Alternator Belt Dilemma

[Tim Kay]

Two belts gone inside 100 miles. Seems the belt is sticking or sliping on pulleys.

I begin to smell burning rubber (and no, it's not the rear tiresepper: ) and the alternator gauge drops by 1-2 amps charging. After a couple of minutes at cruising speed the amps go back up and smell subsides. Stop car, idle, then proceed from a stop and the amps drop, the smell of the belt comes back until back to cruising speed then the amps come up and the smell of the belt goes away. Obviously, the belt breaks after several of these cycles.

Suggestions...

 

[Ron Earp]

And the belt is tight? If not adjust your alternator and get the belt tight.

If the belt is tight and you are still getting some sticking and sliding then replace the alternator as it is probably failing. Saw this scenario about 1.5 years ago on my race car and should have known better.

One more question: are these V belts or serpentine? If v belt make sure you have the right series. I was once trying to use a 17 series belt where a 15 series should have been - resulting in slipping belts.

 

[Tim Kay]

Thx Ron,<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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Yes, the belt is tighten correctly. Alternator fairly new but if going bad, what is the symptom? Is the rotation tightening or restricting thereby allowing the belt to slip on the pulley? <o></o>
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Wrong V-belt is my thought, maybe too narrow and too deep in the pulley? Not sure the difference of the 14 and 15 series, I assume width?<o></o>

 

[Phil]

Tim
Check your alternator pulley, if the bottom is shiny then your belt width is too narrow. I have seen this turn pulleys blue with heat. Also an outside possibility is that you have a major intermittent short that is putting the alternator into full field. This can draw up to 20 hp from the belt. I would suggest hooking up a voltmeter temporarily as you drive and see if there is a substantial voltage drop to check for this. As Ron also said the alternator may be bad and again this will draw substantially on the belt, it may be as simple as a faulty regulator.
Good Luck
Phil

 

[Ian Anderson]

Tim

Presumably something else os also on the belt perhaps water pump - how are the bearings on that? Perhaps it is showing up as a low amperage because the belt is draging on the ??Pump??.

If not a short could be the cause - perhaps first place to check is on the brake light circuit - (Quite often not on a fused circuit) sitting with your foot on the brake witha short wll drain the battery in a big way

Ian

 

[Tim Kay]

Great suggestions, I will check for a short next. I first went the simple route and change belts for remedy. If it persist then the direction of a short sounds likely.

Thanks and I will post result in the next day or two.

 

[Rick]

If the belt is too narrow it will only contact the pulleys on the flat at the bottom of the "V". Or as stated, if one accessory (alt or WP) binds up the crank will burn a flat spot on the belt and ultimately burn through it.

 

[Dimi Terleckyj]

One question is , has this only just started after lots of miles/time of trouble free driving or is this the first time the car has been driven.

If its the first time it could be belt tension or pulley misalignment or the wrong belt for the pulley.

If its after a long time of driving and has just started to happen then the most likely thing is that some component in the belt driveline is starting to seize up and putting excess tension on the belt causing it to slip and burn.

If you have any idler pulleys or guides make sure their bearings are not seized or on their way out.

Bearings that are about to fail can rotate freely and then suddenly jamb and then freely rotate a number of times before letting go altogether.

Dimi

 

[Tim Kay]

Rick, to narrow is what I am hoping. Put on wider belt to see.

Demi, this is a new issue on a new setup, less than 100 miles. Alignment and idler pulley seem fine. I will keep an eye on your suggestion in this regard.

Thx guys :thumbsup:

 

[SteveB]

Tim

I had a similar problem. After a start up or a period at idle with some loads on the electrical; it can add up wth aircon,fans,fuelpumps efi or lights.
The alternator is trying to recover and runs at max amps loading the belt.I tried a larger pulley on the alternator, although it cured the slipping and squalk but made the discharge at low revs worse.
The smaller pulley was a chromed item so I gritblasted the vee faces and re tried the original setup. This gave the pulley more grip and cured the problem.

Steve

 

[Tim Kay]

SteveB, great suggestion, I too have a chrome pulley. I will do the same grit blast and give it a go. Thanks

 

[Tim Kay]

Resolve after 100 miles:
1) New, wider belt (although the prior belt was new)
2) Alternator pulley, inside surface, machined

Seems the previous belt was slipping because it was too deep in the alternator pulley, the chrome surface may have contributed as well. I added a wider belt (+1\8") and machined .050 off the inside surface of the pulley allowing the wider belt to seat better and removing the smooth chrome surface.

Possibly, another contributing factor may be the configuration of my alternator mounted in the upper left, off the head, allows the belt to make contact on only 20-25% of the pulley diameter (my a-belt encompasses the water pump, crank and ac-pump pulleys). In other words, if more contact of the belt on the pulley were possible then less likely the the belt would slip.

I

 

[Bill Kearley]

I hate to say it but your problem is probably not gone, 20% contact is not enough. A car not driven enough or frequently will have high loads placed on the alternator. Assuming all berrings are good and pulleys are in alinement ???. look forward to reconfigure belt routing to achive a minimum of 40-45% contact

 

[Tim Kay]

Bill, I believe your right.

 

[Tim Kay]

Bill was 100% correct.

Initially after the modifications to the pulley, as noted above on 10-4-08, the belt ceased to slip but only for a short period. I took the time and rerouted a new belt to assure 60-70% contact with the pulley. Have not had an issue in over 500 miles :thumbsup: