vjd3

Drove the 993 last Friday, parked it in the garage ... Sunday afternoon, wouldn't start. Plugged the Porsche trickle charger in for a while yesterday, light was not staying on to indicate it was doing anything for more than a couple of minutes. Car still won't start ... insert key, get the warning tone but it's wavering in pitch all over the place and nothing's happening.

Figured the battery might be bad, pulled it, ran it over to the Autozone, it showed an 85 percent charge, should have been enough to turn it over.

Any ideas? Both cables were tight on the battery, had a bear of a time even getting them off of the terminals. Battery's only three years old and tested good on Autozone's tester.

Stealth 993

Is it even turning over? If the tone is changing as you try to start it, that tells me it's drawing a lot from the battery. Have you put a voltage meter on the battery?

Maybe you have a stuck starting solenoid. You may have to get under the car & hit the starter with a mallet.

vjd3

Well, quick update ... I put the battery back in (had Autozone charge it to 100 percent), car started right up.

Maybe the alternator is going and the charge had dropped just enough not to start it? I had an issue a couple months ago where the radio was blinking off when the high beams were flicked on, sent the car to the shop and they said the charging system checked out fine.

Mike Pezely

Have you cleaned the posts on the battery and double checked the connection on the ground cable?

Stealth 993

All you need to do is check voltage with the car off, & with it running.
Around 12.5 when off
around 14.4 when running, you may have to have a fast idle to get it up.

Benton

Yep, I would bet there was some corrosion on the posts (hence the difficulty in removing the cables). I had the same problem a few years ago. Even if you don't see obvious corrosion, it can cause major issues.

Also check to make sure all of the rubber plugs are in place under the spare tire.

vjd3

Thanks for the help. I put a meter on it ... reads 12.8 not running, 14.0 at idle (and revving), 13.8 with the AC on. A little weak, maybe?

chris walrod

I would think it was just a bit of a bad connection at the posts.

black ice

3 years from a battery is not unreasonable.

dave

vjd3

Interesting ... I ordered one of those cigarette lighter voltmeters so I can kind of keep an eye on it.

I was ready to buy an Optima 35 but the battery tested good. Ironically, the battery on the 99 740iL failed as well. Both cars were dead as doornails on Sunday afternoon. (BMW got a new battery yesterday.)

Can I just use a wire brush to clean the posts? Baking soda?

What is the significance of the rubber plugs under the spare tire? Protect the drain holes from corrosion? I think there is one missing under there. Was glad to see no battery acid residue under the lid.

nile13

Vic, i believe the plugs simply prevent water from coming in from below as you splash through puddles.

As far as leaning the posts, yep, regular wire brush will do. Also clean the connectors on the wires hat go on top of posts. Be careful not to get dried up acid on your hands. Not particularly harmful, but unpleasant, especially if yo have cuts or lick your fingers.

Deadeye

Mike, are you an insomniac or just an early riser?

Slow Guy

Yes, baking soda mixed with water works well, just make sure you remove the cables from the battery as you don't want the solution inside the battery cells. Disassemble the battery post clamps as much as possible before putting them in the solution. leave it in for a min. or 2, rinse and wire brush clean. Also wire brush the terminal posts too. Assemble back together making sure the clamp is as close to flush with the top of the battery post as possible. This is critical as you want as much contact area on the battery as possible.

Always remove the Neg terminal first and when reinstalling always reinstall the Pos term first. Also check to make sure the car end of the Neg cable is snug too, should go to the frame of the car (1/2).

Battery voltage sounds ok but that doesn't mean the load test would be good but from what you described it sounds like a bad battery terminal connection.

Also, when you speak of "car won't start" the biggest item you need to include is whether the engine is "turning over" (cranking) or not. It makes a big difference on where you start troubleshooting.

techman1

When checking voltage at battery, and it checks good, keep this in mind:

This may not be what the car is seeing. Try clipping your tester on the end of the negative cable when doing the tests, and see if there is a difference. I have been told the negative cable can build up resistance over time.

I would guess this would apply to the positive cable, but a lot harder to test.

A new negative cable fixed my problems. Not sure if it was all the cables fault, maybe a combination of the connection to the body and the cable.

nile13

Are you kidding, Dennis? Who in their right mind would wake up this early?

You now know why I'm grumpy at 8AM on autocross weekend I do mellow out towards afternoon when I actually wake up and start driving. I'm just wondering sometimes what instructions my students get in the morning sessions when I'm still blissfully asleep in their passenger seat. They think they get better in the afternoon runs because of morning instructions. Ha!