Alternator Woes

[mrbill3]

Yesterday I got in the XJ, started it up and went down the street and everything was fine. I stopped at the corner to wait for traffic to clear so I could turn left. When I hit the gas to go, it started to miss and was running real sluggish. I looked down at the dash and noticed that my voltage guage had not moved. It was still at zero. I also had no turn signals. I managed to limp home and checked it with my multi-meter and had no output from the alternator. I ripped it out and went over to Kragen(the closest place) and bought a new one, took it home and slapped it in. When I fired up the the motor and drove it around the guage was back up to just under 14 volts. That was about 6:00 pm. Today when I went to go to a local concert, I started it up and left and the guage only went up to about 12 volts. When I got home I check it with the multi-meter, it was only reading 11.34 volts. Me thinks me got a bad replacement. What do you guys think? :gonnablow

[XgeekstarX]

do they have a bench tester?

[mrbill3]

Actually they do and I was going to drive it there today but, when I went to leave the house this morning the guage went back to zero and it started running like crap again. I guess after work I will tear it out again and take it over to have it tested/replaced.

[mrbill3]

I had the alternator tested and it was bad so they exchanged it for one that tested good. They also tested my battery. It tested good and just needed a bit of a charge. I Installed the new alternator tonight and the guage reads about 14 volts and the multi-meter reads 14.27 volts. I guess I'll see what happens tomorrow when I leave for work.

[5-90]

I ripped it out and went over to Kragen(the closest place) and bought a new one, took it home and slapped it in.

Kragen - there's your mistake. I wasted three and a half years there - the failure rate for alternators sold typically ran somewhere between 60-120%.

That's why I try to go to smaller shops - rather than get something that may not have been tested after assembly then knackered about during shipment (on several legs...) I end up dealing directly with the man who does the rebuilding AND the testing, and I can tell him what I need - then get it.

Even if I pay more than I would at a chain store (I don't, usually...) it's worth it just because I get an "install and forget" part that I don't have to replace four times before I get one that works. Spend a few extra bucks, and save three hours on replacement jobs - I'll take it. Saving time is usually worth a few bucks extra to me - so I'm willing to spend a little more on parts I know to be good.

5-90

[mrbill3]

Kragen - there's your mistake. I wasted three and a half years there - the failure rate for alternators sold typically ran somewhere between 60-120%.

That's why I try to go to smaller shops - rather than get something that may not have been tested after assembly then knackered about during shipment (on several legs...) I end up dealing directly with the man who does the rebuilding AND the testing, and I can tell him what I need - then get it.

Even if I pay more than I would at a chain store (I don't, usually...) it's worth it just because I get an "install and forget" part that I don't have to replace four times before I get one that works. Spend a few extra bucks, and save three hours on replacement jobs - I'll take it. Saving time is usually worth a few bucks extra to me - so I'm willing to spend a little more on parts I know to be good.

5-90
While I agree with you, Kragen is the only parts store in town (NAPA closed about 2 years ago). When I used to live in San Jose (in Willow Glen) I, like you, used to go to San Jose Generator. If this second replacement hadn't worked I would have come up ther to get one. It's difinately worth the extra $$. I never had a problem with anything I bought/took in there. There are some things I miss about the "Big City" ,but not enough to move back there. For example: today's temp in San Jose=98, Temp here=75and no smog...need I say more? :gonnablow

[5-90]

Which is why I plan to unass CA entirely in a few more years - once I finish school and get a few things out of the way.

I have since talked SJG into doing mail-order - see my site for info. I need to touch base with him and make sure the pricing I have is still current, tho...

Link's in my sig.

5-90

[mrbill3]

Which is why I plan to unass CA entirely in a few more years - once I finish school and get a few things out of the way.

I have since talked SJG into doing mail-order - see my site for info. I need to touch base with him and make sure the pricing I have is still current, tho...

Link's in my sig.

5-90

Thanks, I wish I had seen that before. Next time I'll either drive up there In my other vehicle (BMW 325 for when I want to go fast around corners :roll:) or do the mail order thing.

[Gnat5680]

just to use this thread to my advantage, do most places do alternator testing for free or do you have to pay?
i think my is going bad also. won't start and barely gets to 12 volts.

[acrid]

just to use this thread to my advantage, do most places do alternator testing for free or do you have to pay?
i think my is going bad also. won't start and barely gets to 12 volts.


that depends, have you tested your battery, charged it fully and checked after a drive. cleaned and inspected the alternator?

if you go to most places, they will test for free, test at idle and at throttle and also lights on a/c on to check operation at all levels of use. the idea being that you'll spend the money right then to fix it.

i've rescued some ill cared for alternators with wd40 and electric contact cleaner.

it can only be three things, electrically speaking.

1. a short in the system
2. a dying battery
3. a dying alternator.

[Gnat5680]

i used a tester that you plug into your lighter and it said my battery is dead( which i was going to replace anywas) and the alternator is normal/ too low. so i will be replaceing the battery shortly after i start my new job.

[5-90]

i used a tester that you plug into your lighter and it said my battery is dead( which i was going to replace anywas) and the alternator is normal/ too low. so i will be replaceing the battery shortly after i start my new job.

Piffle. If there's one thing I've noticed over the years, it's that the voltage at the lighter socket will ALWAYS be lower than system voltage - don't trust it!

Instead, get a decent DMM (if you don't have one already) and check voltage at the battery terminals with the engine running and not. Repeat at the alternator output terminal on the back, since internal corrosion at that lead will cause trouble. Last, check it AGAIN at either the start relay screwpost (RENIX) or PDC input post (HO) - and make sure all three values are "nominally" equal. What's "nominally" equal? Figure +/- .2VDC of each other, and you'll be fine (this will allow for terminal and connection losses. If you have internal corrosion on any wire, you'll see a lot more than .2VDC difference...)

The "easy way" - usually isn't.

5-90

[langer1]

the failure rate for alternators sold typically ran somewhere between 60-120%
Huh? over 120%.
You should have spent the 3 years in high school.

[RedHeep]

I think Jon is accounting for one customer having multiple failures.

So if 5 customers have 6 total failures (returns), 120% of them failed.

Or he just can't count.

[langer1]

Actually I did not read who posted that, sorry for the flame 5-90 I'm sure I missed your point.

[5-90]

I think Jon is accounting for one customer having multiple failures.

So if 5 customers have 6 total failures (returns), 120% of them failed.

Or he just can't count.

Correct. Multiple failures with a single customer can and WILL result, mathematically, in a failure rate of over 100%.

I did spend three years in high school - at least, I wanted to. I actually spent three and a half, and graduated early. I wanted to graduate earlier, but I only needed ONE course, and they wouldn't let me take it in summer school - so I spent my seventh semester "bored and destructive."

5-90

[langer1]

Correct. Multiple failures with a single customer can and WILL result, mathematically, in a failure rate of over 100%.

It could also mean a very bad Mechanic.