Smoke and burning rubber smell

[gatorcruz]

had a new alternator belt installed recently. took it out for a test drive this evening for first time since new belt. she ran good... got her up to 70 on the highway for several miles. after i got off i noticed that the speedometer was messed up... and the voltmeter was low... then smelled burning rubber and had some smoke coming up from engine compartment. started to pull off, speedometer was pegged and bounced around some.

opened the doghouse expecting to find the belt had broken or something.... but could not find any visible problems. after about 20 minutes of inspecting everything, i started it up and drove her home slowing. problem did not reoccur.

any ideas... was it just the belt slipping or breaking in...???

1996 Chevy 7.4 ltr

[Jackm]

In all probability, it was most likely the new belt starting to burn up (too much of a coincidence). In any case, I would replace the belt immediately since it was most likely compromised. However, I would also inspect each component to see if you can identify the cause. Best of luck.

Jack

[wa8yxm]

I would also check the belt tension (or if a serpentine belt the idler pulley tension) and the alternator and everything else it wraps around to make sure you do not have a seized bearing.

Sure looks like it either a tension or seizuer issue

True story: I once had a Ford Granada.. Dang thing ran fine all day, started fine, but drive it at night and you got no start in the AM. Turns out the alternator belt specified (A V-Belt) was the wring size, The right length but too narrow, for the pullies on the engine.. I measured, and purchased a wider belt, and... Instant worked great.

[gatorcruz]

OK... I've been able to reproduce the problem twice now... letting it idle in the driveway with the AC running so there is a draw on the system.

After about 20 minutes the Volts drop all the way off and the Speedometer pegs all the way to the right... there is a slight smell of burning (rubber i think). I quickly turn it off shortly after it happens so not as bad a smell and no smoke.

The second time I was under the rig and watching the Generator/Alternator. I thought it may be ceasing up but I did not notice that...

Any ideas? I can't find any of these symptoms in my manual.

Thanks.

JC

[J Walker]

Your alternator may be seizing and causing the belt to smoke. It would also produce the voltage problems.

[mfire1339]

My guess is, it's not tight enough if it's a single v-belt. I had to re-tighten Our's nearly every trip. REALLY tight

Mike

[gatorcruz]

I'm going to swap out the Alternator as I can't think of any other options... Problem occurs like clock work.

I pulled the old on and will let you know what happens after I install the new alternator.

[gatorcruz]

Installed new Alternator... started it up and let it run for approximately 15 minutes. Same thing... volts drop... followed by burning rubber smell and then some smoke... ????

I'm thinking it is a certain temp that i'm reaching when something comes on that is causing the problem but I don't know what it could be.

any help would be greatly appreciated...

Thanks.

JC

[gatorcruz]

quick update... located the source of the burning smell and what I'm certain is the electric draw... it was the Aux Radiator Fan... the plug was shorted and burned up. going to replace it and hopefully all will be well.

[nbounder]

While you're in there, look closely at the underside of the alt belt. It should NOT be shiny - shiny belts slip and get shinier. I think you done a good job of troubleshooting. I had a customer once who would be driving along and watched the voltage drop slowly but surely. Then the thing would die, start up OK, and go his merry way. Turned out the alt belt was shiny like my bald head. and would begin slipping till the voltage hit 10 volts, then the computer shut down.