Alternator going bad?

[-=Jeff=-]

What are some of the signs?

I noticed today when I get on it at about the 5K RPM the voltage meter on the dash starts to drop (enough to see it move) not sure what voltage it drops to..

otherwise all seems fine.. Do I need to get a replacement again?

[LGAFF]

volts being all over is a definite sign its going, check your batter terminals first make sure its tight

[LGAFF]

or might be all of the high tech gadgets you are running in your car zapping the power

[-=Jeff=-]

Sure if it all over the place, but the Needle stay put until the RPMs climb past 4K, then the voltages fall, as soon as the RPMs drop it is fine.. I doubt the 12-5v ps I added is causing the issue.. Many people are using it.. Guess I will buy an Alternator to be safe

[LantanaTX]

Sure if it all over the place, but the Needle stay put until the RPMs climb past 4K, then the voltages fall, as soon as the RPMs drop it is fine.. I doubt the 12-5v ps I added is causing the issue.. Many people are using it.. Guess I will buy an Alternator to be safe

Most parts stores will check the charging system for free and put a load on it. I would do this before just throwing money at it.

[-=Jeff=-]

Most parts stores will check the charging system for free and put a load on it. I would do this before just throwing money at it.

Yeah but having a spare is always a good thing.. might buy a higher output one that was shown on here awhile back

[Blue Flame Restorations]

When mine went out of my 9500, 95, the battery light came on the display eventually.

Evidently, the car had not had a battery tender on it for some time. It does now, always.

[WVZR-1]

What are some of the signs?

I noticed today when I get on it at about the 5K RPM the voltage meter on the dash starts to drop (enough to see it move) not sure what voltage it drops to..

otherwise all seems fine.. Do I need to get a replacement again?

You want to check the complete electrical "on the car" using a "Carbon Pile" load tester and a DMM. That's the only way to actually evaluate the system and it should be done before doing any alternator/generator OR starter replacement.

[-=Jeff=-]

OK, get down to 11 volts when at 5k rpm

Below that rpm it is high 12s, I will data log to a file next time

[scottfab]

OK, get down to 11 volts when at 5k rpm

Below that rpm it is high 12s, I will data log to a file next time

Battery V should be at 14.5v or so at idle if alternator is doing it's thing.

[WVZR-1]

OK, get down to 11 volts when at 5k rpm

Below that rpm it is high 12s, I will data log to a file next time

You do seem to have issues either with the alternator or gauges! The load test is the only check and done on the vehicle. It could be the exciter wire OR maybe even a belt slip. I believe without looking you should be able to apply manual tension at the tensioner while running and see if that improves the charge rate.

LOAD TEST ON CAR - A little math and you'll know. All else is foolishness. You could do numerous replacements and until properly diagnosed still have issues.

[scottfab]

There is simply no need to do any kind of load test if the V on the battery is not right at idle. You can stop right there.
A load test is only indicated if at least 14V or greater is not seen at the
bat at idle. Also load tests don't need a carbon pile or a DVM.
A simple nicrom (nickle chromium wire) and analog gauge is fine.
Harbor Freight sells them.
Not belt slipping either unless you're hearing load squeaking.
Squealing was not mentioned.

Do the easy things first. V right at the battery at idle.
Sadly, based on experience it does sound like alternator.
Yet, doing due diligence is suggested.

[WVZR-1]

Not belt slipping either unless you're hearing load squeaking.
Squealing was not mentioned.



Doesn't need to "squeal"!

[scottfab]

Doesn't need to "squeal"!

I suppose that could be true, however if the the tensioner pulley has failed or is weak I'd expect the power steering to show significant lose of power and that is plain scary (been there).
Sure hope it is something simple like a loose belt for his sake.
Much easier to deal with.

[WVZR-1]

I suppose that could be true, however if the the tensioner pulley has failed or is weak I'd expect the power steering to show significant lose of power and that is plain scary (been there).
Sure hope it is something simple like a loose belt for his sake.
Much easier to deal with.

The spring in the tensioner fails/weakens and the arm then just flutters along at higher RPM's and the pulley isn't able to maintain a consistent tension on the belt. I believe that the relationship of the alternator pulley to the tensioner and the lesser diameter of the alternator pulley would be more suspect than the much larger diameter of the P/S pulley and it's relationship to the tensioner.

If the number he's posted are "factual" then there's certainly every indication that there's electrical system issues. He mentioned a "spare" isn't a bad idea - well it is when you unbox the spare months after the buy and it's a DUD in the box. I believe that with the price of the parts and the simplicity of the OE/GM unit if I had an OE/GM unit on it I'd much rather a repair than an off the shelf reman from Joe, John, Jim or Frank!

The connector at the alternator is as likely a candidate for failure as anything internal on the unit maybe.

[-=Jeff=-]

tensioner is new(er) maybe 3K miles.. I NEED to drive it with my datalogger on it to verify the data. when I drove it yesterday, I saw the gauge fluctuate. when I drove it a second time, I used my datalogger but I did not record, just viewed the data, that is when i saw it fall to the 11v mark.. the Alternator was last replaced in Jan 2010.. it was an AC Delco purchased @ Rock Auto..

I will check connections, and log data when driving the car and I will look for my old alternator as well.. I will keep an eye on it, like I said cruising around town it seems fine, it just seems to be an odd occurrence and i was just looking for some actual info as to IF the alternator could be the cause..

thanks for all the info so far

[scottfab]

The spring in the tensioner fails/weakens and the arm then just flutters along at higher RPM's and the pulley isn't able to maintain a consistent tension on the belt. I believe that the relationship of the alternator pulley to the tensioner and the lesser diameter of the alternator pulley would be more suspect than the much larger diameter of the P/S pulley and it's relationship to the tensioner.

If the number he's posted are "factual" then there's certainly every indication that there's electrical system issues. He mentioned a "spare" isn't a bad idea - well it is when you unbox the spare months after the buy and it's a DUD in the box. I believe that with the price of the parts and the simplicity of the OE/GM unit if I had an OE/GM unit on it I'd much rather a repair than an off the shelf reman from Joe, John, Jim or Frank!

The connector at the alternator is as likely a candidate for failure as anything internal on the unit maybe.


Well, while we're speculating and until we hear the actual verdict of what it is, I have to say:
1. I've had a "weak spring" in the tensioner pulley. It had no effect on the alternator. The power steering would be the first heads up AND it squealed big time.
2. I've had an alternator failure which exhibited this (his) same symptom. It was not a loose field winding lead.
3. I keep spares of most major components. Not a bad way to go at all especially given what prices of components are doing.

[-=Jeff=-]

I might have my OE Alternator I replaced in 2010, I am debating on rebuilding it

[WVZR-1]

Jeff - I mentioned the load test and I used the term "EVALUATE" in my first post and that was only because of the numbers you posted. The rest of the thread is maybe of little value but with 25 year old wiring I can't imagine why an "evaluation" wouldn't be wise. Here's a Delco/Remy (NOT ACD) newsletter from 2013 that's quite basic for all the load tests. It's the way it's been done for years when a complete diagnosis was desired or by fleets, municipalities and others that concern themselves with maintenance. A quality electrical repair shop does the same to "evaluate" unless there's obvious issues.

I would think a read of the newsletter might be of interest. The procedures in this read are quite basic:

http://www.delcoremy.com/Delco-Remy-Connect-Online-Newsletter/June-2013/June_2013_DelcoRemyConnect.aspx

There's also instances where excessive loads and the older/lower output alternators do precisely what you mention yours doing. Replacement with higher amperage output alternators has generally been a correction in those cases.

I believe the CS144 can be built to as high as 200 AMP configurations.

[-=Jeff=-]

WV thanks,

Yes I will evaluate the car and wiring, but I am also looking for at options (parallel tasks) instead if waiting until I can confirm the issue, I was researching what I can do for the alternator, I am quite sure the OEM output is limited especially with my aftermarket stereo. Hopefully will get time to look it over

[scottfab]

I might have my OE Alternator I replaced in 2010, I am debating on rebuilding it

If, when you measure the V at idle and if you determine that the alternator is the "obvious" issue, here is a link for rebuilding our specific alternator. I did this rebuild and link about 12yrs ago. It is
very doable.

120amp Alternator Re-build (http://www.zr1netregistry.com/Information/TechNet/Electrical/tabid/113/articleType/ArticleView/articleId/28/Alternator-Rebuild.aspx)

I really hope is something easier.
The absolute worst thing that could happen to you now is that the problem is intermittent and all works fine now only to fail on a road trip
like it did for me :cry:

[-=Jeff=-]

so the threads on my old alternator are boogered up.. Along with the front bearing being trashed..

I think what I may do is pull the alternator off and inspect it after doing other checks.

Once off I may just rebuild it, I found the Regulator, Rectifier and Stator that will boost it to 140 Amp, which I had in my 89 without issues.

I have found that even Remanufactured ones don't last..

just need to order the parts

[scottfab]

so the threads on my old alternator are boogered up.. Along with the front bearing being trashed..

I think what I may do is pull the alternator off and inspect it after doing other checks.

Once off I may just rebuild it, I found the Regulator, Rectifier and Stator that will boost it to 140 Amp, which I had in my 89 without issues.

I have found that even Remanufactured ones don't last..

just need to order the parts

Great idea on the 140amp setup. I'd suggest two things.
1. Test the new bearing by hand before assembling it on. It should roll freely and pay attention to the feel when you roll it. ANY vibration when rolling it slowwwwwly is susptect. Sometime back many kits were shipped with a faulty rear bearing.
2. Test the completed assembly at O'riely's or such place BEFORE putting it back in the car.

[-=Jeff=-]

Great idea on the 140amp setup. I'd suggest two things.
1. Test the new bearing by hand before assembling it on. It should roll freely and pay attention to the feel when you roll it. ANY vibration when rolling it slowwwwwly is susptect. Sometime back many kits were shipped with a faulty rear bearing.
2. Test the completed assembly at O'riely's or such place BEFORE putting it back in the car.

Thanks for the tips.. I will probably rebuild the one on the car, since the OEM one I have will need a new rotor..

[WVZR-1]

Thanks for the tips.. I will probably rebuild the one on the car, since the OEM one I have will need a new rotor..

You might try a JY 140 AMP for a build of your own! You guys have a quite good contact I thought pretty local. '93+ had a 140 AMP option for the LT1 - KG9. An OE core I'd think real cheap. Later trucks also if there's a local JY to help you. Your concern is just the internals. Which threads are messed up on your OE?

[Tony Davila]

Rebuild your factory alternator if you can and DO NOT loose the original pulley.

The factory pulley is larger than what you will get on a exchange alternator from any auto part stores.

[-=Jeff=-]

You might try a JY 140 AMP for a build of your own! You guys have a quite good contact I thought pretty local. '93+ had a 140 AMP option for the LT1 - KG9. An OE core I'd think real cheap. Later trucks also if there's a local JY to help you. Your concern is just the internals. Which threads are messed up on your OE?

Rotor the end where the pulley goes... then need to get the roto off that side of the case as that bearing is toast


Rebuild your factory alternator if you can and DO NOT loose the original pulley.

The factory pulley is larger than what you will get on a exchange alternator from any auto part stores.

Yep, I noticed that, what is the down side of running the smaller pulley? I know it is a bit easier to swap the belt :D

[scottfab]

....snip...
Yep, I noticed that, what is the down side of running the smaller pulley? I know it is a bit easier to swap the belt :D

Our redline is higher that standard GM engines.
That kind of spin up speed on a tiny pulley is wasting HP and ages components (bearing) faster.
Some even go so far as to run oversize pulleys to reduce HP leaching.

[-=Jeff=-]

You might try a JY 140 AMP for a build of your own! You guys have a quite good contact I thought pretty local. '93+ had a 140 AMP option for the LT1 - KG9. An OE core I'd think real cheap. Later trucks also if there's a local JY to help you. Your concern is just the internals. Which threads are messed up on your OE?

There are 2 different styles for the CS-144.. the Lt1 is the later style case and will not fit (I tried)

I am going to buy the 140A parts for my Alternator and rebuild it..

[WVZR-1]

There are 2 different styles for the CS-144.. the Lt1 is the later style case and will not fit (I tried)

I am going to buy the 140A parts for my Alternator and rebuild it..

I understand the different CS-144's BUT you're just needing the 140A internals actually only the stator I believe will do because all of the service rotors are the same. Were the originals? I don't think so but I've never researched it much. I believe it would be good to have both the 140A rotor and stator.

[-=Jeff=-]

I bought a 140A Stator and a rebuild kit ( Bearings, brushes, rectifier and regulator) with a few bit and pieces.. I will assemble everything in the one Alternator I have apart.. then assemble when I get the one off the car.. unless I find a good price on a failed one (I need the rotor and a way to get mine off the housing

[scottfab]

I bought a 140A Stator and a rebuild kit ( Bearings, brushes, rectifier and regulator) with a few bit and pieces.. I will assemble everything in the one Alternator I have apart.. then assemble when I get the one off the car.. unless I find a good price on a failed one (I need the rotor and a way to get mine off the housing

Please take pics and keep us informed how it goes. I am interested in the 140A version as I have a spare to rebuild.
As posted before, I did a rebuild with a kit with lower amp diodes.
Alternator Rebuild (http://zr1netregistry.com/Information/TechNet/Electrical/tabid/113/articleType/ArticleView/articleId/28/Alternator-Rebuild.aspx)

[-=Jeff=-]

yeah I am looking forward to getting the pieces

[-=Jeff=-]

Please take pics and keep us informed how it goes. I am interested in the 140A version as I have a spare to rebuild.
As posted before, I did a rebuild with a kit with lower amp diodes.
Alternator Rebuild (http://zr1netregistry.com/Information/TechNet/Electrical/tabid/113/articleType/ArticleView/articleId/28/Alternator-Rebuild.aspx)

what size wrench for the front keepers? that has to come off/ loose before removing the rotor?

[WVZR-1]

I bought a 140A Stator and a rebuild kit ( Bearings, brushes, rectifier and regulator) with a few bit and pieces.. I will assemble everything in the one Alternator I have apart.. then assemble when I get the one off the car.. unless I find a good price on a failed one (I need the rotor and a way to get mine off the housing

If you find a later core you want to look for a "tapered collar" that was used for pulley retention. A conventional attempt to remove with a puller will only tighten the grip. Later Cadillac and few trucks I believe. You would see it when the nut is removed.

[-=Jeff=-]

later rotor will not work due to the difference of bearings in the back housing

[WVZR-1]

later rotor will not work due to the difference of bearings in the back housing

Yes I believe the later rotors had 17mm shaft and you could use an earlier rotor in them with a bearing race but of course not the other way. I had a couple technicians that always built their alternator needs from my cores for their personal use and I had a pretty good understanding of the internals for many years. In '92 we quit offering pieces for anything newer and everything was a "hands on" for familiarity.

In about an hour maybe just a bit more they'd have an alternator built from 2, have it checked and I'd have my cores back assembled. I don't remember buying an alternator for myself either. Used a few new parts but never an alternator.

It's also difficult to relate to early and late CS144 because all LT5's are referred to as early but on the drive end only a '90 is shown as having the bearing retained by the three screw plate and '91 is show as using the other style retainer with no screws when you break down the production number. I'd be interested in having a production number directly off of a '95 alternator (not a service number but a real production one). There's the rotor dimension, the spacing either 89mm or 93mm I believe of the center to the foot mounting hole also to be considered for some. Then when the battery was moved inside the car on the Cadillacs and Oldsmobiles the regulators changed because of the cable run.

[FU]

Dave (WVZR-1) your incredible.

[-=Jeff=-]

Alternator died in it today. good thing I was a mile from home..

gauge dropped to about 10ish volts and stayed there, guess my ZR-1 will NOT be at Marc's on Sunday

[XfireZ51]

Alternator died in it today. good thing I was a mile from home..

gauge dropped to about 10ish volts and stayed there, guess my ZR-1 will NOT be at Marc's on Sunday

So now you know.

[-=Jeff=-]

yes I do.. bummer, If I have time I will pull it and get it tested (curious what failed)

I will be at Marc's on Sunday with Alex, if my parts come by Friday, I can be there with the Z otherwise no such luck

[-=Jeff=-]

Had it tested.. They test 3 parts, failed all 3, not sure if it once it fails one it fails all or not though

Hoping my parts get here soon

[WVZR-1]

Had it tested.. They test 3 parts, failed all 3, not sure if it once it fails one it fails all or not though

Hoping my parts get here soon

Parts make it today?

[-=Jeff=-]

Nope looking like it will be Sat.

[-=Jeff=-]

I got the Stator but the Rebuild kit was sent to the wrong Post Office it seems, my guess it I will get it Monday :(

Which means this weekend will be beautiful

Oh well, I can finish replacing the front shock tower bushings tonight.. might pull the old Alt apart too

[-=Jeff=-]

Parts should be at home. Good I can get it tested this afternoon

[-=Jeff=-]

Built, tested, back together...

I also replaced the top shock bushings too, readjusted the coilovers so I it is not too high now

[XfireZ51]

Built, tested, back together...

I also replaced the top shock bushings too, readjusted the coilovers so I it is not too high now

Now if only the weather cooperated.

[-=Jeff=-]

Issue still exists will disconnect what I added this year and check. Wiring looks fine otherwise. Battery is next to be checked. It is 7 years old

[XfireZ51]

Issue still exists will disconnect what I added this year and check. Wiring looks fine otherwise. Battery is next to be checked. It is 7 years old

Occom's Razor, Jeff.

[-=Jeff=-]

Yeah I know.. Need to adjust rear shocks now too.. LOL

[-=Jeff=-]

One of the brushes shattered.. It was in at least 3 pieces.. Wonder if that was it.. I do have a rotor coming as well, may as well finish it right

[-=Jeff=-]

New Alt is in.. my custom build needs a regulator, it was taken out with the brush..

Voltages is sitting at 13.3 @ idle on the ECM datalogger.. DMM @ the Alt was showing a bit more if I recall correctly, but will verify again drops to 12.9 when I accelerate harder which makes me think the battery is getting near the end

I will feel better with a new battery although this one I have is from 10/2010. but have been told sitting is not the best thing for batteries either

[GOLDCYLON]

Built, tested, back together...

I also replaced the top shock bushings too, readjusted the coilovers so I it is not too high now


Well make a project out of it I aways say :cheers:

[GOLDCYLON]

New Alt is in.. my custom build needs a regulator, it was taken out with the brush..

Voltages is sitting at 13.3 @ idle on the ECM datalogger.. DMM @ the Alt was showing a bit more if I recall correctly, but will verify again drops to 12.9 when I accelerate harder which makes me think the battery is getting near the end

I will feel better with a new battery although this one I have is from 10/2010. but have been told sitting is not the best thing for batteries either

Awesome now get on that back shock adjustment :dancing

[-=Jeff=-]

More info

ECM Datalogger shows Battery voltage as 13.3-12.6

Voltage at Fuel pump never drops below 13.2 and is mostly 13.6

[-=Jeff=-]

Awesome now get on that back shock adjustment :dancing

After I confirm the Voltage crap.. LOL

driving it again later for a short bit..

[-=Jeff=-]

14.51 @ alternator. I think I am good, but will buy a battery for good measurr