Alternator screeches, dim lights

[Cooneytoones]

Sent: 10/5/2005

A question to ponder about my alternator.....On my trip to Talladega, my alternator belt started screeching..( my dash Volt meter does not work)..Possible but not for sure alternator (which is new) was locking up at intermittent loads, also have installed a new voltage regulator. Belt that was on there was a Gates (can't remember the number something like 7404) but it's the correct one, the book at Napa lists it for the 1976 440-3, and it cross references with the Dodge part # in the Dodge manual. Now that belt is ribbed on the drive side of the belt, so I may question if it's the correct one again later in the story. As I said got an awful screech from the belt possibly the alternator locking up, but with out a load...) no load daytime nothing on....electrical not clothing..... brand new battery also installed.   Belt flipped was torn at the ribs, some of the ribs missing. Replaced belt with the same gates belt... about 4 hours later belt started screeching again, this time lights were on and it was dark. Lights were OK and bright. Tension on belt was good. did it 2 or 3 more times about 15 or 20 minute intervals , and lights went dim...... belt went MIA. Stopped at a campgrounds for the night.....Replaced it with the PS belt that came with my rig, same size on the pulley groove but just a plain (smooth on the inside) V belt, no ribbing, and about an inch bigger in circumference, which I had enough adjustment on the alternator to adjust properly....ran all the rest of the way to Talladega ( about 150 miles) in daytime..All was fine , except for the driver.....On the return trip home all was working fine, when I put my lights on, the headlights were dim..about 1/2 power....checked the battery not running 12.5 volts, at an idle no load14. 25,  and at load (just (dim) lights) at idle 13.85v just on the main switch.... when switched to dual drop to 13.25v.....now that was all at idle, at about 1200 rpm 14.35 volts on dual....this sounds normal to me. So why are my headlight dim? They weren't dim before I lost the second belt.... Why is this belt, which is not supposed to be the correct one, working better than the correct one? Not a screech on the trip home or the 150 miles there total of 700 miles on the wrong / right belt.... Could the ribbing have something to do with it? Seems to tear the ribbing. pulleys are aligned and no sharp edges......Could a field wire have come off or be loose  from the alternator? Could alt. be putting out !/2 power........ Could I have lost a ground on my lights when the belt shredded? All other systems work as they should, drove for over 3 hours with dim lights and the battery was, and still is at 100%.....Any answers on what to check....I want to bench test the Alt. then from there.....I'm not sure what to do if the alt. is OK....I think I'll keep the smooth belt.....any suggestion??? I;m dim witted on this one...

DimTimmy

[denisondc]

Sent: 10/6/2005

Without seeing how your alternator is mounted, my first suspicion would be a faulty alternator - whose rotor is coming in contact with the stator under some conditions maybe. I have seen this happen when the stator got loose from the case of an alt. Second suspicion: would be that the alternator mount is cracked or has come slightly loose - and while it keeps the belt seemingly tight when stopped, is allowing the belt to loosen under engine vibration. If the alt. vibrated enough it could allow the belt to invert itself in the pulley groove.
Third thing I would check for - is there something that could be hitting the belt when everything is moving at high-way speeds; i.e. does the radiator fan wobble, or do any of the other pulleys that belt runs over wobble?
Its normal for V-belts to have a ribbed -inside-. This is to keep the gripping area large enough, but to have the belt develop less heat from the flexing it undergoes. That feature obviously isn't a bid deal, since some belts have the ribs, others don't.

[denisondc]

Sent: 10/6/2005

As for the dim headlights, try running a new wire from the frame up to the headlamp housings, or wherever they are grounded. That is what you would probably want to do anyway if you did find the shredding belt had ripped a wire free.

[Cooneytoones]

From: cooneytunes
Sent: 10/6/2005 9:32 PM

Thanks Denison.....I think it might be a faulty alternator. It's a new rebuilt (Napa version of OEM Alternator) identical to the one that came off ) I'm going to take it off and have it bench tested...If it's bad, I think I'll upgrade to the Bosch (new not rebuilt)...as far as the fan and radiator fan and fan clutch are tight, no wobble or slipping of P/S belt which is the main drive for the water pump... all the pulley's on the crank run as true as possible...the only pulley for the alternator is  on the crank shaft and the alternator itself (no idler)....I thought of the bracket too, and checked that, bracket it self seems solid, now the adjusting bolt (on the slide part of the bracket) is another question, that may have slipped a little before the first two belts broke, bolt itself is getting rounded and only a 6 point socket or a flair wrench will work on it....I am going to change that ASAP. Haven't checked for a lose or missing wire, but your probably right, needs a better ground.....Will get to it this week-end and let you know what I find. I also broke a High Pressure Hydo-boost line from the Power Steering Pump to the Hydo-boost. That is what started this whole fiasco...Had to have a new one made, could not find the part, had it made of 3/8 rubber and the correct new ferrals put on the end, and had to re-route and tie it back and re-enforce where it would hit on metal, It rubbed a hole in the original line right under the bracket that holds both the feed and the return High pressure hoses to the frame....but that's another post and the problem ( with the P/S) is solved. Also had to bleed the Power Steering Pump....it was full of air...I'll post that procedure on the post where the guy asked about his P/S pump growling...low fluid level and air will 'cause that, and there is no way to get the correct fluid level without bleeding it.

Thanks again,
Timmy

[Froggy1936]

If you find that the alternator is mechanical OK  a short in a non fused section of the light circuit or charging circuit could dim the lights and load the alternator enough to make the belt squeal any squealing belt will fail shortly especially at high speed   Frank