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Burning smell, lots of smoke at times, none at other times.


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crashedhdd
New User

Jul 8, 2014, 10:25 AM

Post #1 of 4 (1030 views)
Burning smell, lots of smoke at times, none at other times. Sign In

I asked this in another thread hoping that not only I could receive some help but also the person who started that thread could benefit as well. Alas I was told to start a new thread so here goes..

I have a 99 nissan altima. Lately I've been seeing smoke coming from under the hood and it smells like electrical wires burning (maybe the shelac on the alternator windings). It only happens while at idle and on particularly hot days. I opened the hood and I can see smoke coming directly out of the alternator (where the windings are visible). Anyone know what causes this? I don't hear any noises that would suggest the bearings are bad or dragging. The battery is charging fine (~14v measured) and starting the engine is ok too. Car runs nice otherwise. I'll pull out the alternator and replace it but I'd like to know the cause. Thanks for any input.Wink


crashedhdd
New User

Jul 8, 2014, 11:21 AM

Post #2 of 4 (1022 views)
Re: Burning smell, lots of smoke at times, none at other times. Sign In

Well, I checked into this problem a little more and found that at idle the output slowly drops (about .1v every 10 seconds) and when it reaches about 12.5v the alternator begins emitting a burning odor. When the output reaches about 12v smoke appears from the alternator. If I raise the idle about 100 rpm then output remains steady at 14.02v and the smoke goes away.

The failure appears to be in the windings of the alternator and not the regulator since high idle locks at 14v. For now I'll raise the rpm a little (snug up the accelerator cable so it's like I have my foot on the pedal) until I get a replacement. Adjusting anywhere else may cause the idle control system to compensate which is what I want to avoid.

I hope this helps others with smoking alternator problems.

Cheers!


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jul 8, 2014, 12:02 PM

Post #3 of 4 (1017 views)
Re: Burning smell, lots of smoke at times, none at other times. Sign In

When you do your alternator have your battery tested. If you have a battery that is weak or shorting out internally, it could cause the alternator to go full tilt. Going full tilt too long can cause the alternator to overheat.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jul 8, 2014, 12:03 PM)


crashedhdd
New User

Jul 8, 2014, 12:27 PM

Post #4 of 4 (1009 views)
Re: Burning smell, lots of smoke at times, none at other times. Sign In

yep, I hear ya. The battery should be ok though. Starts up fine with no indications of weakness. I checked for a voltage drop across the terminals too with none to be found. The only thing with raising the idle a little (about 100 rpm) is that while in gear the car wants to go and I'm holding it still with the brakes. So to prevent tranny fluid from heating up and causing excessive wear I'll put it in neutral when resting at a light or when stuck in traffic. I'll get a new alternator within a week. I think this is good enough to prevent an alternator fire while waiting on my paycheck. Also, I think I'll install an aftermarket volt meter inside the cabin so that this type of problem can be more readily ovserved in the future.

Thanks for the great advice!






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