Idler Pulley Failure

[Gelbster]

I have all the press equipment for removing and replacing bearings in the pulley.
A word of caution if you are using a lot of pressure - example a 20T press. Follow the standard Intelligent Machinist best practices otherwise you may crack the pulley. Despite all this I did crack one of mine ! Most mechanics would not have pre-cleaned the pulley carefully enough to notice the crack !
Do not try to just press out the old bearing. Soak it in penetrating fluid for a few days .Work the bearing slightly in/out and re-soak ,repeat. It may take days before the bearing eventually comes out with reasonable force. No beating with a hammer and drift !
Clean the inside of the pulley scrupulously . Freeze the replacement bearing . Warm up the pulley .I used a little 'bearing fit' as a lube when installing the new bearing.
Make sure it is fully seated .Work quickly because of the bearing fit! Make sure the bearing is 'square' in the pulley. Spin the pulley on the new bearing to check for run out. It is easy to distort the pulley if you are clumsy with an overpowering press.
Check that all the pulleys are aligned with a long straightedge. The a/c pulley on mine needed a shim.
But why do all this? Rock Auto has the Pulley for the price of a bearing !NAFYYY
RockAuto Parts Catalog
and

RockAuto Auto Parts

[texomawaves]

Steve, Do you have the torque spec for the tensioner bolt? Thanks, Chris

[CoBeerToad]

Lost mine with no warning. It didn't seize though. It just fell off. Was just pulling off the expressway and heard a load bang behind me. Didn't know what it was until I tried to make the turn onto the road and realized I had no power steering. Then I realized that the belt must have snapped.

After nursing it home, I checked out the belt and it was in one piece and had no mark on it. Took me a few minutes to figure out I was missing the pulley.

Side note: I found every piece of the pulley, but opted to get a new one anyway along with a new belt.

[Pdwight]

for all I have read about these UD pulleys, I will stick with factory

[lucoche]

Hello guys,

i have a 2001 Boxster S with 204 000 km on it, last saturday night i was coming home, and when i took the highway exit i revmatched downshift in 4th gear, then same for 3rd gear, and then my gf and I clearly heard a KLOK KLOK! right in our back.

Having lost the power steering, i initially thought about a flat tire, but quickly stopped to realize that my tires were all fine and smoke was coming out of the engine bay.

I quickly got back in the car, where now i could see the battery light on, so at this moment i figured out that my Main belt snapped for sure.

I replaced this belt myself at 170 000km in 2017 as a preventive maintenance, but i cheaped out the idlers as everything seemed to be fine with them.....WROOONG!

So as soon as I realized that the belt was gone, i was around 2km from my home so i decided to stare at the coolant temp gauge and try to go back home prior to overheat or just run out of battery, which i managed to do.

Today i opened the cover to discover the damage, remove any dust/chunk/strip/wire of what could initially be called a belt. I even passed the vaccuum in every corner that I could reach. The only damage that i could see was that the upper idler was completely destroyed ... here are a few images










Surprisingly, the bearing of this idler was still super smooth and quiet (i verified it prior to unscrew its bolt from the engine).

So, for all you guys who are thinking about just replacing the bearings inside it, think twice. The steel part of the pulley is actually pretty weak for a Porsche part. One one of my above pictures, look inside how corroded it is, my lower roller also shows the same rust flowers in the interior corner.

My conclusion on my issue is the following:
-The idler roller itself started to break due to fatigue and rust, which ejected the strap off and got worse as the strap was probably pulling hard from other elements in rotation...

My solution:
I ordered directly at Porsche Dealer a new belt, new upper and lower idlers, and the roller of the tensioner, for a 577$ CAD tax in. I will be replacing all the parts in 1-2 days, I will keep you guys updates if there is another problem with my car or not.

Sorry for the long story, thanks for reading!

[Homeoboxter]

Originally Posted by lucoche

Hello guys,

i have a 2001 Boxster S with 204 000 km on it, last saturday night i was coming home, and when i took the highway exit i revmatched downshift in 4th gear, then same for 3rd gear, and then my gf and I clearly heard a KLOK KLOK! right in our back.

Having lost the power steering, i initially thought about a flat tire, but quickly stopped to realize that my tires were all fine and smoke was coming out of the engine bay.

I quickly got back in the car, where now i could see the battery light on, so at this moment i figured out that my Main belt snapped for sure.

I replaced this belt myself at 170 000km in 2017 as a preventive maintenance, but i cheaped out the idlers as everything seemed to be fine with them.....WROOONG!

So as soon as I realized that the belt was gone, i was around 2km from my home so i decided to stare at the coolant temp gauge and try to go back home prior to overheat or just run out of battery, which i managed to do.

Today i opened the cover to discover the damage, remove any dust/chunk/strip/wire of what could initially be called a belt. I even passed the vaccuum in every corner that I could reach. The only damage that i could see was that the upper idler was completely destroyed ... here are a few images










Surprisingly, the bearing of this idler was still super smooth and quiet (i verified it prior to unscrew its bolt from the engine).

So, for all you guys who are thinking about just replacing the bearings inside it, think twice. The steel part of the pulley is actually pretty weak for a Porsche part. One one of my above pictures, look inside how corroded it is, my lower roller also shows the same rust flowers in the interior corner.

My conclusion on my issue is the following:
-The idler roller itself started to break due to fatigue and rust, which ejected the strap off and got worse as the strap was probably pulling hard from other elements in rotation...

My solution:
I ordered directly at Porsche Dealer a new belt, new upper and lower idlers, and the roller of the tensioner, for a 577$ CAD tax in. I will be replacing all the parts in 1-2 days, I will keep you guys updates if there is another problem with my car or not.

Sorry for the long story, thanks for reading!

Wow, thanks for sharing that. I rebuilt all my idlers with new bearings, but those were in much better shape, and only 100k in the car. Maybe yours had been rebuilt too somewhere in the past and this one got a little crack due to pressing the new bearing in and just gave it up now. I heated up mines and cooled down the bearings when I installed them to minimize the chance of damaging the pulleys, because they are indeed made of very thin material.

[lucoche]

Originally Posted by Homeoboxter

Wow, thanks for sharing that. I rebuilt all my idlers with new bearings, but those were in much better shape, and only 100k in the car. Maybe yours had been rebuilt too somewhere in the past and this one got a little crack due to pressing the new bearing in and just gave it up now. I heated up mines and cooled down the bearings when I installed them to minimize the chance of damaging the pulleys, because they are indeed made of very thin material.

I think that you are exactly right about the last detail that was missing to my investigation! Alot of people will not seat on the right surface to press the bearing in and/or out. And on the pictures we can clearly see that the breakage would be pretty similar if we would voluntarily seat on the outer ring and apply big force on the bearing insertion’s axis.

I also use the frozen bearing and slightly heated housings (because of aluminum parts) for the wheel bearings jobs to reduce the interference fit and make pressing work a charm! Thanks for your reply! Porsche should have my parts tomorrow!