I realize it is self tightening, but is there a possibility that they "lose" their "strenghth" to keep the tension, and may need adjusting? My chirpping noise that I've been chasing down for almost 2 years seems to be getting worse, and more frequent. The FSM mentions that a fix for this maybe tightening the automatic tensioner, but i do not see a "how to" anywhere. Here is what I have checked so far in diagnosing this noise:
1. Possible head gasket failure: can't be. All fluids are proper in color and smell.
2. Power steering pump. Brand new, 6 month old NAPA
3. Turbo: No problems there. This is a hybrid from PDR which is 2 years old.
4. Loose hardware: none found, so far.
5. Belt: brand new Cummins brand.
6. Water pump: Brand new, NAPA
7. Valves: Adjusted religiously, usually before every 12,000 miles.

That leaves, I believe, either the belt tensioner, or possibly the alternator? Does an alternator have bearings that could start going bad? Sorry for the mix in questions. I tried the search feature on alternators, and so far they relate mostly to electrical charging problems. Please advise.

 

Belt tensioner is known problem at times. They usually go bad at the pivot point on the tensioning spring. You'll look at the pulley and notice the belt isn't riding in the center of it. As the pivot wears, the belt gets closer and closer to the arm, eventually touching it. If it gets to this point you'll start eating belts and the belt will start cutting into the aluminum arm. Easy to replace. And I think around $50. Available at Napa.

 

Last week i had a curping noise when the truck was running, it turned out to be my Belt Tensiner pulley starting to lock up, you could see the tensionr jumpping alittle bit. Of cours Napa didn't have one in stock (less then $30) and it would take a few days and i needed the truck, so i bought the whole tensionor set up ($130) since they had it in stock, no more churping sound.

 

I'll look into this, and as always, thanks for the replies.

 

Just a thought but you might want to check your A/C clutch too.

 

My understanding is that this item is a standard wear replacement. After a 100,000 or so its time to replace and while your at it the water pump should get replaced not expensive and is a good idea unless you like the smell of leaking anti freeze.

 

Y'all correct me if I'm wrong, but I believe the "Chirping" is actually when the engine initially comes to a stop. It actually rocks backward in rotation, then forward again [due to cylinder compression(s)]. This can happen in rapid succession till the thing finally settles down.

The whole while, things like the water pump, with the fan clutch possibly engaged, as well as the alternator, etc, try to keep pace with the rocking belt.

The alternator's rotor for example, has some good mass to it. It takes some torque to twist it back and forth like that.

If there's not enough tension on the belt, or, it's grip ability has been lessened, something's gonna Chirp about it (belt slipping).


IMO, it's no big deal. If the belt's tight enough to spin the water pump, fan, and alternator, all at their rated loads without slipping, all is well.

Tightening things beyond that point introduces excessive bearing loads thus shortening their life.

It's a balancing act.

Hope this helps.

 

I'd lean toward the alternator. I'm pretty sure that's where my chirp is coming from...I'm assuming you're meaning a chirp at idle--especially when the engine is cold and it's damp out? That's when mine's the worst, but it's an equal opportunity pain in my butt, so it'll do it just about whenever, if it takes a notion I have a new tensioner and the sound is the same, as is the tension. Remove belt, fire the truck up, no noise. Oh, when my factory tensioner went, I was winding it up in 4th and it was like a nitrous hit--those accessories pull at least 50rwhp. Here's how mine ended up...not sure how it melted like that while running and stayed in one piece....

 

Ouch!...............10 characters

 

yeah, I had more than 10 characters to say when it happened I drove normal (60mph) for almost 5 miles before the temp started to go up and I realized where my extra power came from

 

I'll bet! Things that go bump make me want to carry a parts store in my truck box. Trouble is, there ain't enough room in the box or the wallet. Glad I got a garage and lots of friends.

 

Minimal impact carnage - love it. But I hate it when stuff actually comes apart and destroys everything nearby resulting in high-buck repairs.

 

sounds like for the cost of a NAPA tensioner, It wouldn't break me to just replace it(hopefully still $30!!) I checked the tension of the belt on my chirping truck against another '93 and the chirping truck belt is slightly less tight than the non chirper, or better words, has more slack. Wish me luck on this problem being resolved. I'll let you all know. Thanks, guys.

 

Oh, before I forget. Any part #'s for the tensioner?

 

Usually, after many years, the spring in the tensioner gets fatigued
and the tension value will decrese. I put on a new tensioner on my truck
and the chirp stopped.