Should i replace the tensioner/pulley also?

[KDehle]

Hello, asking for help for the first time. I have an '06 mega cab 5.9, 4X4, auto' with 90K. I believe I had a "squalling" tensioner a month or so ago. The "squalling" went away, but when I shut down the engine there is a sharp and quick "chirp" which I believe is the serpentine belt coming to a stop. I have a new Gates belt, but think it would be best to also replace the tensioner assembly. Is this thinking correct? Thanks is advance....

 

[GrantP]

I think newer serpentine belts and belt tensioners have similar life spans, I would replace them both at the same time. Did you check the bearings in the tensioner when you replaced the belt? It's good practice to check all of the accessories for rough bearings when doing a belt change.

FWIW, I have never been stranded on the side of the road due to a belt failure but I have been stranded due to a tensioner bearing failure.

 

[seafish]

The chirp might also be the absence of an "overunning" pulley in the alternator that allows some belt movement at shut down. When the serp belt on my 2005 started jumping the grooves while the tuck was under warranty, the dealership not only found and replaced the worn idler/tensioner but also added an overrunning pulley on the alternator as part of a TSB for belts jumping.

 

[Tuesdak]

A 6.7 damper put on as a perk stopped my belt chirp on shutdown w/o the overrun pulley.

 

[KDehle]

Thanks gentlemen...I'll get to work on my research on tensioners/pulleys and checking bearings in particular...

 

[rashwor]

The "chirp" at shutdown is normal on your MY and older. You will know for sure the tensioner assembly is going bad when your belt begins to track to the front of the A/C pulley if you let it go too far. Been there, done that, learned lesson to keep a check on it.

 

[petersonj]

The chirp might also be the absence of an "overunning" pulley in the alternator that allows some belt movement at shut down....

This a good point from Seafish. Also, the truck may already have an OEM overrunning clutch pulley on the alternator and it has failed. In my experience when they fail they will lock up and behave like a solid pulley (possibly the squalling at first and then later the chirp when the engine is shut down). They can make some squealing and other noises while they are in transition from operating normally to full failure.

It seems that overrunning clutches were starting to be used on the 5.9 alternators around late 2006 to early 2007. They are easy to identify - just look for a plastic cover where the nut would normally be on the alternator pulley. You need special tools to replace one.

- John

 

[mwilson]

This a good point from Seafish. Also, the truck may already have an OEM overrunning clutch pulley on the alternator and it has failed. In my experience when they fail they will lock up and behave like a solid pulley (possibly the squalling at first and then later the chirp when the engine is shut down). They can make some squealing and other noises while they are in transition from operating normally to full failure.

It seems that overrunning clutches were starting to be used on the 5.9 alternators around late 2006 to early 2007. They are easy to identify - just look for a plastic cover where the nut would normally be on the alternator pulley. You need special tools to replace one.

- John

My '06 has the over running clutch (ADP) pulley from the factory. I thought that I had a picture but can't find it. It has never chirped when shutting it down.

Mike.

 

[rashwor]

My '05 does not have the factory overrunning pulley and does chirp at shutdown. I had forgotten about the overrun pulley when I first posted.

 

[WalterJ]

My terrible under hood squeal was a new (8 month) NAPA Premium Gates belt, that proved to be too hard to run the flat side upon the fan & pump pulleys. No doubt it would last 100K miles, but my old, albeit softer, spare did the trick. It chirped loudly during shutdown; no over-running AC clutch. Alls quiet now. However...

thank goodness I had installed replacement Crank Vibration Damper p/n #ATI-917374, MANUF # 917374, o.d.=7.8", 3 O-Ring shell designed for easy "rebuilding/repair"; smaller than OEM Dia designed to permit changing serpentine belt without removing damper!

...and we found belt could not be removed past the tensioner pulley without loosening it substantially. What up with that? OEM tensioner replaced 2 yrs ago, so only replacements are goofy or OEM's too?