FAQ: Fragged Tensioner/Idler Pulley Reports & Questions

Series II SC Belt & Pulley Write-Up: https://rivperformance.editboard.com/t725-write-up-replacing-belts-and-pulleys

I knew something wasn't right as I drove the Riv up into the driveway late this afternoon, just didn't sound right. Popped the hood and see a bare SC pulley, and the belt hanging, and the grooved idler pulley gone. All that's left is the bearing and some of the center of the oem plastic pulley. Fortunately there is no damage to the belt, etc, and I have about 15 min before NAPA closes. Hop in the van and run over there, all they have in stock is a plastic Gates replacement, # 38009. For $20, at 5pm on a Sunday, I decided it would do in a pinch and took it.

Didn't have any problem getting the bolt off, and then found that the bearing had locked up, besides the plastic breaking. Actually I wouldn't be surprised if the pulley was fine until the bearing locked up.

While the oem pulley lasted 116k, I'm not pleased NAPA didn't have a metal 89051, and will try to track one down locally this week and swap again.

Sorry to hear about that, Dave.

I only use plastic grooved idlers. Have had no problems so far for tens of thousands of miles. I like them because they're light and inexpensive; there's no reason the bearings in a plastic pulley can't be as good as a metal one.

I didn't know the grooved ones came in metal. I suppose Aaron is right and it's not as critical to get the grooved ones in metal as it is with the smooth ones. The ribs probably add enough strength to keep them from fragmenting the way the plastic ones do. When I changed my plastic pulleys I noticed about half the material had worn off the smooth ones - definitely don't want that again!

Well, it IS hard to say the plastic pulleys aren't any good. After all, the oem pulley lasted 116k. Unfortunately I can't read the country of origin on the oem bearing, but the new Gates says Made in USA on the box, but the bearing itself is made in China. I wanted metal, since it is strongly suggested in the write-up on belts & pullies, including this pulley.

I suspect my oem pulley was just fine until the bearing froze up. Aaron, I agree on the concept of the lighter plastic, and may just go with this Gates unit if the 89051 is on the expensive side.

The metal Dayco pulley is only $16 from Rockauto, about 5 bucks more than the plastic from Rockauto. NAPA sure didn't give me a deal, at $20, compared to $11. But at least they had it on the shelf. Wish I'd had time to check a couple other parts stores, but they all close at 5 on Sundays.

NAPA makes it sound like this pulley(38009) is as good as it gets:

Features & Benefits:Meets & Exceeds OE Specifications. High Quality
High Strength Bearings Run Cooler. Last Ten Times Longer than Original Bearings. Steel & Glass Reinforced Polymer Pulleys Built to Last
Resist Dirt
O.D.:76mm
Width:25mm
Material:Thermoplastic
Contact Surface Type:V-Ribbed Grooved
Additional Contents:Thermoplastic V-Ribbed 6 Grooved (76mm x 17mm x 25mm)

I think there's a built in archetype in all of us that says, "metal is better than plastic". But there are times when it's clearly not. If they were made from titanium, I could see that, but who wants to pay $200-300 for an idler pulley?

The upg. plastic part is probably as good as the metal one. Both are an improvement over the stock design.

And in the end, I think the failures are more likely to be in the bearing anyway, not the pulley body. At a claimed 10 times the OEM life, I'll stick with the new plastic one already installed.

The best part about this story is, your belt is still good. $20 and 15 mins to fix, and you're good for at least another 100k.

For sure, I'd have been pretty PO'd if the belt was destroyed, in our current weather situation, and no heat in the garage.

My understanding is that the GATES plastic pulleys are pretty durable, and can be thought of as a "once and done" replacement.

Albertj

I've used both and agree about our mentallity about the metal vs plastic.

Next time you hit up Napa..pull out the AAA card and get yourself 7% off. It's a little known discount.

What? You're kidding me! I pay AAA $80/year, and never use them. And I shop exclusively at NAPA!!!!!!!!!! (posting in Information)

No AAA card here currently, but thanks for the tip.

Ask for a discount..

Worst case, you'll pay full price.

Always do.

My original grooved plastic pulley had chips on the grooves... it made go with the metal one... I think that might have also had something to do with my recent belt failure.

AA wrote:

The best part about this story is, your belt is still good. $20 and 15 mins to fix, and you're good for at least another 100k.

Looks like I'll be doing belts after all...

Checked underhood at noon, and the SC belt is coming apart. Likely my own fault too. I recall after installing the new idler pulley, the belt was riding a bit farther to the outside edge on the smooth tensioner pulley. But it wasn't off the edge of the pulley and looked ok otherwise, so I didn't worry about it. But when I looked down closer at the crank pulley at noon, the belt looked like it was off one rib to the outside. That outside rib on the belt is what's pulling apart now. Crap. So I took the belt off the tensioner and realigned things properly, and will see if it will hold up for a bit longer.

We might see near 30deg this weekend, but I'm not sure that's the conditions I want to do this under. If the belt deteriorates quickly, I'll just cut it off and run w/o the SC til it's warm enough to spend an afternoon on this project. Also looked closely at the plastic lower smooth idler pulley, and it's just about junk. Stopped at NAPA and got the Gates x-reference to the Dayco metal 89006 pulley, which is a 38001. Should be fun replacing that one, judging by write-ups.

Ugh... Dave, that's really too bad. I've read more than a few cases where someone has done the exact same thing. I've done it myself at least twice. I don't even trust my eyes any more. Just reach down and feel the edge of the crank pulley.

I think the problem was that I first lined up the belt on the backside on the crank pulley, instead of making sure the front was aligned, and the belt is pulled in from the front. Off at the front, the belt ends up off all around the pulley.

I've seen it a lot of times as well. I reach down and feel each belt and each pulley after getting either of the belts on. (Especially after tossing a belt or two at start up )

The odd thing is that I started it up and watched the belt tracking for a minute to ensure that it was aligned correctly. Guess I should have shined a light down on the crank pulley, it was likely off a rib there as soon as it turned over, just couldn't tell up top until the belt damage became obvious.

I drove about 15 miles yesterday afternoon with the belt on properly, and it seems it is holding up ok for now. Maybe it'll survive till we warm up some.

My old grand am I had still drives to this day on a 6rib gatorback belt thats been a 4rib since 2003. A motor mount bracket was missing an important bolt so it shifted over for the belt to rub on until I could find it. I was waiting for it to fail but it never did. No noise, no slip.

The belt will last a surprisingly long time with 5 ribs... but it really sucks if it lets go unexpectedly.

At least it's just the SC belt, you just lose some power and save some gas if the belt lets go...