Bad Alternator?

[jzdude]

My car wouldn't start two times after it rained. I thought it was the rain that probably shorted something... but that was a red herring. The common denominator was that a lot of accessories was turned on (headlights, defroster, and windshield wipers). So I did some tests with a voltmeter.

Car On, Load: Radio
14.5 V
Car On, Load: Radio, Windshield Wiper, Heater, Headlights
12.05 V

Does this mean I have a bad alternator? Is it the whole alternator or just one part of the alternator like the brushes? I saw the "How To" on replacing the brushes while the alternators still in the car. I haven't replaced an alternator before so if anyone knows any short cuts please tell me :).

[Dr_Snooz]

Does your charge light come on?

[jzdude]

Does your charge light come on?

No.

[2drSE-i]

No.

Take it down to any parts store and have the battery, alternator and starter tested. If the battery reads less than 390 CCA, replace it. If the alternator puts out less than 30 amps (with no extra accessories running) replace it. Starter tests aren't as easy, they test the draw on the battery and its a judgement call from there.

[jzdude]

I don't think anything is wrong with my starter or battery. If I drive around with only a few of the accessories (only headlights & radio) on I think it works ok. When I jumped the car, drove around for 30 minutes, and left the car alone for a day, I was still able to start the car (no accessories on).

[carotman]

It's only a matter of how much the alternator charges VS how much curret you're drawing. The alternator has to charge more than what you're consuming.

The charge light should come on if you're drawing more current anyway...

[Dr_Snooz]

I have found the free Autozone tests to be fairly unreliable. They often lead to the replacement of perfectly good parts, which is expensive. You'll be a lot better off if you learn to diagnose this stuff yourself. Here are some vids from Eric the Car Guy to get you started.

https://www.youtube.com/watch?v=3QiKyjWWiRo
https://www.youtube.com/watch?v=ZuumBVz6WOM
https://www.youtube.com/watch?v=zdIKNnwEjIs
https://www.youtube.com/watch?v=nQysE2oJAuo
https://www.youtube.com/watch?v=FTGz0PKIl84

[seancmadison]

Maybe wrong thread but i have a light dimming problem go below 2,000rpm and raido is on offo on off then lights dim the same wile driving at diffrent rpm. I believe i posted elsewhere on this fouram complaining about by 3g lights were not bright enough. Today after high rpm s charge light going on i replaced the belt and after my battery was dead. Jumped it drove home with my lights diming at lo rpm and no bat. Light at high rmp after the belt change. Has a new battery and never went dead before belt change weard i know a but i dont wanna do a altanator on this car i already put a $200 starter and that was the easy side

[Legend_master]

Sounds like the alternator is bad, it's not that difficult to replace.

[Dr_Snooz]

x2 on alternator. Have you checked to see what the voltage is at idle?

[seancmadison]

Not that difficult on a fuel injected or carb. Cause i got a 2brl

[seancmadison]

Would check voltage but idle kills my battery

[Dr_Snooz]

We need numbers.

[Legend_master]

Not that difficult on a fuel injected or carb. Cause i got a 2brl

Well to answer that, it is mounted in the same place. I'm pretty sure you can get it out without removing the intake manifold.

[Oldblueaccord]

There is a 3 page thread in this section on alt trouble shooting. Without voltage AND amperage readings its very hard to know whats going on.

One thing we want to stear away from is that "a running car never discharges". Even in a modern day system like my wifes 2010 a car can still discharge a little with a full electrical load on at low RPMS. My old IH truck discharges at idle in traffic all the time,it has an amp gauge. That is what the battery is there for.

In your case I suspect its the heater blower motor. When the brushes wear the motor can pull excessive current and is fused very very high. The wires will melt before any fuses will blow.

[lostforawhile]

The system should be at least 13 volts above idle with accessories on, the alternator is 60 something amps, one issue is the power lead wire from the alternator is undersized, and overtime the crimped connections go bad,its 8 gauge and really should have been 6, the brushes also go bad and this will reduce current output, if your alternator has failedor battery is. Bad, they both might need to be replaced, a bad battery can kill. A new alternator

[swbat55]

Take ur battery to Kragen dude or another auto parts store. they can test it to see if there is juice in it and if it is holding a charge. Ur alternator is probably bad though because Ive had the exact same problem except mine ended up dying while I was driving and I had to get it towed. I replaced it myself so if you need help PM me dude. I have an 1989 accord lxi

[Oldblueaccord]

There is a 3 page thread in this section on alt trouble shooting. Without voltage AND amperage readings its very hard to know whats going on.

One thing we want to stear away from is that "a running car never discharges". Even in a modern day system like my wifes 2010 a car can still discharge a little with a full electrical load on at low RPMS. My old IH truck discharges at idle in traffic all the time,it has an amp gauge. That is what the battery is there for.

In your case I suspect its the heater blower motor. When the brushes wear the motor can pull excessive current and is fused very very high. The wires will melt before any fuses will blow.


http://www.3geez.com/forum/technical/79244-charging-system-some-other-issues.html



http://www.3geez.com/forum/technical/77887-cooling-fan-resistance.html

Post below have some amp draw voltage readings to help you out.

#56 #153 168# #189

[seancmadison]

Well to answer that, it is mounted in the same place. I'm pretty sure you can get it out without removing the intake manifold.


So it did turn out to be alt. Bad barring witch is why i still got a charge but not at high rpm. So mr. Easy to remove. The bolts and wires are a snap. Now get the damb thing out of the car. Book said remove drivers axle hahaha ya right for a alt. No so i removed uper motor mout bolts and jossiled the motor back and forth till the alt fell out. With out moving the motor the alt never would have came out all you spoiled efi guys have a huge air box that removes and us 2bbl carb guys have 2-4 extra inches on our intake. Making the only way to remove alt. Is removing drivers axle or taking off intake or the better way loosen motor mounts and move the motor out of the way.

[Dr_Snooz]

Supposedly, it's possible to snake it along the back of the engine against the firewall and remove it from the passenger side without a major teardown.

[seancmadison]

Supposedly, it's possible to snake it along the back of the engine against the firewall and remove it from the passenger side without a major teardown.

It wouldnt theres a huge tranz mount and the top motor mount is so much more visible and the mount you need to remove. It was a well working last resort and im glad i did it. The motor is required to move a lot more than a few inches.

[Dr_Snooz]

I haven't tried it as I have an injected model. That's just what some of the carb guys here have said. Glad the car is working.

[poorman212]

Yes, it does come out from the pass side.....86 DX, 87 LX, 89 LX are cars I have owned that I have done this on. If you pull the hose(s) off the heater core, even easier but not required.

[lostforawhile]

mine isnt bad, of course its where the AC compressor was, All I have to do is pull the radiator