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Old 1st October 2012, 02:29 PM   #1 (permalink)
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hot alternator pulley fix needed, ideas?

Anyone ever have a situation where your pulley heats up ridiculously hot?

Upon running out of electrons one evening (got a jump, drove home), I tightened up the belt the next day because it was loose. I started up the motor to check the output and volts went right back to where they should be. To confirm it wasn't too tight, I grabbed the belt and flexed it and it seemed in range (~1/2", right?) but I also bumped into the alternator pulley and almost burned my hand it was so hot. This was after only running it at idle for a few seconds and a few gentle blips of the throttle, maybe 3k tops, and then shut down. 10 seconds tops...

I figured it was a bad bearing or an internal mechanical issue and the parts guys swapped me out another one, along with a new belt (the old one was heavily glazed). Put it all together but left the belt extremely loose but still tight enough to spin, and the exact same thing happened within seconds.

I called a friend today and he recommended pulling the wire off and seeing if it was something with a back EMF from the battery, so that's on the list of things to do.

The specs are single wire Powermaster alternator. It has a large wire leading from the output post to a 50A circuit breaker which is wired to the + post on the battery. It's a V-belt and the pulley is chromed if that makes a difference.

The interesting thing is that it had run flawlessly until recently, but nothing has changed on the motor. I figured it had to be the specific alternator but the replacements (belt and alt) doing the same thing has me puzzled. Any ideas?

Thanks in advance!

Chris
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Old 1st October 2012, 03:18 PM   #2 (permalink)
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Re: hot alternator pulley fix needed, ideas?

Hi Chris, was just checking your build thread for pics when your PM arrived...
Looking at the pics the belt does seem to be riding 'high' in the pulley groove, & the 'exposed' fiber cord which is meant to aid the grip factor might not be seated deep enough in the pulley groove... if thats the case then the solution is relatively simple, either widen the pulley grooves or fit narrower section belts... the chrome alternator pulley needs to go, a slightly larger dia pulley might also help having more surface area & better leverage ratio.. best of luck..

Last edited by jac mac; 19th January 2014 at 11:23 PM.
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Old 1st October 2012, 03:36 PM   #3 (permalink)
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Re: hot alternator pulley fix needed, ideas?

Thanks Jac, will try the belt and/or pulley swap. I know I didn't ask it specifically but I will now- the alternator is wired correctly, right? My understanding is one wire alt means one wire connected to the + post to charge it up.

It'll be next week before I get to spend any time with it but I am looking forward to getting it sorted.

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Old 1st October 2012, 04:06 PM   #4 (permalink)
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Re: hot alternator pulley fix needed, ideas?

Found this bit of info with regard to one wire alternators...belt width should be 3/8"..[ I think yours might be wider by pic] and one critical point which might be relavant to installation in some of our cars is the length & size of the wire used from alternator to battery..

PS, someone else was having problems with 'cooking' the alt belt/pulley on this site..was it Bill Mussara? cannot remember who it was for sure but Alan Watkins was one of several trying to sort it! Electrons etc are not my strong point, or should I say my voltage is dropping

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Old 1st October 2012, 04:39 PM   #5 (permalink)
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Re: hot alternator pulley fix needed, ideas?

Pulley overheating is usually caused by the belt slipping in the pulley.

If your battery is low or there is a greater load on the alternator it causes the alternator to be harder to drive which then places a greater strain on the belt to drive the pulley.

The chrome gives the belt an extremely smooth and difficult surface to grip onto causing it to slip and heat up.

Evidence is the glazed belt surface.

Dimi
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Old 1st October 2012, 11:22 PM   #6 (permalink)
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Re: hot alternator pulley fix needed, ideas?

Jac is right. I was the one with the overheating pulley. Mine would heat up just as yours is. It was throwing bits of the belt off and it was coating the front of the engine with the fine powdery black bits of the belt. It was intermittent at times, but would smoke the belt in a minute or two when it happened. I checked my wiring and all was O K. If this is a problem that has just happened and this is your initial startups, I would say to take your alternator to your local shop and ask if the "one wire" setup is correct for your alternator. If on the other hand this just started, and you have had the engine cranked before without this problem, it is your pulley/belt. Make sure your belt fits down in the V. It needs the surface area for traction. A skinny V will run on the top edge of the belt and it can't handle the load. I must have gone through 3 or 4 belts. Mine is wired from the battery to the starter. On the same lug on the starter I have two heavy gauge wires. One to the fuse box and one to the alternator.
I have a 351 Windsor. I discovered the engine builder tried to push off some parts he had laying around to finish the build. He put a Chevy pulley and crank sensor on the car.


Didn't discover this until we had some starter ring gear problems(great story for another time). Notice that the Vs on the chevy unit are not the same size. The skinny one with the black on it was the one for the alternator. As you can see it was riding on the to edge of the belt and burning it up.
I recently redid a lot of my electronic ignition which had nothing to do with the alternator, but what I did do at the same time, was change the pulley and the crank trigger/sensor to a Ford setup.The new 2V pulley was the only one I could find for the Windsor that was short enough. Clearance was about an inch with the Chevy unit. With the new one its 2-3 mm!! It is polished aluminum and a 2V belt. The V is a nice wide V. Notice how the belt fits right down in the Vs. Gets plenty of traction. The polished surface should not give you any problem. If your belt fits down in the V and still is slipping, take some 60 grit sandpaper and rough up the sides of the V.


After aligning the alternator and A/C units, I had to get new belts as the diameter of the new pulley was smaller(5") than the "jerry rigged" Chevy unit(7"). This resulted in the pulley on the alternator to turn slower, which I think was part of the problem. I took a string measurement of the length of the belt and went to Advance Auto and got 3 belts. One, the length of the string and two more. One and two sizes larger(to save trips back and forth). The belts that they supplied me have a brown fabric type coating on them. I left the original pulley on the alternator since it was a wide V, installed the belt that would fit correctly, tightened it as per usual and it hasn't slipped since. Runs fine and doesn't overheat.

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Old 2nd October 2012, 01:05 AM   #7 (permalink)
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Re: hot alternator pulley fix needed, ideas?

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Originally Posted by wbmusarra View Post
It was throwing bits of the belt off and it was coating the front of the engine with the fine powdery black bits of the belt. It was intermittent at times, but would smoke the belt in a minute or two when it happened.

Bill
Bill,

Thanks for the post, your symptoms sound identical to mine- it has run fine for a while but recently started throwing the dust and actually had a burning smell from time to time as well but I couldn't figure it out until working on the alternator.

I have noticed the belt rides high in the V on mine- moreso the belt may be too wide for the pulley than riding on only a portion of the belt. I will head back and see if I can get a narrower belt to seat it deeper in the slot. From your description, it seems ours are wired in a functionally identical manner with your alt wire coming off the starter lug and mine off the battery lug. I don't think it would make a difference and it has worked for ~300 miles or so.

It's a fairly stout wire but I may go back and re-run it with a larger gauge just for "fun". I am hoping a narrower belt and a little sanding of the chrome will address the issue, although I may even see if I can turn another pulley on my lathe- one a little bigger and with a wider V on it.

Chris
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Old 2nd October 2012, 11:14 AM   #8 (permalink)
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Re: hot alternator pulley fix needed, ideas?

Chris,
Just looked back at you pic of the setup. When you turn the new pulley, not only make it wider, but increase the diameter of it as well. That little diameter means it has to spin faster which will require more work. Give that pulley some surface area for the belt to work with. If you can, look for some pics of alternator pulleys on other build threads and see how big theirs are. I am at work, but I would guess they need to be about 3 maybe 4 inches in diameter. The ratio of those other pulleys to the alternator looks too high.What do you other guys think??

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Old 2nd October 2012, 12:19 PM   #9 (permalink)
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Re: hot alternator pulley fix needed, ideas?

Thanks for the suggestion Bill, I was thinking about that as well. I think I can spin something that large on my lathe, need to see if I have the stock for it on hand. Will probably pull the current one off to see what exactly I'll need to do to make my own before committing.

I will also check the pulley dia's on the Mustang to see what ratios they are running to gauge the proper overall size.

Thanks again for the thoughts,
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Old 2nd October 2012, 02:48 PM   #10 (permalink)
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Re: hot alternator pulley fix needed, ideas?

Yep , deeper / wider pulley grooves will be the ticket, you might even be able to widen the grooves in your current crank & W/pump pulleys enough to accomodate the belts your currently using [ it wont require much metal removal ] & then make a 'new' alloy pulley around 4" dia for the alternator.....dont need any 'bling' down in that corner of a GT40, only the road kill will see it!
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Old 2nd October 2012, 05:05 PM   #11 (permalink)
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Wink Re: hot alternator pulley fix needed, ideas?

Heres some handy info on sheaves --belts n pulleys---Notes on Pulleys and Belts
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Old 2nd October 2012, 07:51 PM   #12 (permalink)
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Re: hot alternator pulley fix needed, ideas?

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Originally Posted by ckouba View Post
I think I can spin something that large on my lathe.
Not sure how "weird" your dimensions are but I had a similar problem with generic alternator I bought from Summit. Did a little research and found another, wider, pulley on line somewhere for practically nothing. Just a thought.
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Old 2nd October 2012, 08:26 PM   #13 (permalink)
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Re: hot alternator pulley fix needed, ideas?

This is the larger diameter Ford Hi-PO alt pulley used on the 289s and Boss 302s:

Mustang & Shelby 289 HiPo Alternator Pulley

Available in steel (original) or aluminum from most any Mustang parts vendor. Proper belt rides "in the groove" and alternator does not overspeed at higher RPMs. We have these used by our installers on all of the Cobras/GT40s we sell.
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Old 2nd October 2012, 09:13 PM   #14 (permalink)
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Re: hot alternator pulley fix needed, ideas?

This is the larger diameter Ford Hi-PO alt pulley used on the 289s and Boss 302s:

Mustang & Shelby 289 HiPo Alternator Pulley

Available in steel (original) or aluminum from most any Mustang parts vendor. Proper belt rides "in the groove" and alternator does not overspeed at higher RPMs. We have these used by our installers on all of the Cobras/GT40s we sell.
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Old 2nd October 2012, 11:56 PM   #15 (permalink)
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Re: hot alternator pulley fix needed, ideas?

Quote:
Originally Posted by Mark IV View Post
This is the larger diameter Ford Hi-PO alt pulley used on the 289s and Boss 302s:

Mustang & Shelby 289 HiPo Alternator Pulley

Available in steel (original) or aluminum from most any Mustang parts vendor. Proper belt rides "in the groove" and alternator does not overspeed at higher RPMs. We have these used by our installers on all of the Cobras/GT40s we sell.
Thanks Mark. That looks the part, although I spent an hour or two with a chunk of alu in the lathe already. I have it faced and bored and now I am trying to figure out how to turn the V accurately in it. The alu version for $36 is certainly appealing though...

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Old 3rd October 2012, 10:51 AM   #16 (permalink)
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Re: hot alternator pulley fix needed, ideas?

Chris,
This is where I got my pulley from. They are very helpful and gave me the measurements so I could get the right part the first try. Believe it was around $70. Give them a call and they will fit you right up with the right part.
Small Block Ford Pulleys 289, 302, 351W, 351C

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Old 13th October 2012, 03:32 PM   #17 (permalink)
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Re: hot alternator pulley fix needed, ideas? FOLLOW UP:

A bigger pulley, slowing the belt, with a proper groove seems to have solved the issue. From my build thread:

Rcr 40-31

For the visual learners (problem on right, solution on left):



A big thanks to the group (Jac, Bill, Dimi, Rick) here for the ideas to pursue.

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Old 13th October 2012, 05:35 PM   #18 (permalink)
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Re: hot alternator pulley fix needed, ideas?

Quote:
Originally Posted by ckouba View Post
Thanks Mark. That looks the part, although I spent an hour or two with a chunk of alu in the lathe already. I have it faced and bored and now I am trying to figure out how to turn the V accurately in it. The alu version for $36 is certainly appealing though...

Chris
Chris, if you have a rotary table that you can set on the appropriate angle then you can use a small milling cutter (either in the lathe with the rotary table set just off the horizontal) or in the milling machine with the rotary table set just off the vertical. Turn on the lathe/mill and rotate the pulley on the table.

Works like a charm, have made several pulleys this way and it easily sets up the right angle for the groove and maintains it nicely throughout the machining operation. The milling cutter has to be very small though (so it fits in the groove). Just an idea.
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Old 13th October 2012, 07:52 PM   #19 (permalink)
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Re: hot alternator pulley fix needed, ideas?

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Chris, if you have a rotary table that you can set on the appropriate angle then you can use a small milling cutter...
Thanks Cliff. That was Plan B if I hosed up the operation on the lathe. I was lucky enough to have a compound cross slide (I think that's what it's called) on my lathe when I picked it up so cutting the groove was just a matter of setting up the proper angle on it and cutting the groove to the correct width and depth.

A while ago I also stumbled upon a very reasonably priced 10" rotary table which also does the angle thing. It has been very useful when I've needed it.

Chris
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