Alternator problem

[mrzods13]

Ok a little confused bought this alternator

http://www.amazon.com/gp/aw/d/B000E6MIVO

After installing I started up the car and the car wouldn't stay running and the needle for voltage on the dash was bouncing all over. I put the old one back on no problem started up and stayed running. The alternator I bough matched and hooked up the same way.

 

[stubs300]

Sounds to me like you bought a lemon.

 

[70bigblockdodge]

Sounds like a question for Big John.


I'm guessing diodes/rectifier.

 

[mrzods13]

I figured because the old one works great, I'll tell ya amazon has gotten more parts returned back than I can count. Voltage regulator is new, wiring is in good shape.

 

[Big_John]

Internal short in the alternator is my best guess.

Either way, it sounds like you got a bad one.

I've had great luck buying stuff from Amazon, but have gotten burned a couple times buying things like parts for the washer.

 

[mrzods13]

Any recommendations on brands or a higher amp one, I have a non ac single. Should have went with rockauto

 

[1978 NYB]

Take it to AAP and they can bench test it while you watch.

 

[mrzods13]

Probably do that tomorrow

 

[70bigblockdodge]

I have had good luck at auto zone and they have no questions asked return they test it if it is bad they just give you another one, even after I may have not changed the voltage regulator and the battery cooked.

 

[mrzods13]

I figure that 50 amps is what the original one is, so It can't be overpowering anything, I might try the autozone being its around the corner and there is a lifetime warranty

 

[70bigblockdodge]

They also offer same with only one year warranty for cheapskates like me lol.

 

[commando1]

I thought I was the only one that knew of that scam...

 

[70bigblockdodge]

Never pay for a warranty, save the money go to Las Vegas every 5 or so years and piss it away there.

 

[BJS racing]

I figure that 50 amps is what the original one is, so It can't be overpowering anything, I might try the autozone being its around the corner and there is a lifetime warranty

Yeah just so you know they don't always stand behind that warranty. I was refused another new one after the 16th alternator I put on my truck in one year a few years ago. They told me that they wouldn't warranty it anymore and that there was something wrong with the wiring in my truck. REALLY? Obviously they had no idea what I did for a living! So I went and robbed one off a truck a neighbor had and drove it until the engine blew up and then put it on my duster and drove it another two years before selling it. I will not buy anything but oil and brake clean from AZ. Junk parts from people that have no clue what they are doing. I would get the alternator through O'Reily or Napa. But that is just me. I have had very bad luck with AZ and electrical parts.

 

[twostick]

I gave up on that style of alternator on my 66 after about 6 duds.

I converted it to a 60a Denso using an AR Engineering bracket kit I bought from Mancini's. I ran a cable direct from the alt to the battery and bypassed the bulkhead connection and ammeter with 8ga wire. That eliminates 95% of the reason a Mopar sets itself on fire. The alternator can be found on early Toyota 4Runners with V-belt pulley.

I think early Dakotas used V-belt Densos too that were higher output and could be easily adapted.

I had a billet bracket on the car and and discovered after I bought the kit that all I really needed was the spacers and tension bracket. And because I never compared the old spacers to the new ones maybe all I really needed was the bracket.

http://arengineering.com/products/denso-60-amp-kit-big-block/

Kevin

 

[mrzods13]

Well time to go to advance to get it tested, they don't even have the right hook up to test the alternator at autozone, these places suck. All I got was oh it matches my picture but I don't have the right connectors unreal.

 

[Big_John]

FWIW, it's really pretty easy to rebuild the alternators yourself.

The diodes are usually what is causing the problems, they aren't too hard to swap out. Change the brushes and maybe bearings (the one at the pulley gets worn, the rear one usually doesn't go bad).

You'll need a soldering iron for the diodes and a puller for the pulley if you swap in new bearings.

Starters are pretty easy too....

 

[mrzods13]

I got it tested no good ordered another one from advance and I already told the guy he's testing it before I leave the store.

 

[BillGrissom]

Too late for you, but for others. Simplest to do some simple diagnostics in the car. That round-back type is usually a "1-field wire" type, with one brush grounded to the case. Measure the voltage difference between the 2 brushes (i.e. field terminal to other brush screw). If not close to 12 V, you can't blame the alternator for not outputting current. You can apply 12 V yourself w/ a jumper wire from the battery. Can also try grounding the alt case to BATT- w/ a jumper cable. That was my problem one time, it wasn't getting a good ground thru the block bracket. Sometimes rebuilders fail to ground the 2nd brush. Check w/ an ohmeter. Some round-backs came w/ 2 field terminals around the time they were changing to the square-back (~1973?), so a rebuilt one could come that way. If so, run a jumper from the 2nd (isolated) terminal to a good ground.