How-To: Test 2.3L Turbo Engine Serpentine Belt Pulleys

C.T.B.B.

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07 Speed3
My 07 MS3 has been making a little racket under the hood the last week or two, finally addressed it today. I knew the serpentine belt tensioner pulley bearing was making some noise, sounded like a pop can full of rocks down there if you pressed one end of a stick on the pulley retaining bolt and the other to your ear, was fairly noticeable even with the hood closed at idle. Called my local Mazda dealer who informed me it was not covered under the 60K engine warranty, though I didn't think it would be. Transferred over to parts, pulley is not sold separately from the tensioner, bearing is of course not sold separately from the puller, the tensioner was like $144.00 I think, may have been cost, maybe list, may have been another call I, and not only not in stock, but on national back order with a waiting list of 173 units. Mr Parts Man thought it would be months before he could get one. Mind you, this is a smaller dealer in a town of 15,000 and not a Speed authorized dealer, but I don't believe that would change their ability to order parts for others.

Called the local NAPA and Auto Value stores, nothing listed in catalogs/computers for tensioner or replacement pulley. I knew that my tensioner bearing wasn't going to get me through a few months so my options were shrinking. Pulled the pulley off the tensioner and measured it, 70mm O.D. x 17mm I.D. x 23 mm wide. Checked Dayco buyers guide, guess what the dimensions are for their 89015 pulley? :) Had it in stock at local Auto Value, number should be easy to cross by any supplier and fits a bunch of other common vehicles, my cost was $14.14 but don't be surprised to pay 18 or 24 or something similar retail. Exact match to OE pulley size wise, just has differently designed support webbing on the plastic portion. Problem solved, except...

Did general check when the belt was off, found the idler pulley had a lot more side to side play than I liked, pulled it and sure enough, bearing is crapping out there too, felt rough spinning in your fingers but wasn't making noise that I knew of, or else had been masked by the noise from the tensioner pulley bearing. NAPA had a listing for the idler pulley at $55.29 but not in stock, and a heck of a lot more than I wanted to pay and I really wanted to get the job done when it was already apart. Pulley wasn't really bad, the bearing was, so cross referenced the number stamped on the bearing, it crossed to a National 203FF, local Auto Value had three of them in stock at cost of $2.97. Pressed out old bearing, pressed in new, perfect fit. Again, don't be surprised to pay a little more retail. NAPA shows 4 different bearing numbers for that cross, all showing different applications and pricing, from $3.29 to $14.99 list.

I never asked Mazda what the price was on the idler or if they had it in stock, but with the price of the tensioner pushing $150 I wouldn't be surprised if the idler is $30 or 40, I figure I got conservatively $160 worth of parts replaced/corrected today for under 20 bucks with no wait for delivery and numbers that should be readily available anywhere. It's a very straightforward job when the car is on a hoist, maybe 30 minutes if you take your time, after doing a couple could probably be done in 10 or less. Tensioner is accessible from right front wheel well with inside splash shield removed, idler not staring you in the face from there but still pretty easy to reach.

Be careful. With the engine running, take a long screwdriver, wooden dowel, what have you, and stick it down alongside the serpentine belt and onto the retaining bolts of the tensioner and idler. Put the other end on the very front of your ear, against the side of your cheek, and listen for the growl. If you're not coordinated enough to do this without hurting yourself, don't attempt it. It could slice off your head in two pieces like a Magic Ginsu Knife and never think twice. Seriously. That screwdriver getting grabbed by the spinning belt will smack you in the face harder than Mike Tyson after you stole his George Foreman Grill. If the noise you're hearing from the engine is in sync with and sounds like that growl noise, grab a couple wrenches (I believe was a 12 mm for tensioner and 10 mm for idler) and a seat and fix em yourself.

Tensioner Pulley: Dayco #89015
Idler Bearing: National #203FF


*If I would have been really on top of it I would have checked the number for the bearing for the tensioner pulley and replaced it instead of the entire pulley, if it's not gone I'll check that number on Monday, probably easier still to find the bearing than the pulley.
 
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It's really difficult to tell if your noise is from the idler or tensioner bearings from the video, but if it's coming from the belt area it very well could be. Try the screwdriver trick to the ear, but be careful so as to not get your head sliced off. Very bad ju-ju. Glad I could be of some help, just returning the help I've gotten from the board.
 
Just trying to help out where I have something to share.

Liquidflem, you get yours put in today? How'd it go? Did it fix the noise?
 
Just trying to help out where I have something to share.

Liquidflem, you get yours put in today? How'd it go? Did it fix the noise?

I haven't gotten a chance to put it in yet, but i will definitely let you guys know how it works out when i do. Tomorrow most likely.
 
Sticky this thread!!!!!!

This thread needs to be stickied somewhere. Anything that can save an owner this much money on repair costs should be saved where it can be easily found.
 
This thread needs to be stickied somewhere. Anything that can save an owner this much money on repair costs should be saved where it can be easily found.

Agree. Mods, can you "sticky" this up for all of us. Great info, OP. This is something we will all need to know, sooner or later. Thanks.
 
Just an update regarding the bearing on the tensioner pulley...

Found the old pulley, dug it out of the trash, but found it. The idler pulley is metal, pressing bearing in and out pretty straight forward. The tensioner pulley is plastic. Not so straight forward. Short and simple, the bearing is held in with "X" amount of tension, but to overcome that tension and press out the bearing requires more force than the plastic pulley can withstand and the pulley shatters. I suppose if you were on a very tight budget and set up the press very carefully it could be done, but as inexpensive as the entire pulley is, hardly worth the hassle. They do make things easy though, the same bearing is used for both the tensioner pulley and the idler pulley, the 203FF.

Thanks again for positive comments.
 
Rut Roh.. my bad....

Just inspected the tensioner pulley a little closer after my last post, the pulley is molded around and encompasses the outermost edge of the bearing so any attempt at removal will result in destruction of the pulley, regardless of how carefully you set up the press.

And Thank You for making this a sticky, I feel like I'm somebody! :)
 
Is there a better way to listen for that growl noise without the risk of getting your head chopped off?
 
Nope, that's the only option, live fast, die young. (nailbyt)

Actually, you can probably access the bolt for the tensioner pulley from the right inner fender, but my car is out getting the windows tinted today so I can't verify that. I will, however, check it tomorrow. Should be able to put the screwdriver tip on it from there and listen without having to snake it alongside the spinning belt.

No harder than it is really, you could just pull the pulleys off, hold the pulley by the center bearing hole between your thumb tip and index finger tip and spin the pulley. If it growls at you, replace it. I can't explain how to know when the bearing is making noises it shouldn't, that's one of those experience things you just have to learn over time.
 
Rut Roh.. my bad....

Just inspected the tensioner pulley a little closer after my last post, the pulley is molded around and encompasses the outermost edge of the bearing so any attempt at removal will result in destruction of the pulley, regardless of how carefully you set up the press.

And Thank You for making this a sticky, I feel like I'm somebody! :)

Could you replace it with a metal one by matching it much like you did with the idler pulley?
 
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