alternator

[laurie ledbetter]

I have vw passat wagon TDI, battery light first flickered on and off. Next day stayed solid and died while driving. Tried to jump but would not hold charge and if turned off after jump would not hold charge. Charged with another car for 15 minutes and it barely drove 2 miles. Decided to change voltage regulator aas it was easy for this car. And when removed you could see pistins low. Charged up batter over night and now drives all day , turning it off and on and will last about 1 day and half. But if I don’t charge it overnight it will not last all day. Battery test below 12.4 I think 12.14. Since I fixed the voltage regulator it definately has changed quite a bit, holds a charge for more than a day. I am out of town and the mechanic I met with wants to change the alternator but I cant help to think something else is wrong since I saw such a change for the better after changing the voltage regulator and seems this part is most of what is rebuilt with a alternator. HElP

Topic

[Ingvar]

Buy this:

http://www.harborfreight.com/battery-terminal-cleaner-94450.html

And clean terminals.

After done, tighten up alternator belt.

Please.

[Erin]

The mechanic that wants to swap the alternator, has he tested it?

Of course do what Ukrkoz said just to do the “simple solution” if that is all it would take.
Do not overtighten the belt though and if I had to bet, I would say it probably is ran by a belt with an auto-tensioner.

If the alternator IS bad, well sadly it is not unlike alternators to fail, especially the ones that are a REAL PITA to get to. Like the ones on the bottom back of the engine, where road water can splash on them easily… :angry:

If the voltage regulator was bad, it is likely the alternator was already on it’s way out since those pieces work together.

[Bill]

It’s possible that the regulator failed and damaged the alternator. You really need the whole system tested to find the bad component(s) Most parts stores in the USA will do that for free.

[laurie ledbetter]

Good advice, I will check all the connections again. I had heard so many say I could just change the voltage regulartors and save on the alternator. I guess I will try changing the alternator. Are you saying wysetech that if I take it off and take it to a auto parts store they can tell me what part is bad , or take it while its still on the car? thats good toknow

[619DioFan]

If you can take the car to a parts store they will test the charging system on the car. if you have a dvom you can test the alt output with car running by setting the meter to volt test and touching the leads to the batt terminals at the batt ( red to pos black to neg ) make sure to have the batt load tested ( parts store can do this as well ) a bad batt will not hold a charge.

[Lorrin Barth]

The parts house isn’t going to tell you what part is bad (they won’t know) but they should have a alternator tester. If the voltage regulator is part of the alternator I’d pull the alternator and carry it in if that is an easy job.

BTW, what is the voltage across the battery after you’ve taken it for a drive and when the engine is idling in your driveway.

[george gonzalez]

It’s probably the alternator. You can check this by turning the headlights on for a few minutes until the lights start getting yellowish a little bit. Now start the engine and the lights should get back up to normal white light. If they don’t get any brighter then the alternator or the regulator are bad. If you’ve changed the regulator, then that’s not it.

[Lorrin Barth]

Another thing to have tested at the parts store is the battery.

[Ingvar]

On a philosophical note, I have been in auto repair forums for years and many of them.
What I found is that folks somehow are always inclined towards a more expensive and, likely, unnecessary repair, but will shy away from very basic, simple, but known to work solutions. Like cleaning terminals, tightening belts, checking on tensioner, or Seafoaming fuel lines or engines.

[Author]

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