Alternator or Voltage Regulator

[cmcfaul]

89 Carrera.

Battery is not charging. Only seeing 12.6 volts at 3k RPM's. Is the Voltage regulator built into the Alternator or is it separate as it was on earlier 911's?

Any tricks to the trade for getting the fan off. I can get the nut off but know the fan is going to be stubborn.

Thanks,

Chris

[Dpmulvan]

Built in, use blocks of wood to remove fan.

[darrin]

also suggest you take your alternator/vr to an old school alternator shop and have it checked and rebuilt rather than buying a remanufactured one.

[cmcfaul]

Too late.

Just ordered a remanufactured Bosh unit from Advanced Auto. Two year warranty and only $200.

My car is mad at me apparently. Fifth thing to go wrong in a month needs some TLC.

Chris

[mysocal911]

Remember, if the alt light isn't on with the key in the run position (before starting), the alt will not begin charging.

[cmcfaul]

Thanks Dave,

The light is on before starting. It stays on at idle but goes off as RPM's increase. Thought it was a bad battery (wanted to replace anyway with a smaller, lighter one). Did not solve the problem. Getting under 13 V at any RPM. Has to be the Alternator.

Chris

[mysocal911]

Originally Posted by cmcfaul

Thanks Dave,

The light is on before starting. It stays on at idle but goes off as RPM's increase. Thought it was a bad battery (wanted to replace anyway with a smaller, lighter one). Did not solve the problem. Getting under 13 V at any RPM. Has to be the Alternator.

Chris

Then you may have a voltage drop from rear to front, e.g. at alt connection, at its connection at the starter, or at the battery.

[cmcfaul]

Well not at the battery as I replaced the battery. Starter spins happily so dont think thats it. New Alt arrives Sat. Will replace and if problem persists will check starter connections.

Chris

[mysocal911]

Originally Posted by cmcfaul

Well not at the battery as I replaced the battery. Starter spins happily so dont think thats it. New Alt arrives Sat. Will replace and if problem persists will check starter connections.

Chris

The key test is to use a clamp-on amp-meter and measure the alt current coming to battery with all accessories on.
If the alt current gets to over 60-70 amps and the battery voltage drops, then you have a connection problem from the alt.

[GH85Carrera]

Originally Posted by mysocal911

Remember, if the alt light isn't on with the key in the run position (before starting), the alt will not begin charging.

Originally Posted by darrin

also suggest you take your alternator/vr to an old school alternator shop and have it checked and rebuilt rather than buying a remanufactured one.

Originally Posted by cmcfaul

Too late.

Just ordered a remanufactured Bosh unit from Advanced Auto. Two year warranty and only $200.

My car is mad at me apparently. Fifth thing to go wrong in a month needs some TLC.

Chris

Take the old one to a local rebuild shop. Get it fixed. Likely the "new" one will not last long, and you will have a good alternator to put back in. The old one will likely last another 30 years and all the wires will be in the right places.

Example: My daily driver El Camino alternator first failure was a quick Autozone replacement. The good news is I can change that alternator in 15 minutes. The bad news is it lasted a few months. I had Autozone replace it for free, about every 9 to 12 months. I finally bought a core from a friends stash and had a local rebuilder replace the bearings with quality bearings and good parts for the rest. It last for many years, and put out more voltage. I have the old AutoZone alternator on a shelf. When the rebuilt one starts to have problems, I put the Autozone one on and have the good one rebuilt again. Now after 370,000 miles overall, I can say the local rebuiler does a far better job than some factory in Brazil or Guatemala does for Autozone. Autozone hats me for the many alternators I have gotten for free in the 29 years I drive my El Camino, and the rebuild is on there mostly.

[cmcfaul]

Replaced Alternator. All is as it should be.



$200 from Advanced Auto. Hard to beat.

[30westrob]

I have had similar experiences to Glen above. The guaranteed rebuilt replacements just do not last, yet a good repair on an OEM result in reliability. Does not make sense.
Good luck with your alternator. Rob

[mysocal911]

Originally Posted by cmcfaul

Replaced Alternator. All is as it should be.

So what is the battery voltage at idle and at 2K RPM?

[cmcfaul]

14.4 v at idle. Light is off. All is good.

It's also a Bosch. Not Volaro. Just looks better quality. Looks brand new

[911TerryT]

Reviving this thread as I have a charging issue on a 78 930. While motor was out during a restoration I replaced the alternator with a rebuilt Bosch from my local alternator guru. The original was shot and he didnt want to rebuild. I have about 300 miles on the rebuild and developed a tach jump with a engine pop. Replaced the Voltage Regulator with one from the local guy(aftermarket) and I don't have the tach jump and engine pop but I have inconsistent charging. I replaced that VR with one I ordered from Porsche(they kind of looked the same but they are not). Now I have a alt light that on at 1k and is half on at 2K rev and off at 2500K revs. Problem is my voltage isn't showing any charging at the battery,,,it sits at about 12v and doesnt budge while the light goes out at higher rev. I checked all my connections and went over some bumps and the light didnt change or anything. I was careful to clean all connections when engine was reassembled. Seems like I have less intermittent charging the warmer the motor is. I have a Odyssey battery that is kept on a tender and never had any issues with cranking power. I really don't want to take out alternator as its a PIA. If the alternator is the problem, what do I replace it with? A alternator from Porsche is about 3 weeks and 1K+ from Germany.
Any help is appreciated...

[911obgyn]

Check the wire to the starter old ,crusty, brittle they become resistors.

[911TerryT]

Originally Posted by 911obgyn

Check the wire to the starter old ,crusty, brittle they become resistors.

Thank you for the suggestion. Checked the starter wires. Cleaned and inspected. Switched out Odyssey to original battery...still have issues. I noticed that when I am getting a charge to the battery, my tach is bouncing. I just cant imagine a rebuilt Bosch would crap out this quickly but its starting to look that way. If the alternator, what next? Rebuild the rebuilt Bosch? Ugh

[cmcfaul]

Its prob under warranty. Get another one.

Got mine at advanced auto.....$200, Bosch .

Chris
89 Carrera

[911TerryT]

Originally Posted by cmcfaul

Its prob under warranty. Get another one.

Got mine at advanced auto.....$200, Bosch .

Chris
89 Carrera

Chris,
I question the quality of the Bosh rebuild. I thought I was doing the best thing by getting a Bosch rebuild but all my symptoms are pointing to a bad alternator after 300 miles. I don't think I am alone with a bad rebuild either. I hope you have better results than me...thanks

[cmcfaul]

Mine looked brand new and have had no issues yet.

Chris