not charging well with new alternator

[big_truxx]

justreplaced the alt in my 6.2 burb and now it doesnt seem to wanna charge well. if running at idle with glow plugs off it will charge up to normal on gauge but if put wipers lights and blower on it will go way down almost to red. tried swaping ion batteries that were better and still same deal. what gives? the only thing i noticed that was odd was a bolt on the back of the alt that has no purpose. is that a new design where they have a ground strap going there as the normal bracketry isnt a good ground or something?

 

[dremu]

justreplaced the alt in my 6.2 burb and now it doesnt seem to wanna charge well. if running at idle with glow plugs off it will charge up to normal on gauge but if put wipers lights and blower on it will go way down almost to red. tried swaping ion batteries that were better and still same deal. what gives? the only thing i noticed that was odd was a bolt on the back of the alt that has no purpose. is that a new design where they have a ground strap going there as the normal bracketry isnt a good ground or something?

Where'd you get the alternator?

Most of the military CUCV's have a second alternator which is floating ground, so if yours came off such a truck, yup, that's your culprit.

-- A

 

[big_truxx]

Where'd you get the alternator?

Most of the military CUCV's have a second alternator which is floating ground, so if yours came off such a truck, yup, that's your culprit.

-- A

from advanced auto and its sposed to be for an 89 diesle burb lol they dont have anything in the comps about the cucv's i dont think

 

[big_truxx]

anyone got any ideas?

 

[Dallin]

You haven't given us much to go on, and I'm not sure what you mean by "charge up to normal."

Measure the voltage at the battery with the truck off. It should read about 12.6V. Measure it again with the truck running it should be about 14V. With the truck running turn on the headlights, AC, and windshield wipers. Measure the voltage again. If it dropped a lot from the second reading then your alternator may not be putting out as much current as it should be.

 

[big_truxx]

ok latest info...

just put an ac delco alternator in tonight. and now i am noticing when i put a blinker on the volt meter in the dash "ticks" with the blinker... i am thinking this is bad. also the volt meter reads at about 10.5v when i am driving have to use lights this time of year lol so... i am thinking i have a short or something wrong with electrical somewhere. anyone shed some light on this for me?

further info if helpful is i have an 89 burb 6.2 400 trans a/c dual batteries. not sure any other info or what will be helpful in helping me figure this out.

thanks
chris

 

[nstarry]

block to body ground

 

[big_truxx]

block to body ground

thanks i will go check that or when it is light out and warmer and hopefully not raining lol

 

[Big89Burban]

Did you know what amperage your original alt. was? Just asking cause sounds like there giving you alt. that are weak. What is the orginal, and what is the one you have now?

 

[big_truxx]

Did you know what amperage your original alt. was? Just asking cause sounds like there giving you alt. that are weak. What is the orginal, and what is the one you have now?

i had kinda thought of that but nmot sure. whatever came with it when i bought it was what i replaced and new one i do not know either. the cheapo i took back to swap in on the ac delco was 78 amp one iirc. the ac delco i am not sure.

i have looked at (just now) my blaock to cab, starter, and they seem ok

i am wondering about the volt meter's "ticking" now that i noticed it when i use my blinkers....

we will see in a day or so if they batteries charge up or are dead... i am not going to charge the batteries or swap them see how it does on its own for a bit. i am perplexed at this as i am not good with electrical stuff

 

[Big89Burban]

If you have a voltmeter check what the alt. is putting out right at the rear terminal with those normal loads on (headlights & highbeams). If the voltage is normal (at least above 13.0) then check the resistance of the chargeback wire to make sure its not the alt. thats bad but some other component like a corroded wire/terminal etc..

You could do that one of two ways. You could unplug the battery and use and ohmmeter on the charge back wire but it would be best to do a voltage drop of the wire. All you have to do is put the positive lead of the voltmeter on the rear terminal of the alt., then put the negative on each positive bat. terminal. The reading will be the amount of voltage your losing through the wire. If its excessive (they say about .1 volt for each connection the wire has) then that might be the prob.

Hope that helps

Edit: I guess you could just check the voltage at each positive bat. terminal to see if voltage is dropping too. I get ahead of myself sometimes

 

[big_truxx]

well i spose i should try to get a tester thingy (voltmeter whatever they are called) sometime soon.

also to clarify now i thought of it i was refferering to the voltmeter in the dash as a gauge. i do not own a voltmeter to test things with yet

 

[diesel4me]

Check this..

See if you have 12v at both wires on the two prong plug at the altenator,with the motor running.(a test light will work)-.(should be a red wire and a tan or white wire)..if only the red wire has power,your not getting any juice to "excite" the feild coils in the altenator,and it will not charge,no matter how many altenators you install..

You should feel a magnetic "pull" if you put a screwdriver near the rear bearing of the altenator if its charging (be careful not to touch the big red wire on the stud to ground )..that is a "rough" test to see if its charging at all..Get a voltmeter to see exactly how many volts its putting out..GM stock voltmeters are often not very accurate..it might just be making you THINK its not charging ,when it actually IS..! good luck..

 

[big_truxx]

GM stock voltmeters are often not very accurate..it might just be making you THINK its not charging ,when it actually IS..! good luck..

I was also thinking about this too. i mean my burb could have 270k or 370k.... it says 70k on odometer and has a mr goodwrench motor in it... it is in good shape but i have no idea of how many miles are on it lol so i was very much hoping that the gauge had kinda gone bad after the years. but with the elcheapo alt i just replaced, the batteries were draining. but those were said to have problems anyway. i guess time will tell in a couple days if i am still starting the truck or if the batteries are dead. spose i could order a new gauge and see if it works. lol

 

[3 on the tree]

You can pick up cheap multimeter for less than 20 bucks easily. Once you own one, it will get alot of use. They eliminate a bunch of head scratching when dealing with elec stuff.

 

[jekquistk5]

A voltmeter/multimeter doesn't test amps. You need to test amps. A multimeter just tests voltage, resistance(ohms) and continuity. Now you can get one that does more but you will be shelling out quite a bit of dough for a nice Fluke. But if you test with a voltmeter and its putting out 12v or less its bad. I believe it should be 13.8V ish.

 

[unclematty]

I just read through all that and thought, Wow no one even mentioned what amperage you should be reading, so here is the low down.
1.you need to read at least 14.0 volts and around 50 amps or the thing won't charge the battery.
2.for your setup, I would suggest a 140 amp alternator, for all that stuff your running, you should run atleast that.
3. your gunna have to get good cables and a high cold cranking amp battery, my best guess would be atleast 800 cca.
4 the alternator wiring (I'm not sure of the color) but one should have battery power to it constant a direct lead to the battery, and a little heavier gauge then the others, another with power constant, and another with power, key on only.
5. with these things in place theres no reason it shouldn't be charging.

 

[big_truxx]

talked to a bud's dad today and he suggested a brand new alternator from summit one wire style sounds like a good option at this point shoulda thought of that sooner i guess i will have to try and get some time tomorrow to diagnose the prob more/ see if i can correct it.

thanks for helping everyone!! I now have a start (and a multimeter) in fixing it.

 

[Big89Burban]

I just read through all that and thought, Wow no one even mentioned what amperage you should be reading, so here is the low down.

Did you know what amperage your original alt. was? Just asking cause sounds like there giving you alt. that are weak. What is the orginal, and what is the one you have now?

The main reason that no one reccomends trying to check amperage is that NO voltmeter can check charging amperage. Most only go to 10amps. So the only way you can verify the amperage potential of the alt. is to use a VAT-40. Now seeing as he didnt even have a $20 voltmeter "thing" (as he put it). I dont see the chances being high that he has a 400-500 dollar VAT-40.




Edit: Just those few checks mentioned above shouldnt even take 10min. You wont even have to wait days to throw another part at it. Just do those things mentioned above and give the results and you should be well on your way to solving it.

 

[unclematty]

The main reason that no one reccomends trying to check amperage is that NO voltmeter can check charging amperage. Most only go to 10amps. So the only way you can verify the amperage potential of the alt. is to use a VAT-40. Now seeing as he didnt even have a $20 voltmeter "thing" (as he put it). I dont see the chances being high that he has a 400-500 dollar VAT-40.




Edit: Just those few checks mentioned above shouldnt even take 10min. You wont even have to wait days to throw another part at it. Just do those things mentioned above and give the results and you should be well on your way to solving it.

Sorry man! I had already posted when I read through what you had posted I get used to thinking just cuz I have an ammeter, that everyone else does too, sorry, Snappy on makes the one I have it attaches to my DVOM (voltmeter) and is accurate to .001 miliamps. It's about 200 bucks ontop of the 5 bills for the DVOM. But I live and die by it for electrical work.


Oh and one more thing big89burban, wheres your membership??? (no criticizing the locals till your a member)

Back on topic let us all know when you get this thing fixed!