Pulley Failure

[Locobob]

So a couple of years ago my tensioner went bad and I rebuilt it using a combination of stuff including some L98 parts and this aluminum pulley from UPR products (the pulley specs as a 85-93 Mustang ultra light tension/idler pulley). I remember I followed the tensioner rebuild project of someone on here, so if you have this pulley I suggest you check it. I can't think of any reason other than poor build quality as the cause, there are actually several holes although you can only see the one in the pic. The belt shows some damage too, I was noticing some odd coolant temp and voltage fluctuations which is why I started poking around. Guess I'll go back to the factory pulley.


http://www.zr1.net/forum/picture.php?albumid=432&pictureid=3973

[Ccmano]

Bearing failure?
H
:cheers:

[Locobob]

Bearing failure?
H
:cheers:


Possibly... I have been noticing a silvery oily residue under the air horn and around the general vicinity of the belt. Although I think that is from a leak in the A/C system which is another area I need to address and that could also account for belt slippage.

[XfireZ51]

LB,

Looks like it wasn’t worth the extra hp.

[Ccmano]

Judging from the hole in the pulley (which is aluminum) looks like it froze and the belt wore a hole in it, might be the source of your silvery residue?
H
:cheers:

[Locobob]

Judging from the hole in the pulley (which is aluminum) looks like it froze and the belt wore a hole in it, might be the source of your silvery residue?
H
:cheers:


Hmmm, that's a good possibility

[Paul Workman]

Judging from the hole in the pulley (which is aluminum) looks like it froze and the belt wore a hole in it, might be the source of your silvery residue?
H
:cheers:

Yup. Beat me toit!! Pully seizing up.

Bob: I replaced mine with a GM pulley for a C4 LT1. Works no for over 10 years! Also, Jerry's Gaskets has ZR-1 pulleys, IIRC.

[Jagdpanzer]

After looking closely at the photo appears it could have started as fatigue crack.
Is the center section of the pulley solid or spoked?



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[efnfast]

Pretty sure Jim Voter had that exact same pulley fail on the way home from BG

[HAWAIIZR-1]

It’s hard to imagine that billet aluminum is weaker than plastic (stock) and I agree it has to be bearing failure with a seize that heated and burned by the belt friction. It would seem that would be noticeable though. I’m tempted to go back to stock myself. I guess another reminder to make America great again and we need better quality parts overall and stop outsourcing if this is from China.

I can’t remember the Dynomite post. Was it bigger and needed and larger belt too? If same sized belt used it could cause more tension on the pulley than it should have? Thanks for sharing since some of us did this mod.


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[Locobob]

One of the symptoms I had was periodic low voltage at idle. Sometimes I'd be sitting at a red light and the voltage would drop down to like 8-9 and the stereo would shut down. It was an intermittent issue and my thought was this was due to belt slippage, possibly from my leaky A/C system. I had my alternator rebuilt a while back and that made no difference so I eliminated that as the possible source. Now I'm thinking maybe it was the pulley occasionally seizing up and dragging down the belt speed at idle. Guess we'll see once I get that replaced.

[Dynomite]

One of the symptoms I had was periodic low voltage at idle. Sometimes I'd be sitting at a red light and the voltage would drop down to like 8-9 and the stereo would shut down. It was an intermittent issue and my thought was this was due to belt slippage, possibly from my leaky A/C system. I had my alternator rebuilt a while back and that made no difference so I eliminated that as the possible source. Now I'm thinking maybe it was the pulley occasionally seizing up and dragging down the belt speed at idle. Guess we'll see once I get that replaced.

Was anything leaking on the serpentine belt?
How many miles on your Tensioner Aluminum Pulley?
Did you modify the Tensioner when you installed the Pulley?

I checked three Belt Tensioner Aluminum Pulley Installations and all is well.
One Tensioner pulley with 6,000 miles. I removed the 6,000 mile Tensioner Aluminum Pulley and checked the bearing which was found had no play and very smooth when rotated.

I have been noticing a silvery oily residue under the air horn and around the general vicinity of the belt. Although I think that is from a leak in the A/C system which is another area I need to address and that could also account for belt slippage.

What is that all about?
Belts and oil do not mix :p
The problem of an oily belt would be between the belt and the Harmonic Balancer driving the belt and Alternator Pulley, Power Steering Pulley, Water Pump Pulley, AC Pulley getting power from the belt.

Check the Bearing and what is meaning of oily residue?
Even if the belt was oily the Tensioner Aluminum Pulley is free wheeling so I would expect no issues. Spin the Tensioner Aluminum Pulley before you remove the Tensioner to see if any play, resistance, interference.

[Locobob]

Was anything leaking on the serpentine belt?
How many miles on your Tensioner Aluminum Pulley?
Did you modify the Tensioner when you installed the Pulley?

I checked three Belt Tensioner Aluminum Pulley Installations and all is well.
One Tensioner pulley with 6,000 miles. I removed the 6,000 mile Tensioner Aluminum Pulley and checked the bearing which was found had no play and very smooth when rotated.



What is that all about?
Belts and oil do not mix :p
The problem of an oily belt would be between the belt and the Harmonic Balancer driving the belt and Alternator Pulley, Power Steering Pulley, Water Pump Pulley, AC Pulley getting power from the belt.

Check the Bearing and what is meaning of oily residue?
Even if the belt was oily the Tensioner Aluminum Pulley is free wheeling so I would expect no issues. Spin the Tensioner Aluminum Pulley before you remove the Tensioner to see if any play, resistance, interference.


I rebuilt the tensioner and installed the pulley about 2 1/2 years ago... probably about 10-15K miles. The belt itself doesn't feel oily so we'll see.
Do you have the same aluminum pulley? Could be I just got unlucky and got a bad one.

[Dynomite]

I rebuilt the tensioner and installed the pulley about 2 1/2 years ago... probably about 10-15K miles. The belt itself doesn't feel oily so we'll see.
Do you have the same aluminum pulley? Could be I just got unlucky and got a bad one.

I think I have the same pulley and someone here said Jim had failure of same pulley but am not sure of that. Did you modify the tensioner for installation of the pulley?

We have to wait to see what you find when you remove the Tensioner.
Before you remove the Tensioner check the Pulley to see if any play, resistance, interference.

The Serpentine Belt is just a bit narrower than the riding surface on the pulley (check that surface for wear compared to the original surface).

It could be a fatigue crack between spokes as Phil Suggests.

[dredgeguy]

I think I have the same pulley and someone here said Jim had failure of same pulley but am not sure of that. Did you modify the tensioner for installation of the pulley?

We have to wait to see what you find when you remove the Tensioner.
Before you remove the Tensioner check the Pulley to see if any play, resistance, interference.

The Serpentine Belt is just a bit narrower than the riding surface on the pulley (check that surface for wear compared to the original surface).

It could be a fatigue crack between spokes as Phil Suggests.

On the way back from BG Jim had complete failure of the pulley. It locked up and was sawed in half from the belt. Jim, always prepared had a spare pulley and a spare belt in the car and made the repair in a small shopping center in West VA. Repair done in 35 minutes!

[QB93Z]

Thanks for posting the picture Charlie. And thanks to Charlie and Dan for retrieving all the tools I dropped in front of the engine while doing the repair.

My failure was a frozen bearing on a stock, plastic pulley with at least 60,000 miles on it. I have not changed it since I bought the car. This is the second stock pulley bearing I have had fail. The first was on my 1990 ZR-1 and was a few years ago.

This is why I carry a spare pulley and belt when I travel. The repair is straight forward and I can get back on the road easily. It helps to have a long 18mm combination (open end-box end) wrench to reach the tensioner bolt. It is harder to get the bolt with a socket wrench.

The only problem is the engine is HOT and I got a couple of burns this time. Even with gloves on, you have to reach in among the coolant piping. I have added heat resistant sleeves to my travel tool box.

Jim

[Dynomite]

Thanks for posting the picture Charlie. And thanks to Charlie and Dan for retrieving all the tools I dropped in front of the engine while doing the repair.

My failure was a frozen bearing on a stock, plastic pulley with at least 60,000 miles on it. I have not changed it since I bought the car. This is the second stock pulley bearing I have had fail. The first was on my 1990 ZR-1 and was a few years ago.

This is why I carry a spare pulley and belt when I travel. The repair is straight forward and I can get back on the road easily. It helps to have a long 18mm combination (open end-box end) wrench to reach the tensioner bolt. It is harder to get the bolt with a socket wrench.

The only problem is the engine is HOT and I got a couple of burns this time. Even with gloves on, you have to reach in among the coolant piping. I have added heat resistant sleeves to my travel tool box.

Jim

Hi Jim ........Your pulley(s) that failed were stock pulley(s) rather than the Tensioner Aluminum Pulley Locobob had fail. Great Photos...... and that was one reason I went to the Aluminum Pulley as the Bearing is easy to replace.

It still appears like a Fatigue Failure of the Aluminum Tensioner Pulley as Phil suggested. If no other type of interference or bearing failure is found by Locobob.

I also have the Water Pump Aluminum Pulley which has no belt retaining ridge making it much easier to remove the Serpentine Belt (back of belt rides on pulley) from that Water Pump Aluminum Pulley first.

I did modify the 18mm combination wrench heating and bending the box end straight making it much easier to use the box end on the Tensioner 18mm Bolt.

[Paul Workman]

My failure was a frozen bearing on a stock, plastic pulley with at least 60,000 miles on it. I have not changed it since I bought the car. This is the second stock pulley bearing I have had fail. The first was on my 1990 ZR-1 and was a few years ago.

This is why I carry a spare pulley and belt when I travel.
Jim

Hmmmm... Thanks 4 the tip, Jim! I carry a belt - never thought about a pulley. (Course...where does it end?? (spare parts, I mean...)

[Dynomite]

Hmmmm... Thanks 4 the tip, Jim! I carry a belt - never thought about a pulley. (Course...where does it end?? (spare parts, I mean...)


You can preventively maintain it at home or carry spare parts on the road :p

[Paul Workman]

You can preventively maintain it at home or carry spare parts on the road :p

Yup! Totally agree - like changing oil or brake pads, or alternators too, for that matter. Mine died at around the mid 40k miles. So, mebby it would be a good idea to change them out at about 40-50k miles as a matter of routine. But, non-OEM parts are "...like a box of chocolates. You never know what you're going to get!"

[Locobob]

Well I pulled the belt off and the pulley seems to spin freely by hand... although that doesn't mean it doesn't perform differently under load. The belt doesn't look terrible, its a little chewed up in a couple of spots. I need to check my notes for the belt size, I have the underdrive pulley set from SRP. I have Gates and Dayco pulleys available locally. I believe Gates is supposed to be the gold standard but with all the outsourcing going on who knows anymore. I did rebuild the tensioner a few years ago because it was chattering badly, I haven't seen any sign of it bouncing around since so I'm guessing that part of the assembly is okay.

[Dynomite]

Well I pulled the belt off and the pulley seems to spin freely by hand... although that doesn't mean it doesn't perform differently under load. The belt doesn't look terrible, its a little chewed up in a couple of spots. I need to check my notes for the belt size, I have the underdrive pulley set from SRP. I have Gates and Dayco pulleys available locally. I believe Gates is supposed to be the gold standard but with all the outsourcing going on who knows anymore. I did rebuild the tensioner a few years ago because it was chattering badly, I haven't seen any sign of it bouncing around since so I'm guessing that part of the assembly is okay.

Did you modify the Tensioner such that the pulley inner hub was not in contact with the tensioner at any place? Take a close up photo of the Aluminum Pulley belt surface. Also a close up photo of the failed surface.

Was the Pulley Bearing Snap Ring on the outside or toward the engine?

[Locobob]

Did you modify the Tensioner such that the pulley inner hub was not in contact with the tensioner at any place? Take a close up photo of the Aluminum Pulley belt surface. Also a close up photo of the failed surface.

Was the Pulley Bearing Snap Ring on the outside or toward the engine?


I'll have to take a look at that once I get the tensioner out. I don't recall any modification being necessary. The pulley has multiple holes in it, all around, so obviously it was turning some and then locking up at times.

[Dynomite]

I'll have to take a look at that once I get the tensioner out. I don't recall any modification being necessary.

https://cimg0.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/600x500-1/80-11b381b7_0244_4790_9e74_503596af4add_1__a6f008b692 fc1747189b859532946d5bc6a4db78.jpg

[Locobob]

https://cimg0.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/600x500-1/80-11b381b7_0244_4790_9e74_503596af4add_1__a6f008b692 fc1747189b859532946d5bc6a4db78.jpg


Now that I think about it I may have done that... looks familiar, I think I may have used my die grinder and a sanding drum and beveled that edge

[Dynomite]

Now that I think about it I may have done that... looks familiar, I think I may have used my die grinder and a sanding drum and beveled that edge

If you did that (used die grinder on interference issue) and the bearing is fine now.......we are back to Phil's suggestion (Fatigue). Or..........."your combination of stuff" rebuilt Tensioner.

It sounds from your description that the Serpentine belt was very loose toward the end which means the pulley was not held tight against the belt. But the pulley could spin freely? Maybe you should go back to the "factory Serpentine Belt Tensioner".

[Locobob]

If you did that (used die grinder on interference issue) and the bearing is fine now.......we are back to Phil's suggestion (Fatigue). Or..........."your combination of stuff" rebuilt Tensioner.

It sounds from your description that the Serpentine belt was very loose toward the end which means the pulley was not held tight against the belt. But the pulley could spin freely? Maybe you should go back to the "factory Serpentine Belt Tensioner".



No the belt was nice and tight, I removed the belt before spinning the pulley. It spins without a load on it but that doesn't mean it would do the same under load. I rebuilt the tensioner about 2 1/2 years ago using the original, some L98 parts, and the aftermarket aluminum pulley. Hopefully that makes it clearer.

[Dynomite]

[/B]]No the belt was nice and tight, I removed the belt before spinning the pulley. It spins without a load on it but that doesn't mean it would do the same under load. I rebuilt the tensioner about 2 1/2 years ago using the original, some L98 parts, and the aftermarket aluminum pulley. Hopefully that makes it clearer.

Hi again:p

When you remove the Aluminum pulley.....
The belt being a bit narrower than the pulley surface.....
See if you can see where the belt track is worn more than the original surface. On aluminum pulleys I have that wear surface is worn less than .005" in about 6,000 miles.

I have no wear on a larger diameter aluminum water pump pulley which also sees the back side of the serpentine belt. When the belt goes around those pulleys the surface of the belt retracts a very small bit wearing the pulleys. I have to check the stock pulleys for similar wear. Or maybe belt slips a bit when starting.

[Locobob]

Got everything apart today, my camber brace makes it kind of a bitch. Here is the worst part of the belt, actually doesn't look terrible.
http://www.zr1.net/forum/picture.php?albumid=432&pictureid=3974

[Locobob]

More pics of the tensioner and pulley
http://www.zr1.net/forum/picture.php?albumid=432&pictureid=3975

[Locobob]

http://www.zr1.net/forum/picture.php?albumid=432&pictureid=3976

[Locobob]

http://www.zr1.net/forum/picture.php?albumid=432&pictureid=3977

[Locobob]

http://www.zr1.net/forum/picture.php?albumid=432&pictureid=3978

[Locobob]

http://www.zr1.net/forum/picture.php?albumid=432&pictureid=3979

[Locobob]

The pulley turns freely and doesn't make any obnoxious sounds, it does feel a bit sloppy however.

[HAWAIIZR-1]

Wow! Thanks for sharing. I did check mine out last week after you posted and it seems okay. I’ll keep an eye on it just in case.


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[BigJohn]

Air Cooled Pulley?

[Dynomite]

Wow! Thanks for sharing. I did check mine out last week after you posted and it seems okay. I’ll keep an eye on it just in case.


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I have some wear on the pulley from the back side of the Serpentine Belt (must be from the belt flexing as it "bends" around the aluminum pulley). It appears the wear on Locobob's pulley is much more as it appears the back side of the Serpentine Belt has worn completely through the Aluminum surface as I can see ridges (Serpentine Belt is a bit narrower than the pulley riding surface between the two guides).

I am replacing ALL Billet Aluminum Belt Tensioner Pulleys with New Stock Belt Tensioner Pulleys immediately. Why wait :D

I am not sure why this pulley wears as it does and the vender says he has seen no issues with this pulley. I can confirm the Backside of the Serpentine Belt does wear on the Aluminum in this application.

How many miles on this failed Belt Tensioner Aluminum Pulley?

[Locobob]

The pulley probably had less than 15k miles on it. I mentioned it to Haibeck and he said he's seen two other failures of the aluminum pulley just like this one. So if you have this pulley you better keep a good eye on it. I have the pulley removed from the tensioner now, still no idea why it failed. It seems to spin about the same as the old Dayco pulley I have laying around - both on the shaft and on my finger, no obvious signs of bearing failure. By the way this "lightweight" aluminum pulley is actually 1oz heavier than the Dayco so there's really no reason to run it other than looks.

[HAWAIIZR-1]

Locobob and Dynomite,

Noted!! I did see my pulley had some wear and I should be concerned too. I don’t have much mileage on mine and probably why minimal wear. I also understand that bearings can behave differently free-spinning with and without load on them.

It seemed like a good idea and nice mod at the time. Maybe just a bad pulley or bearing, but well noted to observe or replace with stock type. I’ll check mine with more detail when I return home. Thanks again for sharing your thoughts and experience.

I guess the moral of the story is to leave sh#t alone!!!


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[Locobob]

Locobob and Dynomite,



I guess the moral of the story is to leave sh#t alone!!!


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Hahaha yeah this isn't the first time the modding disease has bit me in the ***, and it probably won't be the last. I am a little more cautious now about making non stock "improvements" though.

[HAWAIIZR-1]

Hahaha yeah this isn't the first time the modding disease has bit me in the ***, and it probably won't be the last. I am a little more cautious now about making non stock "improvements" though.


Hey Robert,
There are a few of us on here that just won’t leave sh#t alone even if it’s working fine.


9708


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[Dynomite]

Hey Robert,
There are a few of us on here that just won’t leave sh#t alone even if it’s working fine.


9708


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I have decided to replace all of my Aluminum Belt Tensioner Pulleys with New Stock Belt Tensioner Pulleys.
This in spite of the fact that Jim had a Stock Pulley Cut in half by the Serpentine Belt at 60,000 miles :D

I use a ratcheting 18mm Box combination wrench (no angle on ratcheting end and since combination I can use another box wrench on open end for leverage).
I can now replace that Belt Tensioner in 10 min more or less (without removing anything else).
I lift the Belt Tensioner (flipping it 180 deg) up between the Alternator pulley and coolant pipe crossover :p
I use a 14 mm wrench for the Pulley bolt itself.
I do NOT do this job when engine is HOT :sign10:

[HAWAIIZR-1]

I have decided to replace all of my Aluminum Belt Tensioner Pulleys with New Stock Belt Tensioner Pulleys even though Jim had a Stock Pulley Cut in half by the Serpentine Belt :D



So is this the official recall of the aluminum belt tensioner pulleys? LOL!!


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[Dynomite]

So is this the official recall of the aluminum belt tensioner pulleys? LOL!!


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Yes......No recall on Aluminum Water Pump Pulley (which has no Belt Guides and very easy to slip Serpentine Belt off), Aluminum Power Steering pulley, or the Aluminum Alternator Pulley.....Just the Aluminum Belt Tensioner Pulley Recall :D

[HAWAIIZR-1]

Yes......No recall on Aluminum Water Pump Pulley (whcih has no Belt Guides and very easy to slip Serpentine Belt off), Aluminum Power Steering pulley, or the Aluminum Alternator Pulley.....Just the Aluminum Belt Tensioner Pulley Recall :D


Okay, I’ll replace mine at the next opportunity too before the UPR CCC (Cheap Chinese Crap....as they call it in Mustang forums) blows up! LOL!



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[Locobob]

I have a new Gates tensioner pulley and belt installed now. I went off Craigs info on the belt size but I found the Gates 815 belt to be a little loose... like I didn't even have to fight to get it on. So I went one size smaller and found the Gates 810 to be a better fit. This is with SRP underdrive pulleys btw, if you have stock pulleys disregard the belt info.

[HAWAIIZR-1]

I have a new Gates tensioner pulley and belt installed now. I went off Craigs info on the belt size but I found the Gates 815 belt to be a little loose... like I didn't even have to fight to get it on. So I went one size smaller and found the Gates 810 to be a better fit. This is with SRP underdrive pulleys btw, if you have stock pulleys disregard the belt info.

Robert,

Good to hear progress. Sorry if wrong info was given to me years ago when I bought SRP pulleys from Randy. He is straight with info. Be sure your tensioner itself is okay. I still have the cover of the belt I was provided and it was a correct fit. Also double check the part number on the belt itself. Sorry, I'm sure you already know all this. :cheers:

[Locobob]

Robert,

Good to hear progress. Sorry if wrong info was given to me years ago when I bought SRP pulleys from Randy. He is straight with info. Be sure your tensioner itself is okay. I still have the cover of the belt I was provided and it was a correct fit. Also double check the part number on the belt itself. Sorry, I'm sure you already know all this. :cheers:


I don't think its a question of Randys list being wrong. I used a Gates belt that was not on the list based on it being an 815 like the Dayco listed. The last three digits on the belt part number are often the belts length in inches... so 815 should be 81.5 inches. In this case I found the .5in shorter Gates 810 to be a better fit.

[HAWAIIZR-1]

I don't think its a question of Randys list being wrong. I used a Gates belt that was not on the list based on it being an 815 like the Dayco listed. The last three digits on the belt part number are often the belts length in inches... so 815 should be 81.5 inches. In this case I found the .5in shorter Gates 810 to be a better fit.


I agree with you about the numbering system on drive belts and measurement. Glad to hear you got it sorted out and best wishes going forward. I’ll replace mine too before any issues. Thanks again for posting. 🤙🏼



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[2poor4aZR1]

Old thread, but want to say thank you for posting pictures of the back of the tensioner. You'd be surprised how hard it was to find a picture of what the back of the tensioner looks like.