Tensioner pulley bit the big one

[mn911girl]

My husband and I have a 1999 Explorer Eddie Bauer v8. The tensioner pulley burnt to a crisp last night, luckily he was close to home. We're attempting to figure out whether or not the pulley is smooth or grooved... everything I find online is for a v6, which is not helping us answer that question. And depending on which online merchant I find, one is just the pulley, and the other has an attachment at the back... Help??

 

[974X4BLACKSPORT]

I have always found that the tensioners are metal pulleys with smooth surface, this is because it applies pressure to the back of the belt to provide the "tension" needed to traction. Idler pulleys are grooved to guide the belt in direction change, and are usually plastic. Some idler pulleys are flat if they ride along the back of the belt, and grooved pulleys are always plastic, and the grooves are to guide the belt.
I think in your case you will be looking for a metal tensioner pulley with a flat surface. I looks like your damaged on was plastic! Are you sure that is the "tensioner" or an "idler" pulley?

 

[fast_dave]

My husband and I have a 1999 Explorer Eddie Bauer v8.

@mn911girl

When I put your Ex's data into Rock Auto's Excellent & Accurate Online Catalog, here's what I find (via the pictures):

* Every Belt Tensioner Assembly (Tensioner & Tensioner Pulley)
&
Belt Tensioner Pulley (the Pulley offered with out the Spring Tensioner Assembly)
is made of Steel and is Not Grooved.

*As far as the Belt Idler Pulleys offered, there are ones made of Steel with a Smooth Finish,
&
ones made of Plastic with a Grooved Surface.

What you have pictured, that is burned up, is a Belt Idler Pulley that is made of Plastic - which means it's grooved.

Hope that helps, welcome to the forum, and here's a 5% Rock Auto Discount Code
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[mn911girl]

I believe you are right. On the diagram, it would be a grooved pulley. Thank you!

 

[fast_dave]

I believe you are right. On the diagram, it would be a grooved pulley. Thank you!

@mn911girl

If the bearing went bad and locked up in the Idler Pulley, causing it to burn up, chances are that the bearing will soon go bad and lock up in the Tensioner Assembly.

BUT - all you need to buy is the replacement Tensioner Pulley. Might as well replace it now. I have 215,000 miles on my factory original Made in USA Belt Tensioner Assembly - it's built like a TANK, and have changed just the pulley three times as a maintenance item with the Gates replacement pulley. Aftermarket Belt Tensioner assemblies are made in China, and the Motorcraft offering is made in Mexico. Your mileage may vary.

In closing, it goes without saying that you need a new belt ;-)

 

[koda2000]

If I were you (and if you've never replaced any of the idler or tensioner pulley's) I would replace them all and also replace the the tension itself and belt. If one pulley locked up they're all near or at their service life. Also inspect the A/C clutch pulley bearing while the belt is off.

 

[BUXTER]

The Lower Grooved IDLER Pulley on my 2001 Merc 5.0 is UNDER the Tensioner - OEM was steel - Replacement was Plastic - & Yes like a dumbass I put Socket & Ratchet on the Tensioner Pulley Fastener to de-tension the Tensioner & install Belt & I stripped out my brand new Tensioner Pulley Threads - SO>>> I put new Pulley on old Tensioner (only 77K miles) & reinstalled old one but used a block of wood between Tensioner & Harmonic Balancer to de-tension tensioner for Belt install - & Yes the Upper Idler Pulley is smooth Steel as it rides on back of Belt per prior Posts.

 

[koda2000]

The Lower Grooved IDLER Pulley on my 2001 Merc 5.0 is UNDER the Tensioner - OEM was steel - Replacement was Plastic - & Yes like a dumbass I put Socket & Ratchet on the Tensioner Pulley Fastener to de-tension the Tensioner & install Belt & I stripped out my brand new Tensioner Pulley Threads - SO>>> I put new Pulley on old Tensioner (only 77K miles) & reinstalled old one but used a block of wood between Tensioner & Harmonic Balancer to de-tension tensioner for Belt install - & Yes the Upper Idler Pulley is smooth Steel as it rides on back of Belt per prior Posts.

I've seen metal pulleys with a ridge on both edges (cast and machined maybe?) but most all ribbed pulleys are plastic. The issue isn't the plastic material melting, it's the bearing wearing out and getting so hot that it melts the plastic pulley. Either way, when the bearing goes you're going to have a problem.

Most tensioners have a square 3/8's" hole in them to put a 3/8's ratchet, or breaker bar, in to release the spring tension. Sometimes the location of the hole is not convenient (easy to get to) and I've used a wrench on the pulley bolt many times without any issues. I find the 5.0 belt tensioners are harder to release than the 4.0L's.

A tool like the one pictured below can be helpful in replacing serpentine belts, but I've never found the need to go buy one.

 

[BUXTER]

I have SEVERAL 4.6 V8's & 5.4 V8 & ALL have the hole for 3/8 Breaker Bar in Tensioner Arm - My OEM & Napa 5.0 Tensioner Pulley Assemblies had no such hole - BTW the Modular motor Tensioners are harder to de-Tension than the 5.0 IMO.