Failed tensioner pully pics

jbhebert · February 2, 2007

Recently, I noticed belt noise coming from my '94 Explorer V6 with about 178,000 miles. Shortly thereafter, I started hearing a scarier noise - the fan contacting something as it spun. I shut the truck down and investigated and found that the tensioner arm assembly had failed at the pivot point and was backing out into the fan:

You can see the nicks on the fan blades where they made contact. You can also see how ****ed the tensioner is relative to the other accessory pulleys:

I removed the belt and the tensioner assembly litteraly fell apart. The tension of the spring against the belt that was all that was keeing it together. Here are the parts of the old assembly:

jbhebert · February 2, 2007

New tensioner assembly

The new assembly was less than $40 from the local McParts place. It included a new pulley and a redesigned tension spring. I didn't take it apart, but it appears that if the new assembly were to fail, it would at least stay together, but I can't say for sure. Here's the new unit:

Note the flat "clock" style spring (you can see the hooked end sticking out) versus the coil spring from the OEM unit.

All told, it took about 20 minutes (including pauses for pictures) to swap in the new tensioner. One bolt holds it in; simply remove the bolt, remove the old unit, install the new unit making sure that the key on the engine locates in the slot on the tensioner. There is a 3/8" square hole in the tensioner that allows you to preload it with a socket or breaker bar to install the new belt - I got a new belt, since I couldn't remember when it was last replaced and I was already in there.

Anyways, the point of this post was primarily to alert you all to this potential problem. Next time you're under the hood, take a peek at the tensioner and make sure it isn't starting to go.

DeRocha · February 2, 2007

Thank you for the post and pics.. :thumbsup:

CBII · February 3, 2007

Hmmm I noticed a belt noise under the hood the other day. After seeing your pics I think I might replace the tensioner before if causes me more problems. :thumbsup:

MadScotsMan · February 3, 2007

I just replaced (Monday) two tensioner pulleys, belt and fan as as result of the upper pully going "boom." It only squealed one time, several days before, and then it disassembled itself in a rather spectacular fashion, leaving me stranded in Starksboro, VT.

ExploringNC · February 5, 2007

Thanks for the post. I am needing to replace mine(has a rattle noise) but I wasn't sure on the dificulty or the price. Thanks

Tony H · February 5, 2007

this new style tensioner takes one bolt? the OEM is two and one of the bolts is behind the pulley making it tough to get off. Is that correct?

I also like the 1/2" drive approach to loosen the belt tension as opposed to the OEM 'grab the pulley bolt'

jbhebert · February 5, 2007

Tony H said:
this new style tensioner takes one bolt? the OEM is two and one of the bolts is behind the pulley making it tough to get off. Is that correct?

I also like the 1/2" drive approach to loosen the belt tension as opposed to the OEM 'grab the pulley bolt'

Both the old and new style use just one bolt to attach to the motor. The other bolt holds the pulley on.

J.B.

Dave Reynolds · February 5, 2007

Yes, I ignored the warning sounds. And while on the way to work one day I watched the various parts bouncing down the road in my mirrors.

Hopefully the new unit stays together.

shamaal · February 5, 2007

I too, kept putting in off. Then it seized and broke the belt. The belt then wrapped itself around the waterpump shaft and physically broke it.

And I knew better.

StillKicken · February 6, 2007

What did it sound like? I heard this whistle sound coming from the front of engine, thought was water pump. Replaced that and checked tensioner while in there and had belt off. Seemed fine. New water pump, but sound still is heard. Only at start up though.

Ranger379 · February 6, 2007

i reaplced both tensioners on both of our explorers in the same week, noticed mine was sqeeking and looked and seen mine was ****ed back and reaplced it and all was good, looked at the one on the 95 later that week it was same way but not making noise yet, replaced it too, 50 bucks from local ford dealer. easy job tho, glad mine wasnt hitting fan blade, i think your lucky u caught it in time before it fell apart and broke your fan...

agobbie · February 6, 2007

That happened to me on a94 Grand Prix -- Exactly the same thing !

dubs66 · February 8, 2007

Just wanna say thanks to all involed with this thread. It really saved my ass today. I had to change the tensioner assembly and the idler. Thank god the car was only at a very slow speed then the idler let loose and went flying. I figured as long as I have to do the idler that I might as well do the tensioner assembly to and i'm glad i did because it to was seized up and would have probably came loose too. So if your gonna do this job you may as well do both just to be on the safe side!!! I kinda knew this was comming because there was some pretty strange noises comming from the belt but it's been so cold out here in WI. that I just ignored it as much as possible (turning up the radio seemed to fix it) LOL Thanks again guys.

Hokie · February 8, 2007

When the bearing seized on my tensioner pulley it actually spun, twisted and melted the plastic pulley off of the part where it mates to the bearing. Kinda cool - except that it cost me $40 to get my truck towed back to my apt and away from the highway.

I needed to change the serpentine belt... so that was a good excuse :thumbsup:

lol

killswitchfan134 · February 28, 2008

i just replaced mine and it didnt even take 20 mins I'm glad i saw it before it completely fell apart and destroyed something under the hood

410Fortune · February 28, 2008

You can usually get away with just replacing the bearing on the pulley when it starts to grind, less then $5 this will save the spring loaded tensioner assembly 99% of the time.

Autozone has the pulley with bearing for under $20 I believe

I have a collection of pullies these days, V6, V8, Gen I, II etc its kind of sad really.....

96eb96 · February 28, 2008

Just FYI: If you dont change your upper idler pulley its going to go sooner or later. You won't get warnings until its way too late. Don't put this off unless you want to be stranded in some random location. I know 5 cases personally and many more from messageboards. If you didn't already change it do it tomorrow. I keep a spare in my glovebox after what happened.

410Fortune · February 28, 2008

I replaced a 4.0L OHV engine for a friend after he was driving through WY in the middle of the night when his idler pulley let go, he's not very mechanical so he kept driving as far as he could to the next town. By that time the engine was fubared (overheat severe). $400 tow home, $500 to me for labor and $400 junk yard engine...

thats one expensive pulley!

metalmechanic · February 28, 2008

Must be the weather!

Cuz both my idler pulley bearing and tensioner assembly have failed in the last two weeks as well.:thumbdwn:

Failed tensioner pully pics

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