HOT Alternator

[Tom Glennon]

Here's a new one... while working on the plumbing of the hot water tank, to make sure all was nice and drip-free, I began to notice a very definate smell of "electrical cooking".  At first I thought perhaps the bilge pump/float, or perhaps the fresh water pump, but they were all fine.

I then moved into the head and opened the access door there, and definately detected a strong odor.
I immediately removed the access to the engine, and low-and-behold, discovered the alternator was HOT. Very HOT.... I immediately turned off the master DC switch. 
Earlier in the day I ran the engine for the first time after winter lay-up, and all apeared to function properly.

I later removed the alternator, when it was cool enough to handle.
I will be bringing it to my alternator shop for diagnosis... but just wondered if anyone else ever had a similar problem? 

[Randy and Mary Davison]

Cooked a bearing once with a slipping belt but it sounds like yours was hot with the eniine stopped?

[Stu Jackson]

This is a week of unique input, Tom.  I haven't heard of this before either.  The issue ahead of you is to find out why by tracing your wiring, or examining the wiring design itself if you already know how it's hooked up.  Was your ignition key on?  Battery switch?  OEM alternator?  Upgraded?  Age? External regulation?

Seems doubtful given the work you were doing, but the path of juice to the alternator usually runs through the C post of the 1-2-B switch unless you've changed the wiring as I described in many posts and the Nov. 2006 Mainsheet article.  We'll need a little bit more input from you to help, since it may NOT be an alternator (only) problem.

[Tom Glennon]

My first thought was the ignition switch, but the fuel pump was not clicking, so I am assuming (oops) that something is wrong internally with the alternator.

The key was switched off.  As I said, I did run the engine for about 5 minutes earlier, and all seeme ok... no squealing of pully and the alt was putting out charge, as the volt meter was reading, although slight, as both batteries were fully charged.

I should know something tomorrow regarding the condition of the alternator, and I will report back.
The alternator is a replacement for the original, replaced last August... due to a cracked tensioning bracket which caused the alternator to "wiggle" and make the mounting hole through which the long bolt passes, elongate.

[steve stoneback]

Tom,
Do you still have the old alternator that you took off last August?  If you do, and it works, you could possibly put the guts from that one into the one that may be fried but has a good casing.
Steve

[Tom Glennon]

The company replaced the alternator without much explainaition other than it was "messed up" inside.
I know I had the wires on correctly.... so I would advise you all to jsut keep it in the back of your minds, that sometimes these things could be a real cause for concern!

[Stu Jackson]

Tom

That's great that they replaced the alternator.

Was there any reason whatsoever offered by them as to HOW it could do that with the ignition switch in the OFF position?

Only thing I can think of is that it's got a positive output to the battery bank and is grounded, so that something inside fried and closed the circuit, once the 1-2-B switch was turned on.