Wierd Alternator issue....thoughts?

[Doogie]

So today I decided to take #3589 to my monthly Austin Healey meeting about 10 miles away. I had just sold my '59 AH "Bugeye" Sprite to a gentleman who was visting Ken's shop and I told him I would introduce him to my "other" club. Not having the Bugeye, I decided to take my other "British" car.

I had it out just yesterday cruising around, even stopped and put 5 gallons of gas in it. (Ok, also stopped to get beer ) Car ran great, no issues.

So, I pulled the car out of the garage, and went on my way. Normally, I wait a few minutes at least before going anywhere to let the car settle in. I have about 60-90 seconds of minor idle hunt as the car warms up, then it goes completely away (O2 Sensor warming up). This time I just jumped in and went.

The car ran rough as I pulled out of the driveway and onto the street. I chalked it up to the O2 not being in the game yet, and ignored it. But after about a 1/4 mile, I happened to look at the gauges (I drive with 1 eye on the gauges!) and noticed the Volt meter was hovering at 10 volts! Eeek! Uh-Oh! But wait, the Battery light is not on?

OK, turned around and headed home. Pulled in the driveway, but decided I wanted to look at the alternator and belt while it was running to see if anything was weird. I stopped in front of the garage, engine on, and went back to check the engine. Lifted the Louvers, engine cover, everything spinning nicely but still kinda running craply.. Huh. Twisted the throttle spool and revved it up a couple times, watching the belt. everything seemed fine, and, she is running noticeably better! huh. Ok, hopped back in to pull the car into the garage and noticed the Volt meter now sitting above 13 volts. Wha???? turned on the lights, A/C, whatever, voltmeter stayed where it should. Huh. OK, lets go to the Healey meeting. No guts, no being stranded on the side of the road!

Drive to the meeting at a club members house and parked in his driveway, no issues. A few minutes later, other member appear and I need to pull up. Got into the D, started it up, and volts are at 10 again! Wha?? Revved it up a few times and volts jump to 13! Yeah! Huh.

After meeting (dark now) I hop in the car expecting to have to Rev it up to get the alternator to start working, but not this time. Start her up, volts at 13 right off the bat. Drive home with headlights on, volts stay above 13 the whole 10 mile drive home.

Thoughts?

Weak alternator?
Weak battery?
loose connector?
"Don't worry about it mine does the same thing has for years and I'm the original owner"?

Doogie

[Chris Burns]

Sounds like the alternator is going bad to me.

[Jonathan]

Did you wash the car earlier or perhaps have the engine bay get wet somehow?

[DeLorean03]

See ya tomorrow at Ken's ....

Original alternator?

My guess, that one lil brown wire that connects to the voltage regulator on the alternator body. Never hurt to change fuse #5 to be safe.

So today I decided to take #3589 to my monthly Austin Healey meeting about 10 miles away. I had just sold my '59 AH "Bugeye" Sprite to a gentleman who was visting Ken's shop and I told him I would introduce him to my "other" club. Not having the Bugeye, I decided to take my other "British" car.

I had it out just yesterday cruising around, even stopped and put 5 gallons of gas in it. (Ok, also stopped to get beer ) Car ran great, no issues.

So, I pulled the car out of the garage, and went on my way. Normally, I wait a few minutes at least before going anywhere to let the car settle in. I have about 60-90 seconds of minor idle hunt as the car warms up, then it goes completely away (O2 Sensor warming up). This time I just jumped in and went.

The car ran rough as I pulled out of the driveway and onto the street. I chalked it up to the O2 not being in the game yet, and ignored it. But after about a 1/4 mile, I happened to look at the gauges (I drive with 1 eye on the gauges!) and noticed the Volt meter was hovering at 10 volts! Eeek! Uh-Oh! But wait, the Battery light is not on?

OK, turned around and headed home. Pulled in the driveway, but decided I wanted to look at the alternator and belt while it was running to see if anything was weird. I stopped in front of the garage, engine on, and went back to check the engine. Lifted the Louvers, engine cover, everything spinning nicely but still kinda running craply.. Huh. Twisted the throttle spool and revved it up a couple times, watching the belt. everything seemed fine, and, she is running noticeably better! huh. Ok, hopped back in to pull the car into the garage and noticed the Volt meter now sitting above 13 volts. Wha???? turned on the lights, A/C, whatever, voltmeter stayed where it should. Huh. OK, lets go to the Healey meeting. No guts, no being stranded on the side of the road!

Drive to the meeting at a club members house and parked in his driveway, no issues. A few minutes later, other member appear and I need to pull up. Got into the D, started it up, and volts are at 10 again! Wha?? Revved it up a few times and volts jump to 13! Yeah! Huh.

After meeting (dark now) I hop in the car expecting to have to Rev it up to get the alternator to start working, but not this time. Start her up, volts at 13 right off the bat. Drive home with headlights on, volts stay above 13 the whole 10 mile drive home.

Thoughts?

Weak alternator?
Weak battery?
loose connector?
"Don't worry about it mine does the same thing has for years and I'm the original owner"?

Doogie

[Nicholas R]

Which alternator do you have? Was it raining at all while you were driving?

I dont think your alternator is half working then fully working; I think it's pretty clear that it is not charging at all, then suddenly fully engaged.

Doesn't sound to me like the alternator is going bad, it just sounds like you've got some bad continuity somewhere. If you're still getting 13v when everything is engaged, then it's unlikely that the bulk of the alternator is bad.

I'm trying to remember how the bulb in the dash works. (I'm spitballin' here so if I'm wrong someone please correct me) The light in the dash is not powered by the alternator, it actually grounds through the alternator (or rather the voltage regulator in the alternator). The light is on the common power circuit for all of (or at least most of) the lights in the dash. The 12 volts running through that light act as a signal to trigger the voltage regulator in the alternator to begin charging. The amount of current required to trigger the voltage regulator is low enough that it does not light the battery light, but high enough that if you use an LED the resistance of the circuit is too low, the led will light, and the signal will still not be strong enough to trigger the voltage regulator. I don't know the exact circuitry in the alternator, but I know that the dash light only lights if you have low alternator output, or no output but still good continuity. If you have NO continuity between the dash and the alternator (If the alternator plug is disconnected for example), you will have no alternator output and the dash light will not (because in order for the light to come on, it still has to be grounded and if the alternator is unplugged, there is now way to ground the light).

Does that make sense?

Bottom line, if you have low/no alternator output and the dash light is on, it's likely because your alternator has failed or failing, or your voltage regulator is bad. If you have low/no alternator output and the dash light is off, it's likely because you have a continuity issue between the dash light and the alternator, causing the alternator to simply not engage. My vote for you is for the latter.

I would start by checking all of your plugs. Sounds to me like a plug is on the cusp of continuity. See if anything happens when you lightly wiggle the plug on the alternator. Same with the bulkhead connector in the corner of the engine bay. The alternator/battery light wire is in the the lower left white plug. The specific wire is the second from the bottom on the left.

Will you be at Ken's tomorrow?

[Elvis]

Nicholas is right,

Bulb dead or wire loose.

This is exactly how the alternator is supposed to work when the bulb is dead.


Newer alternators don't always have this feature, they don't jump in anymore at higher revs.
Don't ask me why I know that ... :-)

[jawn101]

I had the same issue and it was my regulator connector. Single brown wire, right at the alternator as was mentioned.

[Doogie]

I will be at Ken's. Your description of the charging circuit makes perfect sense Nick. The more I drive this after it's 25 year sleep the more I expect to run into things like this, it's great knowing I have a full pit crew available to me! Thanks, I'll check it out tonight.

Doug

[David T]

It could be a bad connection but from your description it sounds like the brushes in the alternator because the regulator overheated and dripped goo all over the brusholder. Once it gets warm the brushes make contact but as soon as they cool (when you shut off the motor) the goo hardens again preventing the brushes from making contact. Pull the alternator and get a new voltage regulator and brusholder. The parts are under $50 and are fairly common, they fit some VW's (if it's the Motorola).
David Teitelbaum

[mluder]

Did you check voltage at the battery when the dash guage was reading low? If your getting better than 12v it could be something wrong with the dash guage or ground in the instrument cluster. That wouldn't explain the rough running engine but that could be completely unrelated.

Cheers
Steve