Electrical Smell - How to Trace?

[montenido]

Hi all,

Last weekend when I was motoring there was a belt squeal for a short time with an accompanying smell of overloaded electrical. I shut down the engine and opened the engine room up. No visible smoke, no signs of any trouble, but the alternator belt was hot to the touch. I had been motoring all day up until them with no problems at all. I fired the engine back up, and when nothing happened out of the ordinary, I motored home for another 3 hours with no further issues (no wind at all).

Back in the slip I took a closer look and detected a fair amount of belt dust on the alternator and surrounding parts. So I cleaned off the dust and re-shimmed the alternator to make it run more true. Is there a chance that the alternator inhaled too much belt dust, causing the electrical smell?

Today I took the boat out with no problems until I re-started the motor to come into the marina. Same belt squeal with accompanying electrical smell. Checked things and again found no obvious problems, so I restarted the motor and ran it another 30 minutes or so with no smell or problems.

I have one of the small frame Balmar alternators with a smart regulator mounted on a Perkins 4-154 on my boat. How might I begin trouble shooting the electrical smell? I think it might be tied to the alternator somehow.

All suggestions are welcome.

Cheers, Bill

[sabray]

What was the condition if the charge demand on the alternator? Is the belt glazed? is it tensioned properly? Check the terminations on the alternator at both ends. Look at the fuses that may be in the engine room. What was on drawing at the time?

[Wotname]

Belt squeal indicates slipping belt. Fix that first. It stops slipping after it overheats and becomes slightly sticky.

It may be slipping due to:
being loose;
glazed;
wear;
overloaded.

Replace belt and if it still slips when correctly tensioned, it is probably overloaded. At a pinch, you might try a belt gripping compound if it isn't highly overloaded.

Are you sure it isn't an overheated belt that you can smell?

[colemj]

Belt burning/dusting/gazing smells just like electrical insulation burning, so I think that is all you are smelling.

What belts are you using? If you put a higher output alternator on, most likely your old standard belts will not cut the mustard anymore.

Gates makes very good belts for this application. Try to get their green stripe line, but that only starts at a particular size, so don't know if it will fit your setup. If not, their XL series are very good also.

You need to determine if the belt is being abraded and sinking lower in the pulley, or if the alternator is slipping on its mounts. Sounds like abrasion, since you have a lot of belt dust.

Try sanding the (possibly) rough edges of all the pulleys and recheck the alignment with a dowel.

Mark

[montenido]

Thanks for the quick replies everybody. I do think it is the belt that I was smelling, but the similarity to electrical overload smell made me very nervous. I have had the boat for one year and this belt was on it when I bought her. I re-aligned the alternator a while back due to the dust, but when I looked at it this week it was still off by over 1/4". It is shimmed pretty close to straight now, so I will put on a new high quality belt and see if the smell comes back.

Thanks again, Bill