Serpentine belt slipping

[bort]

Hey guys, So a couple of days ago the serpentine belt decided to slip off and was cut enough to become unusable. I was told my idler pulleys and belt tensioner were loose so I bought and replaced everything myself with the help from some of the other threads I read on here. I put the new belt on but when I start the car the belt moves forward and hangs half way off the bottom idler pulley and eventually slips off. Im guessing something is misaligned but I'm not sure what it could be.

 

[NeddyBear]

Sounds strange, did you replace all the idler pulleys and the belt tensioner with new unused items.
I couldn't imagine what would be misaligned or why the belt came off the start with.
What kind of timeframe was the belt last repalced.

 

[acarmody]

Grab the air-con compressor by the pulley and try moving it. I had one of the compressor bolts shear off and let it move around ruining the alignment of the belt and keep ripping it apart. Not fun losing power steering and coolant in peak hour traffic at speed in the far right lane.

 

[Brett_jjj]

Is the A/C compressor still fitted? If the A/C compressor has been removed, the bottom idler pulley and its mounting have to be removed. Are you refitting the belt the correct way?

 

[wortus]

Have you got correctly paired idler pulley's and serpentine belt? I am sue there are slightly different diameter pulley's and length belts as running changes from VT onwards, perhaps the replacement parts are mismatched making the belt a bit loose?

 

[wildfire40]

VS V6 Serpentine Belt riding forward on belt tensioner pulley

Hi Guys,
I have recently had problems with my Serpentine Belt riding forward on my Belt Tensioner pulley to such a degree that it was partial off it. The belt had slipped off and disintegrated itself once , so I decided to replace the tensioner itself with a new one. Put it all back together and it was exactly the same.
I have read heaps of items on here about similar situations but never any fixes for it. Well I have fixed the problem and will share what it was and how to check if it is the same problem in your situation.
What fixed the problem was replacing the Harmonic Balancer. This was on a VS V6 with 250,00km but would be the same on most of the V6 Ecotec Engines that followed. If you are experiencing a similar problem, here is what to look for.
Looking down at the idler pulley between the Harmonic Balancer and the Air Conditioner pulley ( bottom & right of the harmonic balancer) you should see the belt is running forward slightly on that pulley. You should see the shiny part slightly exposed where the belt was normally running beforehand and is now moved forward slightly. It could be as little as 1 to 2mm, it was in my case. This amount of movement will show up at the tensioner pulley as being around 6 to 8mm out.
The result was the belt was riding that far forward on the tensioner pulley and was trying to be pulled back into line by the grooved power steering pulley. It was that far out that it has a very high chance of coming off and shredding. It happened to me twice and I actually caught it riding on the outer lip of the power steering pulley once about to come off.
In my case I had to also replace the tensioner pulley arm again as well, as the belt had been riding on the outer edge of this pulley for about 6 months after initially replacing it, before I actually found and had the Harmonic Balancer replaced. So when the Harmonic Balancer was replaced and the belt was riding correctly the tensioner was jumping and rattling badly. You could hear it rattling when inside the car.
Now all is well, belt running correctly in line, tensioner quiet, happy days.
Hopefully this will help someone out as it took me ages to find and fix this problem. Remember that the belt riding forward on the tensioner pulley is the symptom and not the cause. The root cause was the Harmonic Balancer even though the Harmonic Balancer appeared fine.

 

[devilly]

belts are easy to put back on all the ribboned outside on first and then flat side thats how i remember how to do it

well done i know how hard it is to work them out.
but when you replace the drive belt tensioner and its only 6mnths old you wouldn't think the spring inside would let go.<---just happened to me.

easiest and cheapest way to work it out is video record it from top and both side's and then watch the video which you can slow down.

it pick's up stuff the naked eye can't.

 

[vladimir-brazil]

VS V6 Serpentine Belt riding forward on belt tensioner pulley

Hi Guys,
I have recently had problems with my Serpentine Belt riding forward on my Belt Tensioner pulley to such a degree that it was partial off it. The belt had slipped off and disintegrated itself once , so I decided to replace the tensioner itself with a new one. Put it all back together and it was exactly the same.
I have read heaps of items on here about similar situations but never any fixes for it. Well I have fixed the problem and will share what it was and how to check if it is the same problem in your situation.
What fixed the problem was replacing the Harmonic Balancer. This was on a VS V6 with 250,00km but would be the same on most of the V6 Ecotec Engines that followed. If you are experiencing a similar problem, here is what to look for.
Looking down at the idler pulley between the Harmonic Balancer and the Air Conditioner pulley ( bottom & right of the harmonic balancer) you should see the belt is running forward slightly on that pulley. You should see the shiny part slightly exposed where the belt was normally running beforehand and is now moved forward slightly. It could be as little as 1 to 2mm, it was in my case. This amount of movement will show up at the tensioner pulley as being around 6 to 8mm out.
The result was the belt was riding that far forward on the tensioner pulley and was trying to be pulled back into line by the grooved power steering pulley. It was that far out that it has a very high chance of coming off and shredding. It happened to me twice and I actually caught it riding on the outer lip of the power steering pulley once about to come off.
In my case I had to also replace the tensioner pulley arm again as well, as the belt had been riding on the outer edge of this pulley for about 6 months after initially replacing it, before I actually found and had the Harmonic Balancer replaced. So when the Harmonic Balancer was replaced and the belt was riding correctly the tensioner was jumping and rattling badly. You could hear it rattling when inside the car.
Now all is well, belt running correctly in line, tensioner quiet, happy days.
Hopefully this will help someone out as it took me ages to find and fix this problem. Remember that the belt riding forward on the tensioner pulley is the symptom and not the cause. The root cause was the Harmonic Balancer even though the Harmonic Balancer appeared fine.

It appears to me that I have the exact same symptoms that your excellent solution post describes:

"The result was the belt was riding that far forward on the tensioner pulley and was trying to be pulled back into line by the grooved power steering pulley. It was that far out that it has a very high chance of coming off and shredding. It happened to me twice and I actually caught it riding on the outer lip of the power steering pulley once about to come off."

Though, I do not see the cause, at least in the same spot that you found yours, at least looking at the (several) photos I took.

I described all the problem inside a google photos album, in order to help solve my issue and, if solved, permanently help to solve other commodore owners similar issues:

https://goo.gl/uEExqk

The first "photo" is actually a video when I start the car and, instantly, the belt misaligns going to the front part of the tensioner pulley. Same symptons, right?

Any help will be indeed appreciated! Thanks in advance!

 

[rambunctious]

Remove the belt, THEN check all pulley's for alignment using steel rulers, straight edges, or similar, and check them against each other, both horizontal and vertically.
Also while the belt is off, check everything for looseness/play and replace as necessary anything which is loose or wobbly.

 

[vladimir-brazil]

Great!

As you suggested, I'll try methods like these, shown in this site (http://chillerchoong.blogspot.com.br/2010/09/explaining-v-belt-drive-misalignment.html?m=1) to detect every possible misalignment.

I'll post the findings!
Thanks!