Squeeling V belt and CVF alternator

-
Justin Angle

Justin Angle

Well-Known Member
Joined
Jun 16, 2019
Messages
82
Reaction score
26
Location
St. Louis
Anyone running a CVF high amp alternator and have had problems with the alt belt squeeling??

Long story short, I did the MAD ammeter bypass and switched to electric fans and put a new CVF high amp alternator and have really had belt problems ever since. I've tried the gates 7470 and the dayco 15475 with no luck getting them not to squeak. Recently I had a gates 7470 last about 25 miles before it started squeeling. It's a 360 with no AC. I've tried unhooking the charge wire to see if it's the load causing it to drag but it dosent seem to make a difference.

At idle with the electric fans, fuel pump, msd, headlights on, and radio, it's showing about 55amps with amp clamp on alternator charge wire. The alternator pulley and water pump pulley seem to spin fine with no drag and everything is aligned with a straightedge and has to be near perfect. Any ideas or similar experiences? I talked to CVF briefly and they said their alternator pulley "should" work with OEM pulleys.

20240525_090314.jpg
 
There are different width belts.

My recolection is the OEM belt for our small blocks is a fraction narrower then the typical belts.

You could try belt dressing but my luck with it is less than stellar.

Are you sure the alt is tensioned correctly?
 
The squealing belt issue is about how you tension the belt. I went thru this on my Duster, same setup but a stock alternator on a 340. I ended up making a bracket that bolts to the alternator to accept a breaker bar into it to actually tension the belt. I got it tighter than by pulling the alternator by hand, no squealing belt since. At the time I couldn’t find breaker bar and used a torque wrench to about 50 foot pounds and the alternator moved another 1/2” to 3/4” in the adjustment slot from where it was when I was just pulling the alternator by hand to tension. I also have cycled thru both Dayco and Gates belts as you did, but I retained the Gates as the Dayco is foreign made and stretched.
 
There is also a belt called Gate Back that for some reason stopped the squeezing on 2 cars
 
Too much tension on a v belt will wear your water pump out in no time.
Belt squeal when the belt is tensioned correctly is either over heating the belt, wrong angle (belt should be about 2degrees wider than the pulley angle) or over loaded and that’s when you go to a dual belt system. Look at the high amp alternators on police cars from back in the later 70’s.

Belt dressing is putting lipstick on a pig.
 
Isn't there a belt deflection check to determine if the belt is at it's proper tension?
1726229687312.png
 
Thanks for all the responses. When I put the fresh Gates belt on I started with what felt like proper tension though it still squealed so I pulled it tighter and tighter by just picking up on the alternator until it quieted down. It did make me a little nervous about water pump bearing longevity etc..
It definitely sounds to me like it's coming from the ALT pulley.
Inside the groove of the CVF pulley has a slick glossy painted finish compared to an oem one...Thinking that could be a contributing factor..
Dana67Dart said:
There is also a belt called Gate Back that for some reason stopped the squeezing on 2 cars
Click to expand...
Do you have a part number by chance?
 
Justin Angle said:
Thanks for all the responses. When I put the fresh Gates belt on I started with what felt like proper tension though it still squealed so I pulled it tighter and tighter by just picking up on the alternator until it quieted down. It did make me a little nervous about water pump bearing longevity etc..
It definitely sounds to me like it's coming from the ALT pulley.
Inside the groove of the CVF pulley has a slick glossy painted finish compared to an oem one...Thinking that could be a contributing factor..

Do you have a part number by chance?
Click to expand...
Maybe try lightly roughing up that pulley surface.
 
Just get a larger pulley for it. The tension is easily set by twisting the belt with 2 fingers at the middle of the longest run. If you can turn it upside down its to loose. I usually do a quarter turn. .Even though the belt is straight. It looks like the Alternator pulley is angled a little straighten it or the belt will get hot and slippery.
 
Oldmanmopar said:
Just get a larger pulley for it. The tension is easily set by twisting the belt with 2 fingers at the middle of the longest run. If you can turn it upside down its to loose. I usually do a quarter turn. .Even though the belt is straight. It looks like the Alternator pulley is angled a little straighten it or the belt will get hot and slippery.
Click to expand...
THIS
 
This is my thought, is your belt bottoming out on the floor of pulley? Look at the floor of the pulley, is it shiney? All of the floor or the edges? If it is, that's why it is squealing. Your belt should be above the or stand proud in the pulley. Friend of mine just had this same problem with aluminum pulleys, belts were bottoming out.
 
Two concerns to address
1) Syleng1 is right about too much tension can damage bearings in water pump and alternator.
2) Justin, you state you keep “picking up on the alternator” to tension the belt.

The factory service manual has a belt tension spec and a belt tension tool that is a lever that hooks to the alternator to get to that tension. Therefore you are not even close to proper belt tension with your method, and not at risk of water pump damage yet. Make a way to get a lever to hook onto the alternator to get to proper tension. I used 50 foot pounds in a torque wrench as what felt good for what I made up, still have belt deflection with a much tighter belt and NO belt squeal.

Also I think the water pump is where the squeal is because look at how little belt contact for a component that pumps water… like a dynamometer… only belt that doesn’t wrap around the pulley more than 1/4 of the circumference.
 
Failing water pumps are known for making a unique squealing or chirping noise. You may want to check the pump, take the belt off and spin the pulley by hand if it sounds "grainy", you know what comes next.
 
A belt tension tool for V belts.
And there used to be 3 different automotive series of belts. 13,15 and 17 or 5,7 and 9. Skinny belts 13 or 5 series fit lower in the groove. I used to regularly throw belts back in my nitrous days. A skinny belt did the trick. Maybe a different series would help?

20240913_130612.jpg
 
Ditto on the pulley size. It looks undersized. A larger pulley has more belt grip area and provides more leverage to hold the shaft without slipping. It will also slow it down to typical alt rpm relative to the crank speed. I guess they used the tiny pulley to try and have better charging performance out of the alt at lower rpm.
 
Well, wondering if 1000 lbs of belt tension stopped the squeal.
 
It’s not going to help much but it could be the belt and a different belt and/or cleaning the pulley and belt might help? I didn’t have squealing from either my PS belt or alternator belt but replaced both since they had been on for quite a while. Thought preventative maintenance was a good idea (and belts aren’t expensive) considering I was going on a long drive. Bought new new Gates belts (same as the ones already on the car) and got a squealing when starting the car and getting it off the fast idle setting. Played with the tension of both but still had a squeal. First reinstalled the PS belt with the old one and still had the squeal. Played with the tension again of the alternator belt and still had the squeal. So then reinstalled the old alternator belt and the squeal was gone.
 
Dana67Dart said:
See...

If it ain't broke don't fix it!
Click to expand...
Was going to ignore this but… after sitting on that idea for 4 hours, I decided I have to comment. Why? Because that saying is only going to last the life of that belt… once that belt breaks or starts to squeal… the OP will be in this boat again having not solved it properly the first time.

The answer is “Read the big factory service manual” and it will tell you everything you need to know. Every time I ignored it my Mopar friend would always ask “What does the big factory service manual say?” Guess who had to admit he didn’t open it, and guess where the answer was… it was in there… read belt tension and it shows a belt tension spec, if you have the tension gauge you will find that without leverage to tension that alternator, you are not even close to spec just “pulling up the alternator by hand”. The manual even shows a lever on the alternator to tension the belt. I’m not saying the method of pulling up alternator by hand is totally wrong, because if I break a belt on the side of the road that’s how I would tension a replacement I carry in the trunk, and I know that until I get back to my tensioning tools (a form of leverage) it will work to get home and it will squeal until tensioned properly.

Back to rant, last summer I posted about questionable cooling on my 340, and everyone asked “Is it overheating?” And because my answer contained “No” I was disregarded with “if it ain’t broke don’t fix it” by most responders. I opened the big factory service manual and learned that my 340 should have a 7 blade 2-1/4 pitch 18” fan, and I had a 7 blade 1-1/2” pitch 17” fan, correct for slant 6 AC car… So I put the correct specified fan on it and the car ran 180 degrees on a 90 degree day with spirited driving this summer, never reaching last summers operating temps of 200 degrees on 80 degree days. Is this rant long, probably, but if I had “left it alone” as advised maybe it would have overheated this summer instead of enjoying the car…

My advice, please just lever that alternator until the new Gates belt is tighter than when you try by hand and report back. I hate chasing problems when I’m trying to have fun, and I believe you want reliable fun or you would not have changed the belt.
 
I'm probably wrong but is the belt shown in the picture inside out....never seen one with the segmented section on the outside, those "toothy" bits usually go into the V of the pulley don't they??

I only ask this because your picture looks to show a symptom we are used to seeing here in Europe.
if i run a European segmented v belt measured in (mm cm etc) on US mopar pulleys /water/alt/balancer the width and angle of V of the belt is wrong, the depth of the V of the belt is wrong and the widest outermost width of the belt is wrong.

and so when you tension the belt properly the tautest bit is the smooth side, and the segmented bit is running in the base of the valley of the V and not hard against the sides. SO the action of the engine turning causes the belt to flip inside out.

hence when someone says, lost a belt or slipping belt, this is what i look for. Namely t,he segmented tooth like section of a modern V belt, visible on the outside rather then wedged into the V.

but as i say could be wrong maybe your belt is just like that.

they do slip and make a noise when this happens, because you are running on a belt surface that was never supposed to see the metal of the pulley.

obviously i outlined a specific circumstance where the belt if fitted correctly, its flips and caused a problem.

but if you fit the correct width and V shape belt, inside out, id expect similar.

not saying you have, I have just not had the experience of a belt like the one shown in first post

one last thing
making 55 amps takes more effort than making 35 amps so your alternator will be stiffer to turn over, especially if the pulley is smaller than standard.
they could have used a smaller pulley to achieve an idle speed alternator rpm, that will charge.
is that what they have done here?

a bigger pulley slows alternator down a bit for a given engine rpm, and will make turning it to make 55 amps an easier job for the belt, basically more surface area of pulley in contact with the belt and an and easier gearing ratio between balancer pulley and alternator pulley.


Dave
 
Last edited:
Dave999 said:
I'm probably wrong but is the belt shown in the picture inside out....never seen one with the segmented section on the outside, those "toothy" bits usually go into the V of the pulley don't they
Click to expand...
Belt is correct side out. Some manufacturers do that to make it easier to turn around smaller pulleys. I have had a few over the years.

I have also had the belts as you describe with segments on the inside. My understanding is it helps let trapped air out so it does not squeeze out making a squeak.
 
ah l learn something.... many thanks....

probably a gearing problem then.... or indeed it is running on the base of the V due to a width problem.

i.e the in-built i'm now worn out and too narrow squeak, is there from day 1
Dave
 
Dave999 said:
or indeed it is running on the base of the V due to a width
Click to expand...
I had mentioned that. My recollection is the stock belt is narrower than the replacement belts.

I just looked at 2 belts one was 0.44" and the other was 0.41"
 
Thanks to all who had replies. I scuffed the inside groove of the alternator pulley to give the belt more bite. Before it had slick glossy finish. Also I tensioned the belt as @Wvbuzzmaster suggested. I The latter was the fix I'm sure. i now have about 150 miles on the car and it's quiet as can be and alt pulley feels cooler to the touch after driving.
 
You must log in or register to reply here.
-

Back
Top