Alpine951

I noticed driving around today that the voltage meter on my car was under 12 on the gaguge. After work driving home with the lights on, heater fan on, and rear defroster on its dropped to 10 by the time i got home. What should i check besides the belt?

Cyrus951

Check to make sure the gauge is accurate by hooking a multimeter to the battery before going to the extreme..

RMills944

If the belt isn't loose, and the voltage keeps dropping, then it's the alternator (probably not the btter if it's happening while your driving). I'd stay close to home until you're sure the voltage doesn't come back up when everything is off.

Autozone and places of the like can do a test for you - I'm not sure how accurate it is though.

Alpine951

What exactly does the stock gauge measure? Voltage at the battery?

IceShark

No, its voltage coming out of the fuse relay board so it can be different than what you have at the battery due to voltage losses through the stock wiring especially under heavy load like you had on your way home.

Still, something is wrong and my guess would be the alternator since you were able to watch the voltage fall substantially in a short period of time. Do you have the original voltage regulator? Could be worn out brushes. You really need to pull the alternator and check/test it out. Unfortunately, you have a turbo and pulling the alternator is no 5 minute task. You have a lot of stuff to remove from the top and bottom to get to it and pull it out.

Oh, and BTW, if your system voltage falls too far below 10 volts your DME/ECU will stop working. No spark, no fuel, no go.

Alpine951

Ice,

I bought the car 4 years ago. At the moment its only got about 60k miles on it. Probably original regulator. Is the regulator inside or part of the alternator or is it a separate component on my car.

Alpine951

About two weeks ago the coolant hose that comes out the bottom of the expansion tank for the turbo coolant pump that runs during shut down burst. Its in the genral area above the alternator. Think this could have caused it?

Kevin Baker

Very possible. You should be able to take the car to one of the major auto parts houses, and ask them to test the altenator. They should be able to test it while its in the car. When my altenator went for the 2nd time, it had the exact same symptoms that you are describing.

Cyrus951

If you want your alternator tested while it's still in the car, all Kragen does is hook up a multimeter and check for 13-14 volts when the car is running.

But, they can test the alternator alone for free too, you'll have to pull it out (lots of work).

A dead Bosch alternator at 60k miles tells me something caused it to go bad (water, etc)

dme

There is a brush regulator assembly on the alternator. It is a breeze to replace with the alternator out of the car. I bought the part from Ice for around $20. You may not be able to get the alternator out in 5 minutes but it can be done easily on a Saturday. The only part I hate is draining the coolant. Some people only drain part of it.

Alpine951

How can an auto parts store test it still in the car when they can't get to it?

IceShark

Alpine, The regulator is on the back of the alternator held down by two screws. The attached regulator brushes stick inside the case. Pretty easy to change out, a minute or two, once you have the alternator on the bench.

At 60,000 miles it is unlikely the alternator guts are bad unless you have been loading it up with huge draws like a big amplifier. Or overheating it due to lack of the heat shield cone and vent duct. The rule of thumb is don't go over 80% of rated capacity for over 20% of the time. You will kill an alternator quick. But the regulator and brushes could fail in this time frame fairly easy. And replacing that is cheap - I sell them for $21 with the shipping in the lower 48 USA.

The burst hose may have done something from shorting to causing the brushes to wear faster, I guess. You would have to test and then open up the case to see what is going on. In any event, I doubt the leak destroyed the entire alternator and you have to buy a rebuilt. You can probably solve it with a new voltage regulator, maybe a diode pack (they are around $50), and some cleaning if you have a bunch of coolant dried and crusted inside the case.

As far as testing, pulling the alternator and taking into the shop is the easiest way for the shop. But some places have test equipment with an inductive pickup and they can narrow down the problem. That you won't get done for free but all the chains will test the alternator out of the car for free, usually. Though I wouldn't trust them as either a moron is doing the test or a smarter guy that is trying to sell you a rebuilt alternator after they declare it dead.

Cyrus951

They check the voltage at the battery.

Alpine951

I have an old analog meter that i just went to the car with after cleaning all the snow off that we got hit with yesterday. With the car not running the meter says 12.5 volt at the battery. I jumped in and started it up and the stock gauge was now reading between 12 and 14. i turned the rear defroster the radio and the headlights and it only budged slightly less. maybe the belt was slipping?