Need a new alternator

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Drache

Drache

1971 Dodge Dart Swinger
Joined
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Williams Lake, BC, Canada
Ok the alternator I have in my car has been crapping out on my and needed to be rebuilt once already along with my power relay and now the diodes on the alternator needed to be replaced. The problem is the local shops all say they don't carry an alternator for my car. :wack:

Now my engine has been upgraded and so has my electrical system. Currently have an MSD Blaster coil, MSD distributor, etc. Also have an electric fan as well, car stereo, etc.

I have noticed that doing all this usually means when I put my foot on the gas that my headlights actually go brighter :D So I think I might need one with a little more "oomph" than an OEM?

So which one does someone suggest?
 
The changing headlights or discharge at idle is a very common issue that is more often in the cars overall electrical system. If the headlight wiring isn't up to par upgrading other portions of the electrical wont cure it and a 100 amp alternator may not cure it.
 
RedFish said:
The changing headlights or discharge at idle is a very common issue that is more often in the cars overall electrical system. If the headlight wiring isn't up to par upgrading other portions of the electrical wont cure it and a 100 amp alternator may not cure it.
Click to expand...

It's not just the headlights but also the dash lights as well. But the problem still occurs that Ive had to have the alternator rebuilt twice already and need a new one that can run the system I have.
 
What have you done (if anything) to the wiring?

The problem is NOT ALL "with" the alternator output ratings

If you are still running stock factory wiring, there is a couple of problems

First, the large gauge main feed wires going through the bulkhead connector WERE NEVER large enough to support large amperage loads.

Second, the connectors through the bulkhead MAY BE DAMAGED and no longer able to carry what they once could.

Third, there can be problems with the ammeter itself. Depending on the year of car, the connnections to the ammeter are a "sandwich" which sometimes has the plastic dash casting and in all years, the studs are actually loose in the ammeter "shunt." The point is, this can be an area of "bad connection."

Read up on the "deal" from Mad Electrical:

This article gives a good overall of the simplified circuit path and why this is a problem:

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

Next, some of the older model Mopar alternators don't put out very well at lower RPM, it's simply the design of the beast. This is why you see people going to stuff like "Denso" alternators. Just going to a later model Mopar ("square back") can help

SPEAKING OF WHICH if you are still using a 69/ earlier (single field wire) Mopar alternator, you DO NOT need to do so. Even if you are using your stock factory pre-70 regulator, you can use a later model Mopar alternator which has TWO field terminals (isolated field, incorrectly called "dual field.")

All you need to do is ground either field terminal, and hook up as before.

what this means is, you can use ANY Mopar common frame alternator well up into the 80's.
 
It is all just a guess without some measurements. Could be a wiring issue, or an alternator output issue - or both.

Grab your voltmeter, and check the following:

Engine off, battery resting voltage at the battery terminals.

Engine running at idle, no additional loads (lights off, no audio, etc)
Voltage at the battery terminals
Voltage at the alternator output stud
Voltage at the fuseblock or cigar lighter

Run the engine up to 1800+ rpm, no additional loads
Voltage at the battery terminals
Voltage at the alternator output stud
Voltage at the fuseblock or cigar lighter

Return the engine to idle. Turn on the headlights. Run your audio as you normally would
Voltage at the battery terminals
Voltage at the alternator output stud
Voltage at the fuseblock or cigar lighter

Run the engine up to 1800+ rpm, with the headlights & audio
Voltage at the battery terminals
Voltage at the alternator output stud
Voltage at the fuseblock or cigar lighter

That old chrysler alternator design was cutting edge in it's day - nearly 50 years ago. They gave up on it in the 1980's when electrical loads passed it's capacity. Ford & GM both had changed alternators significantly as well All of those older designs (Mopar, Ford 1G Delco 10SI) were 40 amp units to start, and the final units were 60 to 100 amps - with no reserve capacity. The next generations were 90+ amps to start with in the 1980's... and now a Viper alternator is a 180+ amp unit.

Depending on what you are running for audio, you may need a much larger alternator. How many watts?

Amps and Volts are both equally important important measurements in diagnosing automotive electrical systems. Run the voltage checks, and post the results. We can help you find the problem.

B.
 
When you repair/replace the alternator, make sure you test the regulator as it could be the alternator killer too along with the previously mentioned overloads and bad connections. If you have a megapower sound system, you'll probably have to rewire the car in a heavier gauge and get a higher output alt/reg. You haven't been testing the alternator output by pulling off the battery cable while the engine is running have you? That is a common diode killer.
 
cudamark said:
You haven't been testing the alternator output by pulling off the battery cable while the engine is running have you? That is a common diode killer.
Click to expand...

Good point. I've been preaching this for years. This is an old wives' tale that needs to get buried.
 
I was having NO problems at all before putting this new alternator in (no lights dimming at all). Thus why I thought it was the alternator. Not to mention the damn thing just keeps breaking. I have done nothing at all with the alternator and this diode thing happened only after driving the car 6 times after getting the alternator rebuilt the last time.

Now if I don't need one with more output then can anyone suggest a decent alternator then? I'd rather replace this one before I need to get it worked on again.
 
Don't really know what you might need. Your problem could be the alternator, wiring, a regulator, a bad battery... or a 6,000 watt audio system.

Or all of it.

That alternator series has been out of production a long time. Rebuilt stuff can be a real roll of the dice.
Piles of old alternators are torn apart, and "good used" parts are binned up on the shelf. You might get a set of diodes that is 40 years old & tests "ok" put right back in. Sure, new bearings & brushes, but that is it.
Parts like a blown out stator? Well, they put that stator in a big oven, and burn all the insulation out of it. Then they yank the copper put of it & rewind it with new wire. The oven trick saves time, but hurts the stator laminations some - they lose about 10% of their magnetic properties.

Cases? Well a spun bearing gets replaced with a new bearing & some loctite. Some of those cases at a rebuilder's shop have been reused several times, just dumped in the tumbler each time. Rotors? Well, slip rings get replaced, but 40 year old windings stay inside. Rotor coils are a huge pain to replace.

So now you have bins of parts that may or may not be right. Perhaps a 37amp rotor assembled with a 60 amp stator. Charges not so well. Or a 60 amp rotor in a 37amp stator - charges great at idle, but maxes out @ 40 amps, so the alternator can't keep up with A/C + Wiper + Headlights.

Maybe you just got a set of 37 amp parts. Or a bad diode. Or you have a wiring failure getting worse. There is simply no way to say for sure from the words "dim lights". You can keep throwing parts at it, or diagnose the problem before buying more parts.

If you are running a killer audio system, and want more alternator there are several good choices. All of them require modifications and or upgrades to be installed properly.

B.
 
The alternator I have now was purchased at a local autoparts store (Canadian Tire actually). Told him what I had and he looked in their computers and went to the back to pull a brand new one off the shelf.

But after how this one turned out I dont want to pick up another from them and was looking for something better.
 
Well, if you got a Brand New unit, you have a chinese copy of a squareback. You should still have your core too, since there should be no core collected on a a new part.

You want "something better". Other than a custom unit assembled in a mopar case, "better" means a different alternator - and some bracket work.

How much audio do you have in the car?

What does your electric fan draw?

What are your system voltages right now?

What battery are you running, and where is it located?

There are alternators out there that make more power at idle than the OE unit did at 4000 engine rpm.

Which way you go upgrading the charging system depends on what you expect of it, and how much fabricating you want to do. And how much you have to spend.

How much alternator do you want or need? 100 amps? 200 amps? More?

B.
 
By better I was simply meaning maybe a better brand. Although come to think of it I seem to remember the Alternator was Bosch brand? Have to find the box.

I dont know anymore. Im just been having a lot on my plate and dealing with car troubles isn't something I have time for right now. Im sorry if Im coming off as an asshole.
 
Drache said:
I was having NO problems at all before putting this new alternator in (no lights dimming at all). Thus why I thought it was the alternator. Not to mention the damn thing just keeps breaking. I have done nothing at all with the alternator and this diode thing happened only after driving the car 6 times after getting the alternator rebuilt the last time.

Now if I don't need one with more output then can anyone suggest a decent alternator then? I'd rather replace this one before I need to get it worked on again.
Click to expand...
What changes have been made electrically since your previous "good" alternator was in the car? Maybe you can have it rebuilt by a local auto electric shop. They may be able to determine how much output will be needed for your particular application. A low output at idle is not uncommon on the early, low output alternators and point regulator setups. It usually doesn't hurt anything unless you have a huge enough draw to make the engine die. Once you get underway again, the charging system should recover and replace anything drawn from the battery. I mentioned the alternator pulley diameter because I've seen some cases where the replacement alternator had a much larger pulley than the old one and made that situation worse because the new unit was spinning even slower.
 
The oversize pulley issue is also caused by the "good enough" commercial rebuilders. Just an unfortunate fact of life any more. Slightly harder to deal with because the chrysler alternator has a pressed on pulley.

Chances are it was a rebuilt unit if they collected a core or charged a core fee. Companies like Delco & Bosch contract with a regional rebuilder to handle their parts, and they supply pre-printed boxes for the parts.

It is always better to have your old unit repaired by someone you can look in the eye. Not always possible, and I understand that.

WAI makes a new unit they call a "revised square back" 78 amps, 1 groove pulley Part number 7024N Actually not a bad part for an import. All new parts, no rebuilt.

Since you are in Canada, I can't tell you who to ask for one locally. I can give you contact info for a US vendor that will ship USPS to Canada for about 35 bucks freight on an alternator. Or you can call WAI canada and ask if they can point you at a local source 514-324-7922

Hope that helps.

B.
 
cudamark said:
What changes have been made electrically since your previous "good" alternator was in the car? Maybe you can have it rebuilt by a local auto electric shop. They may be able to determine how much output will be needed for your particular application. A low output at idle is not uncommon on the early, low output alternators and point regulator setups. It usually doesn't hurt anything unless you have a huge enough draw to make the engine die. Once you get underway again, the charging system should recover and replace anything drawn from the battery. I mentioned the alternator pulley diameter because I've seen some cases where the replacement alternator had a much larger pulley than the old one and made that situation worse because the new unit was spinning even slower.
Click to expand...

The only thing that changed personally was swapping from the old distributor to an HEI one.

As for the old distributor sadly it was taken out of the trunk of my car by persons unknown.
 
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