may have a dead alternator

[LMHmedchem]

Hello,

I am in the process of flushing the cooling system after just getting the truck started after a long time idle. I charged the battery before starting up again but now I notice that the battery level is low. I put a DMM on the terminals with the truck running and I only get 10.8 volts. I was not in the truck revving to ~1000 rpm as I usually would be for that test, but that is still way too low.

I am wondering if there is anything I could have disturbed or disconnected to cause this, or do I just have a mostly dead alternator? How would I check? I have never noticed any issues at all with the alternator so it seems a bit odd that it should just suddenly not work. The battery is less than a year old and is a good battery. I had no issues when charging it. I don't want to get a new alternator unless I need one. I hate spending the money only to find that I have not fixed the problem.

If I do need an alternator, are there any suggestions as the the brand and model?

Here are some from part brands that I have used before and like,

Reman DENSO 2105313 130 Amp w/o Black Rear Cover, w/ 4-groove Serpentine Pulley ($104.79+ core)
Reman BOSCH AL7541X 130 Amps, May Not Include Pulley ($108.79 +core)
New ACDELCO 3351118 Gold 130 Amp, w/o Black Rear Cover, w/ 8S Pulley ($126.89)
New ACDELCO Gold 3351156 130 Amps, w/ Black Rear Cover, w/ 6S Pulley ($140.79)

The ACDelco reman is only $5 less than the new part so I wouldn't bother.

Do the listings that say w/o black rear cover mean that I need to save that part from my truck?
What is the difference between the 4, 6, and 8, grooved pulleys?

Thanks again for all the help.

LMHmedchem

 

[TechGuru]

Remember with RockAuto you have to pay the shipping of the core back so that eats into the core refund so personally I'd only buy NEW from RockAuto. If you want remanufactured go local.

That said, since there is no new Bosch for the V8 model I'd go with the new REMY from RockAuto.

More Information for REMY 92516

www.rockauto.com

 

[LMHmedchem]

Remember with RockAuto you have to pay the shipping of the core back so that eats into the core refund so personally I'd only buy NEW from RockAuto. If you want remanufactured go local.

Yes, this can be an issue, especially for a small core refund. Also, I see cases where the difference between new and remanufactured prices is small, there is no reason to not get a new part.

That said, since there is no new Bosch for the V8 model I'd go with the new REMY from RockAuto.

More Information for REMY 92516

www.rockauto.com

Thanks for the recommendation. I have never bought a Remy part so I would have overlooked that brand entirely. I also like Bosch. You like either Bosch or Remy over the ACDelco professional line?

Can anyone tell me where the alternator fuse is located? I can't seem to find it listed in the owners manual. Is it in the box between the battery and the firewall or is it elsewhere? Possibly it is named with an abbreviation?

LMHmedchem

 

[Mbrooks420]

It might have a fusible link inline with the alternator, and not a fuse in the box. If the link was blown you’d not get any voltage out of the alternator. If you’re handy you can rebuild the unit you have. You could probably source rebuild parts locally.

 

[LMHmedchem]

It might have a fusible link inline with the alternator, and not a fuse in the box. If the link was blown you’d not get any voltage out of the alternator. If you’re handy you can rebuild the unit you have. You could probably source rebuild parts locally.

I'm not sure that I am getting anything at all out of the alternator. My battery voltage was 12.7v with the truck off and it reads 11.7v at the battery with the truck running. I am trying to figure out how to read the voltage directly off of the alternator but I can't see any exposed metal on any of the leads.

I think that if I lift off this boot,

Alternator Wire Boot

I will see the red terminal and should be able to run a DMM from that to ground. Should that work or am I way off base? I am also not sure how to get the boot off without damaging anything. It seems to be on there pretty good. It seems odd to me that I would suddenly be getting nothing out of the alternator when I have had no previous signs of a problem. That is why I am checking connections and fuses and such. I have had allot of things apart lately and I want to make sure that I didn't miss something when I put it back together.

What parts would I need to rebuild? I would suspect that I would change out the voltage regulator but those are almost half the cost of a rebuilt alternator.

LMHmedchem

 

[Mbrooks420]

You should be able to read off the main terminal that goes to the battery to ground.

I’m not sure how you were trying to read amps in the first post, but I wouldn’t try that with a standard multimeter. Most won’t handle more than 10 amps.

 

[LMHmedchem]

I’m not sure how you were trying to read amps in the first post, but I wouldn’t try that with a standard multimeter. Most won’t handle more than 10 amps.

That was a typo, I meant volts. Thanks for pointing that out. I have fixed it in the original post.

You should be able to read off the main terminal that goes to the battery to ground.

I was able to get the boot back and read the voltage from the terminal on the alternator to ground. It reads 11.7v, which is the same as the value I was getting from reading at the battery. I guess it is still working some, just not enough. It's at least 2 volts low. I guess that means for sure that I need a new one. I have sprayed it up with PB and will try to get the old one off later.

LMHmedchem

 

[TechGuru]

Since the alternator is pretty easy to get to and remove on these vehicles just take it out and take it to AutoZone or OReilly's to be bench tested...

 

[TechGuru]

Yes, this can be an issue, especially for a small core refund. Also, I see cases where the difference between new and remanufactured prices is small, there is no reason to not get a new part.


Thanks for the recommendation. I have never bought a Remy part so I would have overlooked that brand entirely. I also like Bosch. You like either Bosch or Remy over the ACDelco professional line?

LMHmedchem

Actually I retract my statement. It seems REMY no longer offers a lifetime warranty!
REMY Warranty Information:
(Ordered After 10/1/2020) Remanufactured Units: 1-year / Unlimited Mileage; New Units: 2-years / Unlimited Mileage
(Ordered Before 10/1/2020) Limited Lifetime

So if you want a lifetime warranty I would just get a reman locally from AutoZone or OReilly.

$184.99 https://www.autozone.com/batteries-...r/p/duralast-alternator-dl3426-6-1/955059_0_0

$184.99 https://www.oreillyauto.com/detail/...-amp-alternator-remanufactured/ost0/r111738a/

Bosch Reman only has a 2 year warranty, only their new products have a lifetime.
ACDelco only has a 2 year on both reman and new.

 

[LMHmedchem]

Well I have already ordered the Remy. It should arrive on Tuesday. That will give me a little time to paint up the upper bracket before it goes back on. It's amazing how rusted the bolts were.

I couldn't find a new Bosch in the places I looked. I think that the new Remy for $139 with shipping is a pretty good deal, even if the warranty is only 2 years. The original part lasted almost 20 years so I expect this one should also do well.

I also ordered a new belt tensioner. I don't think that the tensioner was the issue, but it was a little hard to move and it needed a little coaxing to pop back up after I had the new belt on. I tried to push it even further up in case the low voltage was being caused by a loose belt, but it wouldn't go up any further and the voltage didn't change for all my pushing. At this point, I assume that most things on a 20 year old truck need to be replaced, or soon will, so when I have things apart and out I tend to replace more rather than less. For $30 I think it makes sense to do the tensioner now. The tensioner shipped from the same warehouse as other parts in my order, so the shipping didn't go up. If it had, maybe I would have waited. I also checked the idler pulleys and such while I was in there. The belt is new Motorcraft.

I thought about taking out the alternator to get tested as you suggest, but it's only putting out 11.7v from the red terminal on the alternator body (to ground), so I don't see how it can be working. Am I wrong about that? I will install the new tensioner before I pull the old alternator on the chance that it fixes the issue. I am not terribly hopeful.

Not to ask too many questions at once, but if I wanted to rebuild my original alternator myself, how would I go about that? What parts would I need?

LMHmedchem

 

[TechGuru]

I thought about taking out the alternator to get tested as you suggest, but it's only putting out 11.7v from the red terminal on the alternator body (to ground), so I don't see how it can be working. Am I wrong about that?

Because a voltage signal from the plug wire "turns on" / "activates" the alternator so getting it tested will let you know if the problem is the alternator or the vehicle wiring not turning it on.

 

[LMHmedchem]

I ended up taking my original alternator to 2 different AutoZone stores in my location. Both stores said that their bench testing equipment was not working. I figured I would eventually find out if my old alternator was working when I installed the new one, so I didn't go looking for any more places to get it tested.

I ended up getting,

REMY 92516 Remy Gold OE 130 Amp Alternator ($129.79 +ship)
GATES 38274 DriveAlign Premium OE Belt Tensioner ($27.79 +ship)
2x SKF 6203-2RS Ball Bearing ($12.94 shipping included)
5x Black Ultra Corrosion Resistant Coated Class 8.8 Steel Flanged Hex Bolt M6x1.0 25mm ($7.59 +ship)
2x Black Ultra Corrosion Resistant Coated Class 10.9 Steel Hex Bolt M8x1.25 60mm ($3.70 +ship)

I used the SKF 6203-2RS bearings to replace the bearings in both the idler pulleys. I just used a vice to press out the old bearings. I cleaned up the pulleys with a wire brush wheel and etched and repainted them with POR-15. They seem to be spinning nicely now. When I took them off, they sounded like they were filled with sand instead of grease. I played around with taking off the seal and re-greasing them, but I wasn't sure that the seal would go back on well enough. New SKF bearings were less than $6.50 each shipped, so that was even less than replacing them with really cheap SKP pulleys. I am not a fan of cheap bearings for something that has to turn the entire time the engine is running. As long as the bearings I got weren't counterfit, they should last at least as long as the original bearings.

The aluminum plated bolts I got to replace the 4 M6 bolts that hold the bracket in place were expensive at $1.50 each, but the old ones were so rusted that they crumbled as I removed them and were a pain to get out. I am now replacing the bolts for almost everything I repair. The bolts on the tensioner and idler pulleys were in really good shape so I reused them after a bit of cleanup.

At any rate, when I got it up and running again it now reads 14.6v at the alternator so it looks like everything is good. It would have been quite a bore to find out that the problem was something else after getting everything replaced.

I am still interested in rebuilding the old alternator so I would appreciate any information on how to go about that.

LMHmedchem

 

[TechGuru]

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