and now my temp meter is faulty, i can drive it for 20 minutes and it won't move from the Cold, the all of a sudden it will go to normal for a few minutes then back down to cold. Every now and then it will go all the way up to the overheating stage and my coolant light will come on, but then stabilize back to normal? Anyone have any ideas why this might be?

Thanks for the feedback

Sounds like either your alternator is not charging the battery while you're driving or the battery is not holding a charge.

How old is the battery? Get one of these off Amazon and you can tell if the batter, alternator, or both are bad."Schumacher BT-100 100 amp Battery Load Tester"

Sent from my Nexus 5 using Tapatalk

[x4frnt]

Battery is 5 yrs old 😳

[x4frnt]

Anyone have a recommendation for a good replacement battery?

[gautam]

I had a similar problem, I was having start-up issues (not as bad as yours) but after the car sat overnight or sat out in the heat while I was at work (I live in Texas, it's incredibly hot here) the car would hesitate but eventually start. My battery is only about 3 years old. It culminated in my positive terminal blowing up yesterday, I started a thread about it (http://www.audizine.com/forum/showth...e-in-the-cabin!!) I really hope this doesn't happen to you, I most likely have a bad starter motor that caused the issue.

The start-up problems started more than a month ago, I took it to Auto Zone and they said my battery was low on charge and that my alternator was bad, I took it to my regular shop and they said the same thing, and I paid Audi Plano $195 for a diagnosis and they said everything was good including all the engine electricals (alternator, starter motor, etc.) so my advice to you is take it to an Audi dealer and have it diagnosed. If there is something wrong they'll usually take the diagnosis fee off of the overall fee to fix the issue. In my case, they gave me a clean bill of health only for it to break down soon after, and I will be taking it up with them and Audi of America, but please look in to your starter motor, I really hope what happened to my car doesn't happen to yours!!

[gautam]

Turned out to be my battery, some bad luck and a grounding issue, I'll be posting about it soon on the thread I started. If you're a DIY person you can investigate for yourself. Give me about 30 mins and I'll post about it.

[AllroadMass]

Went to advance auto parts for my wife's 4.2 allroad. Around $190 and they can even put it in for you if you wanted.

[x4frnt]

Thanks for the advice, so I had my radiator replaced and now am running into a new issue, hoping someone can give me some insight as to the root cause of the problem. My temperature sensor is being very erratic, sometimes it doesn't move from the cold bar at all and then when it does it will jump to the middle where it should be and sometimes it will go all the way to the hot side causing my coolant light to come on. When this happens the A/C no longer blows cold air and it acts like its overheating (the smell of radiator fluid, smoke etc). Every now and then when this happens the oil pressure light will come on but then will immediately shut off. This happens off and on, like I said it's very erratic. I noticed this all while driving yesterday. I'm wondering if my water pump is the cause of this or if it's something else, any ideas?

[AllroadMass]

Did you bleed the coolant?

When I had to take my front end off, I didn't bleed the coolant as stated in the Bentley manuals but what I did was filled the coolant res and watch for air bubbles to come up - this took me almost 5 minutes. Be patient. Started the car and that should circulate the coolant. shut off the car, top off the coolant and watch for more air bubbles to come up. I cycle this procedure a few times and then my coolant level stayed constant in the tank.