Serpentine belt and pulley broken - need advice

CMullin · **Joined:** Tue Oct 20, 2015 10:58 am **Posts:** 19

My 2005 Jeep Liberty CRD has had issues with the serpentine belt a few times now. It was replaced last year due to a squeal and had started squealing again about two months ago. I brought it into a shop and let them know I thought a pulley needed to be replaced but they just replaced the serpentine belt again and said they checked the pulleys and that they were ok (not sure if they actually checked them or not). Anyway, the squeal came back a few days later and then the new belt shredded a piece off the edge and fell off this weekend when the jeep was idling. I replaced the belt again myself on the road and the noise changed from a squeal to a clicking noise coming from one of the pulleys on the left side (tensioner or one near it). I tried driving it home regardless of that noise but the new belt shredded up on the way back. I think the issue is the tensioner pulley or the one above it.

From what I have described, does anyone know if I should now just try replacing the tensioner pulley and the serpentine belt, or do you think it could be another pulley? How might I be able to tell which pulley is causing the problem?

Any advice would be appreciated. Thank you!

BlueLghtning · **Posted:** Mon Feb 29, 2016 2:12 pm

I know it's not the same vehicle, but I kept shredding belts on my VW Beetle TDI and it ended up being both the tensioner and idle pulleys needing to be replaced. No issues since then after going through quite a few belts in short order.

WWDiesel · **Posted:** Mon Feb 29, 2016 2:42 pm

Could be the tension pulley, idler pulley, or the override pulley on the alternator. Remove the serpentine belt and turn/feel each pulley by hand and feel for any abnormal resistance and listen for any unusual noise... All should turn freely except the crankshaft pulley... :wink:

papaindigo · **Posted:** Mon Feb 29, 2016 2:50 pm

If you have not already done so read Sir Sam's NOOB guide.

While it's not impossible that the root cause is something else the most likely cause is a bad decoupler (OAD) pulley on your alternator. When that pulley goes bad it also has a tendency to destroy your serpentine belt tensioner. If you had the serp belt on the engine then I'd say at idle look down past the air filter box at the serp belt tensioner - if it's doing anything more than barely twitching then the decoupler is likely shot. Absent the serp belt being on the engine a) look at the tensioner - if it's leaning into the power steering pulley then the tensioner is shot and b) pop the plastic cap off the decoupler - if there is lots of red dust the decoupler is shot. A good replacement decoupler pulley is Litens 920834, it's grease filled, recommended by Litens, and a bit smaller in diameter than OEM but not enough to matter. Removal requires a special tool which can be fabricated see viewtopic.php?f=5&t=75841&p=796353&hilit=alternator#p796353 or purchased Lisle tool kit LS57650.

If the body of the tensioner is ok but its pulley is shot then the pulley can be replaced. That pulley and the 2 serp belt idler pulleys are all the same and can be obtained at a local parts store - NAPA 36101 (just lose the big washer) or Precision Parts EP101 or you can remove and replace just the bearing part of the pulley see viewtopic.php?f=5&t=76128

The bolts holding the idler pulleys can be unscrewed CLOCKWISE. I'd pull them and look at the back, if leaking grease then replace.

CMullin · **Joined:** Tue Oct 20, 2015 10:58 am **Posts:** 19

This all has been very helpful. After spinning all of the pulleys and checking them for extra movement back and forth I've found a few issues.

The decoupler (OAD) pulley has a very distinct wobble that looks exactly like the one in this video I just found on youtube (https://www.youtube.com/watch?v=y_Ots4QHybs). I will plan on replacing this first.

The tensioner pulley seems to have to much back and forth movement (makes a clicking sound). The pulley just above the tensioner and to the right (not sure which this is) also feels loose and slightly moves back and forth. I took a video of this to explain but can't figure out how to attach it to this feed. I'm not sure if these two pulleys should also be replaced in addition to the decoupler.

Additionally, pieces of the last serpentine belt are melted onto the pulleys and a slice got stuck around part of the tensioner pulley making it harder to spin. I pulled out all the parts I could but there is still some resistance. Is this going to be an issue if I replace the other parts and the belt and then run it? Also what should I use to clean the leftover belt off the groves of the whole system?

papaindigo · **Posted:** Mon Feb 29, 2016 4:37 pm

Comments:
1. I looked at the video and that decoupler is shot based on the red dust. I suspect the wobble is just part of the decoupler failure but it's not impossible it's from a bent shaft in the alternator itself.
2. like I said the tensioner pulley can be replaced but given your shredded belts if it was mine I'd get a new/used tensioner as a replacement. idParts has a new one for ca. $160 but you might ask the "group" if someone has a good used one as several folks have vehicles they are parting out.
3. if by pulley up and to the right you mean the small smooth surface one next to the engine lift hook and up and left of the fan mount pulley then that's an idler pulley. As cheap as the NAPA part is I'd just replace both idler pulleys.
4. anything that causes resistance to pulley rotation is BAD and not to be run that way. If you replace the tensioner that problem goes away. If the surfaces that have bits of belt stuck to them are metal you can remove the bits of belt with simple tools like wire brush, narrow blade screw driver, etc.

Once you get it back together. Before cranking up look at the whole system to make sure things are lined up. After cranking up before driving at idle check to see if the tensioner is barely twitching and that the belt is running straight and true.

CMullin · **Joined:** Tue Oct 20, 2015 10:58 am **Posts:** 19

Just to verify I have this all right....

1. I will replace the decoupler pulley (A). On mine there is some red dust (not as much as the video I posted) but the wobble is the same. While doing this, is there a way I can check to find out if there is a bent shaft in the alternator itself?

2. C in the image I just attached is the tensioner pulley that wiggles a little too much. I should just replace the whole tension unit there.

3. B in the image is a little loose as well. This is one of the idler pulleys and I will plan on replacing this.

4. D in the image. What pulley is this? This is the one with part of the old belt stuck in it. I had checked this recently (before the second break) and it turned smoothly now doesn't because of that rubber stuck in there. Should I just it off and pull that rubber out and put it back on. This pulley is not part of the tensioner correct?

thermorex · **Posted:** Mon Feb 29, 2016 5:14 pm

D is power steering pulley. You may need to replace the pulley under a, which is also an idler pulley. Keep in mind that idler pulleys are un bolting as you would torque a normal bolt (left hand thread).

Oh, I think you need to take it out anyway, to replace the tensioner.

Make sure you get the updated alternator pulley, Litens PN 920834, available at advance auto or online.

papaindigo · **Posted:** Mon Feb 29, 2016 5:30 pm

Ok:
A = alternator decoupler pulley - replace. Note a local auto electric place may do this rather inexpensively if you bring the alternator too them. Not hard to remove; just 4 bolts. If no wobble with new pulley alternator shaft is ok; extremely unlikely it's bent or otherwise shot.
B = idler pulley - replace. And as thermorex notes replace idler pulley directly below alternator decoupler pulley. Bolts (16mm) unscrew clockwise and should only be tightened snug not godzilla
C = serp belt tensioner - as previously mentioned replace with new or good used. Held on by 13mm bolt left of pulley.
D = power steering pulley - 3 10mm bolts, hold with long 10mm socket thru hole on right side of pulley if needed. Clean belt junk while off engine. Yes this has to come off to get tensioner off.

Serpentine belt and pulley broken - need advice

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