Alternator question.. Please help
 

My denso alternator has no output. At 220,000 miles it's probably shot. I took the truck down to an alternator shop, where they verified no output.

So the shop owner says $180 for a rebuilt 120 amp denso. I asked him about a 136 amp denso since thats what is on my build sheet. He says the 136 amp ones wont fit.

I brought the truck home and removed the bad alternator and took it to the shop for repair or core exchange. Now I am starting to wonder if I am getting screwed, something just dont sound right. What denso's fit my truck in my sig.

If I wanted a smaller 120 amp alt, I could of went to auto zone for $130.

What do you guys think? Thanks.

Having no output does not mean its the Alt. , it just means that for a number of reasons , its not charging .
The regulator is in the computer , it could be the Alt. , wiring , regulator .
If you already have it out , have it bench tested , sometimes they can be weak , warn brushes .
Larry B's is where I got mine [ I will look for the link ] I have been in the auto repair bis for a few decades , and do not like a lot of rebuilding , especially the cheaper ones , they will replace only whats wrong , so a % of used parts on the rebuilt Alt.
Not just starting issues .

http://www.fostertruck.com/dodge/default.htm

When I took the alternator to the shop(for core exchange) they put it on the bench for the spin test. It had no output, could be as simple as the diode plate but...

If this shop has worked on Denso alternators they should tell you up front that brushes and slip ring are the weak area of an otherwise bomb proof unit.
I replaced my brush pack for under $10 and turned the slip ring true.

That gives you the choice to do both , when I had some extra money laying around I bought the new from Larry B's , get the rebuild kit like the other John mentioned , and you can put in just what is bad , after that the bearings are easy to get , if needed .

John , are following me around ?

Kinda appears that for the past couple days. Just had time so hitting the threads by title that I have knowledge.

Bearings are possible, but lower on the list. These are very stout units outside of that crappy brush & slip ring design. About an hour job to replace the brush pack & turn the ring. Shop where I get my parts said they replace slip rings instead of turning.

it's probably the brushes they are real easy to change

Thanks guys.. I went back to the alternator shop and he showed me the rebuilt one. It is a 136 amp denso at least that is what the guy told me. For all I know it could be a 120 amp denso, how could I tell the difference anyway. The old alt had a bad diode plate and he showed me the slip rings or comutator and the copper was wore almost through.
So out the door I go with the rebuilt alt and $180 less, but possibly next time I need to do an alternator I might try and do it myself and save some $$.

Thanks again..

For less than you spendt, I upgraded to a 160 amp new. Yes it appears to be a Denso knockoff, but looks identical to orginal. Also ran another wire from alt output to right battery to carry extra amps. Works great. Isn't the internet great for finding deals and info.