Belt squealing on startup

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aengineguy

aengineguy

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Every time I start my Dart I have a slight amount of belt squeal. I have one belt around the crank, water pump and alternator. The crank pulley is about 20% smaller than stock, made from aluminum, the water pump is also aluminum and the alternator pulley is stock steel. Current fan is a 7 blade SS flex, but it did the same thing with a cheap lightweight fiberglass 6 blade. It is a pretty radical 408 with 550-580 hp. I have the belt as tight as I care to push it and don;t want to result in bearing failure. Does not do it if I burp the throttle or nail it as the rpm is high enough for the belt to rotate all the masses at that point. I guess my choices are double the belts.....expensive change, spray some kind of sticky goo on the pulleys and belt, go to a clutch fan (put some slippage thru the clutch on start) or rough up the grooves a bit.

Anyone else have this problem. Any other suggestions?

Thanks all!!
 
Get a better belt. I tried pullies and it did not go away. I have a electric pump and only run a single wire GM alternator. Tried several different belts until I ordered one from NAPA. She is quiet now. Well at least the belt is quiet.

What I found was the cheaper belts were thinner and bottom out in the pulley. The belt needs to tighten on the side of the vee.

I also tried a new alternator pulley it didn't help. The cheap belts also turn upside down after 7500 rpm's

I don't know if you can see it on the pics but the belt rides a tad higher then the edge of the pullies
 

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To the above point, there are different belt widths and some of the differences are very small. Don't mess with the belt dressing....sometimes it makes things worse. And keep an eye on that flex fan; the blades tend to crack and will come flying off if you do not catch that.
 
I have that problem with my 408. I believe that the March - aluminum pulleys, being smoother than stock steel pulleys add to the problem. Also if you are under driving the water pump pulley, that can add to the problem. -- Just my 2 cents - no technical info to prove it. -- Another possibility - Is your compression above 10:1 or so ? -
 

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aengineguy said:
Every time I start my Dart I have a slight amount of belt squeal. I have one belt around the crank, water pump and alternator. The crank pulley is about 20% smaller than stock, made from aluminum, the water pump is also aluminum and the alternator pulley is stock steel. Current fan is a 7 blade SS flex, but it did the same thing with a cheap lightweight fiberglass 6 blade. It is a pretty radical 408 with 550-580 hp. I have the belt as tight as I care to push it and don;t want to result in bearing failure. Does not do it if I burp the throttle or nail it as the rpm is high enough for the belt to rotate all the masses at that point. I guess my choices are double the belts.....expensive change, spray some kind of sticky goo on the pulleys and belt, go to a clutch fan (put some slippage thru the clutch on start) or rough up the grooves a bit.

Anyone else have this problem. Any other suggestions?

Thanks all!!
Click to expand...

I have the same set up as yours, and the same problem. Like yours, mine only squeals for a second on cold startup. It never squeals any other time so I just live with it.
 

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Your alternator is trying to get the voltage back up/put the amps back in that you took out when you cranked that beast. Belts get glazed and get less "grippy". CAREFULLY use some sandpaper to lightly break the glaze on your belt. Again, be careful. Or, just get used to a beast that screams a little when you wake it up.
 
if you have at some point got some anti freeze accidentally on your belts they will squeal.
it is slippery stuff and hard to clean completely.
..wash with soap, including your pulleys or replace.
 
bobg450 said:
Your alternator is trying to get the voltage back up/put the amps back in that you took out when you cranked that beast. Belts get glazed and get less "grippy". CAREFULLY use some sandpaper to lightly break the glaze on your belt. Again, be careful. Or, just get used to a beast that screams a little when you wake it up.
Click to expand...
I wonder if that theory could be tested by taking off the polarity wire from the alternator at startup?
 
bobg450 said:
-- just get used to a beast that screams a little when you wake it up.
Click to expand...
-- That's what I have done. --
icon14.gif
--
 
bobg450 said:
Your alternator is trying to get the voltage back up/put the amps back in that you took out when you cranked that beast..
Click to expand...

Maybe, but I doubt that, at least on initial fireup. In any case that is easy to prove yes or no. Just fire it up a couple of times with one field wire disconnected.
 
67Dart273 said:
Maybe, but I doubt that, at least on initial fireup. In any case that is easy to prove yes or no. Just fire it up a couple of times with one field wire disconnected.
Click to expand...
That's a good idea I wish I would have thought of that...
 
Take an old belt and cut it in half. Put the end of the belt in the vee of the pullies. if it bottoms in one of the pulies that pully is worn.

If it bottoms in all of them the belt is to narrow. Remanufactured alternators use the old pullies. some are 40 + years old. They do wear as do the other pullies.

Most of the times you hear a belt sqeal on start up it is due to a narrow belt bought at Advanced or Autozone combined with a worn Pully on a reman Alternator from the same place.

Over tightening the belt just causes more problems.

I fought the samething and I only have two pullies on my car. My belt was also turning upside down at over 7500 RPM's. All I did was go to a wider belt. I have hardly any tension on the belt now.

I can leave my alternator turned on, on start up and it don't sqeal. Mine also sqealed when started with the aternator turned off when turning it on while running . you could turn the switsh off and on while running and make it sqeal a couple of times. until the bellt got hot.

if you look at the pics above you will see I even added an adjustable sleeve to keep making tension adjustments when I was fighting this.

Just get a good belt and check your pullies.
 
67Dart273 said:
Maybe, but I doubt that, at least on initial fireup. In any case that is easy to prove yes or no. Just fire it up a couple of times with one field wire disconnected.
Click to expand...
I bet it wont make a noise this way.
 
Oldmanmopar said:
Take an old belt and cut it in half. Put the end of the belt in the vee of the pullies. if it bottoms in one of the pulies that pully is worn.

If it bottoms in all of them the belt is to narrow. Remanufactured alternators use the old pullies. some are 40 + years old. They do wear as do the other pullies.

Most of the times you hear a belt sqeal on start up it is due to a narrow belt bought at Advanced or Autozone combined with a worn Pully on a reman Alternator from the same place.

Over tightening the belt just causes more problems.

I fought the samething and I only have two pullies on my car. My belt was also turning upside down at over 7500 RPM's. All I did was go to a wider belt. I have hardly any tension on the belt now.

I can leave my alternator turned on, on start up and it don't sqeal. Mine also sqealed when started with the aternator turned off when turning it on while running . you could turn the switsh off and on while running and make it sqeal a couple of times. until the bellt got hot.

if you look at the pics above you will see I even added an adjustable sleeve to keep making tension adjustments when I was fighting this.

Just get a good belt and check your pullies.
Click to expand...

I just imagine that it is the belt width. I only have about 2000 miles on the pulleys and engine, granted, like you said, the alternator pulley may be years old. I am going to look at the groove to belt stance on each of the pulleys and then get a good belt or two and try. I too have an adjustable link with lock nuts, so the adjustment will stay in place. Thanks......
 
DON'T USE BELT DRESSING!!!!

It will stop the noise, but when it comes back, all the dressing in the world will not stop it!
ask me how i know.:D

Now as far as anti freeze on the belt, here is a trick that works....sometimes.

Note: THIS MAKE A BIG MESS OF YOUR ENG COMPARTMENT!
Get a small paper cup and fill it with "floor dry". with eng running slowly pour floor dry onto belt just before it roll under a pulley(don't matter which pulley) slowly pour it on the belt. you will have to do this several time. but it will fix it most of the time.

Now yours isn't making noise all the time, so i thing a new "Q" belt and checking pulley engagement is you best bet.
 
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