Alternator

[Jetpilot1]

Matt and Nascar

Matt;

Nice post, shows the difference in alternators well.

Nascar: The 6G alternator is more robust overall putting out more amps at idle and top end, the big improvement though is to get the heavy duty rectifier (internal) option. When the alternators fail, it is almost always is just the puny little rectifiers in the alternator that are the problem. So we spend lots of money on a new alternator but all that really is broken is the rectifier. The ugraded 6G can be ordered with the heavy rectifier - thats the key for longevity. A lot of the other aftermarket (or OE) alternators just use the OE rectifiers, and the diesel with its charging requirements will make short work of them. The glow plugs for example are a 180 amp draw - which is why the computer shuts off the alternator for a few minutes until they shut off. But then there is a heavy charging load on the alternator to recharge the batteries. So you can see a lot of short trips in a row are very hard on both the batteries and the alternator, never mind the stereo or heated seats!!

I don't think the pulley is any smaller, but any difference is automatically taken up with the belt tensioner.

 

[Matt24601]

I pulled the batteries out and had them tested individually, both came back fine. While running, the charging system is putting out 12.22 volts which is not enough. I am going to pull the alternator tomorrow morning and take it up to Autozone to test. Hopefully it is the alternator and I can just send it back and get a replacement unit, but I have a hard time believing that two alternators one at least being a very reputable unit can both fail within 6 weeks time. We'll see.

 

[BIG JOE]

I pulled the batteries out and had them tested individually, both came back fine. While running, the charging system is putting out 12.22 volts which is not enough. I am going to pull the alternator tomorrow morning and take it up to Autozone to test. Hopefully it is the alternator and I can just send it back and get a replacement unit, but I have a hard time believing that two alternators one at least being a very reputable unit can both fail within 6 weeks time. We'll see.

Hmmm.

Did you get the running, 12.22v reading from the Batterys.... or from the Alternator ?

 

[Matt24601]

I got the voltage from a cigarette lighter plug-in tester I bought the other day. I may not be 100% on the tester, but it confirms what the Autozone tester said as well. I took the alternator into Autozone today and it tested out fine. That means the batteries both tested fine and the alternator tested fine. This brings me to the latest development:

when I disconnected the alternator I discovered this:



The boot and casing have been melted. Here are some more shots:




In case you are wondering, you can scroll down to one of my previous posts in this thread to see what it looked like before it got cooked. Now the question becomes : where do I go from here?

1. Should I assume there is a short somewhere? Anybody know where that main cable coming out of the alternator leads to? I'd like to check the length of it if I could to check.

2. Any fuses that need to be checked?

Something to consider is that this problem is unique to the install of this new alternator. I replaced an old remanufactured unit with this HD model. I am going to get in touch with Alternatorparts.com tomorrow and see if they have had anything like this happen before.

Thanks for any input.

 

[BIG JOE]

At this point, getting ahold of AlternatorParts would be the next, and right thing to do.

I'll sure be interested to hear what they have to say.. TOO !

Being the Alt. checked Good... maybe the lug/post connection was able to arc to the Alt body.... just a bit ?

FWIW ? I always make sure the crimped side of the ring connector is facing away from the Alt. body.. then bend it a away from the body.. just a bit.. after tightening it

Joe

 

[Jetpilot1]

Like Big Joe said, it looks like the terminal was able to short to the alternator case.

 

[Desertstroker]

On another post there was a link for a high output alternator and it went to a listing on Ebay for a DB electronics I think. If you page down at the end of the sellers listing it said that for "safety reasons" they recommend a kit they sell that had 4 gauge wire and an inline fuse block. They recommend this so the alternator will charge at the higher amperage I guess. I don't know if this is neccessary, just thought I would mention it.

 

[Matt24601]

I'll check with alternatorparts.com tomorrow. I think the forum diagnosis sounds pretty much spot on. Thanks Desertstroker, I found what you were talking about with the install kit. The only thing I noticed was that in their pictures, the back of the alternator they are using is covered with a plastic housing. The terminal wouldn't be able to make contact with the metal alternator housing in that example, but with my alternator, the entire thing is metal and I think I'm going to have to figure some way to keep the terminal from touching.

Any ideas on where to get a replacement boot for the end of my fried cable, or am I going to have to "engineer" one myself?

 

[Matt24601]

I ended up putting two large rubber washers behind the terminal lug on the back of the alternator. This will hopefully ensure that it never grounds itself again.

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I cut off the fried boot on my wire and put a new copper lead on it. A few layers of heatshrink tubing over the crimp and I bolted everything back up. I started up the engine and my voltage meter is now reading at 14 volts charging.

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Hopefully this is the end of the problem. Anybody know why this setup may fail in the future? Anything to watch out for?