Shop Discount Alternators

Pardon my jumping in, here. It really sounds that you've got a defective alternator. It happens. As Tom suggested, you really should have it retested. There are different qualities of rebuilt units. Remember, you get what you pay for. We have switched to CarQuest reman. alternators and starters. They also have new ones available in increasing applications, but they can be considerably more money. And, it's not uncommon to get a whole lot number of bad units. Just because some el-cheapo parts stores have a lifetime warranty, that doesn't insure quality. Just that they'll replace it. GM alternators are about the easiest to open and replace the diode trio or regulator, but if it's still under warranty, you don't want to do that. Of course, make sure that all of your connections are clean and tight. And, that the battery is capable of accepting the charge. Again, as Tom mentioned, a defective battery can take out an alternator. And, discharging and re-charging the battery is really hard on it.

Back to top you said this alternator was replaced just last month. Take it back as if you open it you'll void any warranty.

At home "bench" testing would be on the car as you would need to spin the thing. The parts stores have that machine and it either works when prompted or not - they (usually) won't be able to state just why just a go or no go.

I just searched around for simple ohms tests or what to ground for forcing it and nothing was good enough for me to post so I suggest taking it for testing.

All the parts are available but the trouble of late is the whole unit is available for about twice the price of each replaceable part one by one so not very cost effective.

Ok: Regulator and diodes are inside on any recent GMs that I've run across. If wiring looks perfect and YOU own this alt, you could open it and look for something burned. I don't know on this one what ohms should test what testing from what to what.

Yes - the red wire stays hot and should on this. The two wire connector should be for the gauge/warning light and with ign on will enable it to charge. There is a way to add ground or power to one of those to force output to max and I just don't know which so I'll suggest don't!

Perhaps Loren or another knows which you do what with on this - I don't and didn't just find anything credible to pass on for this Delco or possible Delphi alternator??

Again - less than a month - take it back,

T

thanks a million tom for replaying so fast, as a matter of fact my alternator had only three days warranty as it is used.
you mentioned the two wire connector, i remember that the battery sign inside tha dash board does not come on. i did see it long time age but now i don't see it on. any clue
as i also said, if i charge the battery out side the car and return back, the alternator gives me 14v. which sounds it charging, then 2-3 days the battary dies and the alternator does not charge it if i jump start it.

thanks again tom, and i will tell if the problem is solved.

3 Day warr! I'm shocked! Used is used but usually for the lower price they'll still give at least 30 day on anything.

Some things don't add up. Charge the battery (new or is it used too?) while it's in the car. Start it and read the voltage with the engine running - what is it then without a charger on it?

Does this have a volt gauge or just a batt warning light icon on dash or both. Generally when you turn key to "run" but not start the car the bulbs will light as a bulb check for which are working and go out when running. If there's only a battery warning light some much older GMs would fail to charge because of that but never heard of that since the 60s!

Note: If for any reason the battery is run down too low to start engine then just jumped the alternator would be overworked if it worked trying to charge battery back up and that alone can kill an alternator with high heat.

NoteII: While running you should see over 13v about all the time and if less there's a problem as well as over 15v a problem. You can put a volt meter if you wish hooked up thru power port/cig lighter if you don't have or trust a volt gauge on instruments.

You said it would last three days if charged off car! How many miles or how much run time is that? I'd like to see what the volts read with it running and then with it running with headlights on and fan blower on high with a raised idle. Report that and I'll have a clue on what next would be best.

One more - How much did this used alternator cost? Diodes are about $40 bucks alone and whole unit rebuilt ~$120 or so,

T

Dear Tom
Battery is new... voltage on battery with charger on it 14v, charger away 9-10v
the warning light on dash stays on while engine is running even when charger on the battery
when battery charged off car to full it lasts about 30 miles with lights on and AC on
i checked the voltage between the wire connector while car is on on position and while it's running and voltage was zero and resistance was 36 ohms.
last, i bought that alternator for about $95 not from usa.
thanks all

Back:

If this new battery shows as low as 9v when charged! No need to report what the reading is when the carger is on it as you are just reading the charger - we need to know what the battery is by itself. A bad battery can easily kill an alternator.

Make sure you are charging posts to the battery and not just on it's cables as they might not be making a great connection. Take readings from the battery itself and not the clamps as well.

Side note: You can take a good brand new battery with no help from a vehicle's alternator to maintain it and it will run for a period of time till it's charge runs too low to run the vehicle. It isn't a cell phone battery - taking the typical lead acid car battery down destroys them in just a few total run downs.

Side note II: The common battery is made to be at 100% almost all the time. When you draw from it to start the vehicle it takes away some percent - like 5% of it total available charge if the vehicle starts right up - then the alternator will quickly restore the battery to 100% and the alternator is running the electrical items while running.

If you drop a battery to 50% with multiple failed starts or leaving something on by mistake the alternator will blow it's brains out trying to get it back to 100% and usually will. When you get down to 10-20% and they can get dropped to zero you are killing the battery and the alternator will constantly overwork, get so hot it ruins it.

The two need each other and either can kill the other so when you get caught with one bad make haste to be sure both are restored to good or it's just ping pong of repeated failures,

T

hashhead; 12.45V is okay. A fully charged 12V battery will have 13.2V. But, at this point, all you are doing is showing surface voltage. If the battery holds a 200A load for 15 seconds and stays above 9.6V, the battery is okay. Once the engine is started, charging voltage should be between 13.6V and 14.6V. You'll need an amp guage to check for amperage output as well.

does anyone know if the fuel injection control module and the alternator have anything to do with each other ?

found something on another forum about my abs system i removed the fuse for the abs system and everything works great now charging system is good alt doesnt get hot every thing seems to be good i will have the abs system checked out but atleast i can use the truck for now . Thanks for everyones help and your time on my problem i will be sure to return the favor when i can !!!!!!!

That's interesting. Which fuse did you pull? Was it the 60 amp? If so, something in the ABS system is using a lot of current and overworking the alternator.

Has the ABS light been on before removing the fuse?

We'll keep this thread open, so let us know what they find out about the ABS system.

2004 - you should be on your third battery!

Tom

Is this vehicle used for snowplowing or does it have any aftermarket accessories that use a lot of current?

I do not have a snowplow or any aftermarket acc. on my truck it just started getting hot and shutting of so i replaced the alternator cleaned all connection and checked all plugs on the engine that i could find but after minutes of running the alt gets very very hot and shuts off.

Have you checked the cable from the alternator to ensure it isn't shorting out somewhere? Thats a tight engine bay in there and things do rub.

thanks but i did follow the cables from alt to batteries no signs of broken wires or shorts all wires test good

Wonder if you could get your hands on an amp clamp and see how much current it is putting out.

Double check the basics.....Make sure all the connections are clean & tight......Look for missing or broken body to engine ground straps....I won't go into the whole story but bad grounds can cause bearings, mounts & other things to fail prematurely.....Current gets home any way it can and it doesn't care what it goes thru to get there......just that it can go thru it....

I can't say for sure on yours but on some GMs the feed for the alt runs off the starter solenoid.....I've had some weird charging system problems on GMs that were traced back to a loose nut on the starter solenoid.......

At the rate you are going thru alternators.....It might not be a bad idea to let the electrial shop take a look at it.....

Comments: Battery in trunk! OK - Some others are under a back seat or in closed quarters do need to attach to vent outside vehicle and the vent hoses should be right there waiting. If hard to find doesn't surprise me. WE ARE TALKING HYDROGEN GASSES that can not be allowed to accumulate in a closed area - disasters happen over that.

Eating up alternators. Tons of cheap junk that isn't really rebuilt but more like cleaned up and brushes perhaps. If a battery is weak or low it does really strain an alternator. Belt must be known properly tensioned.

Other: I don't know of a good bargain battery especially lately. This is not a place to save a buck. I'm not even sure what brand or place to suggest anymore as things change so fast as to who really makes what and just gets a name slapped on them. There's also a factor with how they are handled along the way. They don't do being dropped and bounced around well nor being tipped over. Gel cell ones made for wild extremes can handle that but cost a real fortune.

Other issues are they are not in full state of charge when first made new. Some will charge them but near know most don't. Batteries don't like being at part charge or low and worse they can sit unsold for many months but are marked when they were made new. You can end up with a year old new battery but the aging starts when it was made.

It is a problem and you can end up playing ping-pong with batteries and alternators each dependent on the other being good. Unsure of this popular free battery testing too. Better than not doing anythng but I don't think it is perfect to know if one is really good or not?? - T

No aftermarket sound system. Regular standard GM Delco radio that came with the car.

I thank you for the idea to check the battery. The battery was replaced under warranty one month ago. It went bad after about 35 months. Now I have a new battery. I replaced the alternator a week ago because a new battery did not fix the problem. New battery new alternator. The battery light on the dashboard still intermittently occasionally flashes to indicate the alternator is not charging. I'm wondering what are the implications for battery performance if it needs to be vented and I got a regular old battery from Pep Boys? After you mentioned checking the battery I did some research and found out I need a vented battery for the Ion because it is housed in the trunk. I will also check the amps rating on the battery they gave me. Three years ago I walked into Pep Boys and asked for a battery. They looked it up in their computer system and gave me one. I'm wondering if perhaps they did not give me the wrong battery and that is the source of all of these problems with the alternator and battery going bad? Either this venting feature not being present on the battery I bought kills batteries or they gave me a battery that was too small for the job?

Several people have told me that the shop is probably using cheap bottom of the line alternators that go bad.


That's what I would guess. It's pretty hard to find any quality these days and competition pushes them into the cheapest thing they can find.

Would help if we knew what kind of alternator you have.

You won't save a thing - forget that idea completely. Did a ton of pretty large yacht misc stuff over many years.

OK - just because the engine may not need electricity for anything to run there are a zillion things still using some power all over a typical yacht unless it's an empty shell.

Alternator is almost just a nothing pulley for power loss if not powering something anyway. Even the best deep cycle battery(s) w starting amps enough for a diesel engine doesn't like going low just tolerates it lots better and when you do enable it it would just make up drag to recharge them later.

Do you really want to risk it not starting because you let it get too low?

Last yacht I did a lot on had power for water for 3 sinks, ice maker, six bilge pumps, TV, radios, gauge lighting and 100 more things I can't think of right now and guess you could do without blowers for heat and A/C if equipped underway.

Even sail boats of size need power for pumps. Yes - most charge battery(s) slowly with just a little wind generator usually at the top of the mast.

The other problem is when you ask an alternator to charge hard with low battery(s) is you are really stressing it out and can kill it. Much bigger bucks than automotive as it must be designed not to make sparks.

In short - you save nothing and risk a lot. Last one I deal with a lot had SIX deep cycle batteries and could choose 3 at a time, all or either set such that a failure still left you with at least starting power if one set failed in any way.

Enough crap is always going wrong in a real yacht all the time and you want to mess it up even worse?

T