87oldscutty

My alternator crapped out and a friend of mine has a 78 amp alternator he bought for his cutlass and never used it. Will it be sufficient for mine. I have power windows/locks and a simple aftermarket radio and factory speakers.

Octania

yes

BILL DEMMER

and double that,

YES


bill

87oldscutty

Ok got the new alternator and to my surprise the one I got when I put on the car it was reading 12.4 volts and with a load on it reads 12.2 I am stumped. Please anyone have any suggestions.

87oldscutty

this is a new never used reman alternator that my friend never used

oldstata

I have got brand new ones that were bad .

Or you could have a voltage drop some where

87oldscutty

that is what I am getting at the stud on the back of the alternator. I had it tested at oreilly's auto parts and came back good but then I called my mechanic he said it could still be bad and called someone else and he told me he had a truck do the same thing mine was and said his was the alternator.

oldstata

I an only speaking out if experience here but I had a starter that drew to much power and would drain the battery

87oldscutty

my starter seems to work fine. I don't know what else to do

87oldscutty

I have another alternator on the way should be here Monday. Lets just hope this one works because I am at a loss.

87oldscutty

I messed with the alternator today and it FINALLY got up to 13.4 and times had over 14.0 volts coming from it. It takes a little bit but will get there it seems. What could this be? I am beyond stumped.

oldstata

What do you mean by messed with ? Played with wiring or rev the engine ? Tighten belt ?

87oldscutty

to be honest I have no idea what I did to it. it takes about a minute or so for it to start putting out over 13 volts

oldstata

Check your wires sound like you might have a poor connection or corroded wire . Best of luck

MDchanic

This isn't a "one-wire" alternator, is it?

- Eric

svnt442

Is the alternator bracket painted?

stellar

Sounds like you may have a low battery or possibly a bad battery. Charge battery full and then retest.

87oldscutty

I drove it today and seem good. I still have some squealing coming out from under the hood. When I was heading home the battery light came back on. I put my voltage tester back on it and was showing 12.5 at idle then I revved it up (not sure the rpm because no tach) it then jumped back up to 13.5-14 volts. I don't know what could be wrong. I am wondering if the water pump isn't spinning right causing the alternator to not spin properly.

87oldscutty

oh I forgot to add that when the squealing is present it is charging properly

oldstata

Sounds like a loose belt retighten it up and see what happens may need to replace if cracked or contaminated with fluids

MDchanic

Could this squealing perhaps be coming from the alternator belt?

Current scenario:
Start car: no charging, no squealing.
Rev engine: both charging and squealing begin.

So, without a doubt, you've got a loose belt, but that is not the cause of your no-charge at idle problem.

I ask you a second time: Is this a "one-wire" alternator?

- Eric

87oldscutty

It has a plug on the bottom with a brown wire and red wire. The belt is fairly new.

MDchanic

The age of the belt is irrelevant if you don't tighten it.

If your alternator connects using the stock 2-wire plastic plug, with terminals like this: (— —), in addition to the large red wire attached to the stud, then it is not a one-wire alternator, although it is acting like one.

Is this a regular stock replacement alternator, or a fancy, chrome-plated Chinese model?

My belief is that the internal regulator is not providing proper excitement to the rotor winding.

- Eric

stellar

I'm in the loose belt column now too.

MDchanic

Yes, but if the belt were loose, but tight enough to spin the alternator (as it is, because we do get voltage sometimes), it should also be spinning it at idle, and there should be some charging at idle as well.

It looks to me as though there is no charging going on at low RPMs, but when the RPMs go up, it begins to charge, the resistance to rotation increases, and then the belt slips.

Just my 2¢.

- Eric

stellar

Once the 1 wire style kick in they will continue to stay energized until the key is turned off reguardless of the rpm. Just because the alternator plug connection is open for the wires doesn't mean it isn't a 1 wire either. It could still be a 1 wire. Even if it is energized it won't charge at low rpm with a loose belt. So My thoughts are the 1st step should be tighten the belt which is obviously loose. Then see if it holds voltage at idle once the battery is charged. Then shut it off and restart and not increase rpm to see if it is charging at idle.

oldstata

I am still confused on this part ?

I would tighten belt see what you have and go from there it's very possible that the internal reg is not function properly , but you need a properly tighten belts as well

MDchanic

Stellar, I think you've laid out the diagnostic procedure for this one.

- Eric

87oldscutty

Ok I tightened my belts and the squealing is gone. I let the car run for about 10 minutes or so with the radio and lights on and every once in a while hit a turn signal and was holding over 14 volts. I put the heater on and it dropped to mid 13 and bounced around. I drove it around and the light flickered and came on fully for a couple of seconds. I went back out in it and the light came on until I put the gas pedal to the floor then it went back out. You can watch the light on the dash and you can see it come on very dim and flicker. When I get to 65-70 mph the light flickers more and comes on from time to time. I am at a loss and don't know what else to check. I should have another replacement in a day or so. I am going to change it out just to be safe.

oldstata

Okay what aftermarket electrical do you have ? Radio amp ect.

87oldscutty

I just have a Sony cd player and 2 back factory speakers. No amp. I took out the a/c compressor and lines because it was empty anyway. I don't have nothing else added too it.

oldstata

Replace it

78amp should be fine with just a radio upgrade

I would still check your wiring make sure there isn't any corrosion at splices or connection

Just wondering what was the old one charging at ?

87oldscutty

I still have the old one and when Oreillys Auto Parts put it on their test machine it came back as bad. I took the one on it now to them and it came back as good. So are you saying 78 amp isn't big enough? I have another 78 amp coming hopefully tomorrow. I checked the wires and they looked good but I didn't go all the way to the end of the brown wire because I don't know where it goes from there.

oldstata

78 is fine

The wire start to brake at the connectors at times and the under hood wires get hard and brittle . so just make sure all wires seem good give a light tug and make sure the dont brake or wiggle them and see if your readings change.

Example If you have a broken wire to the dash light it wouldn't charge because it completes the system
This just happened to me on a customers car was not charging move then 12v changed alt and it was charging 12.5v walked away it jumped up to 13v ended up being the batt light wire was broken
It happens to the best of us

87oldscutty

they all seem good and tight. I checked them and used a knife to scrape on it to make sure it was getting good contact. I don't know what else to check

87oldscutty

I will post back when the replacement alternator comes in but I am seriously doubting that its my problem but I could be wrong

Octania

My similar '85 442 misbehaved the other day, charging light came on briefly, then later came on dimly.

Within a few days, it had to be jump started if I ran with the headlights on. I ended up taking the battery out to put a known good one in, to get to work. Later, I went to charge the dead battery, it was out of water. And dead also. As in, adding water did not fix it. 7 yrs old and petered out. Since then, the charge light has stayed off, the car has not needed jump starts, and life goes on merrily. Except I will need to buy another battery for it when I get the Saturn's engine back in. I have had "maintenance free" batteries for years, forgot that the old type need to have distilled water added on occasion...

Checking the battery water level is very easy and on the must-do list for your problem.

Also, I have heard that on the G-body, if you take the AC belt off, you can have difficulty getting enough power thru the one remaining belt, with squealing being the chief complaint from that situation. Others say that, properly adjusted, the one belt works fine. Mine has the AC belt in place. It is undeniably true however that NO belt will transmit the proper level of power if it is not tensioned sufficiently.

Also, it is entirely possible for ground connections to become faulty- the G body alternator I believe has a ground wire that ensures a proper connection to the alternator body, bypassing all the mounting paint and oxidation issues. Make sure your black wire with a large [5/16"] bolt terminal ring is tied to the alternator properly- case backside.

Also, read up on the alternator troubleshooting- there is a test hole into which you stick a screwdriver or similar in order to force it to max voltage, so you can easily verify that is is capable of putting out properly.

87oldscutty

My cutlass has a fan belt and my alternator belt runs off the alternator. I'm so stumped and want to figure this out so I don't have to pay someone to do it for me.

87oldscutty

I mean water pump

87oldscutty

I don't have a wire going to a bolt on the back of the alternator. There wasn't one when I got the car.