Idler Pulley Failure - 986 Forum - The Community for Porsche Boxster & Cayman Owners

My idler pulley failed today. No squeaking symptoms prior to the failure which has me concerned. Has anyone heard of a pulley failing without any prior noise? It seized hard enough to bend the bolt that held it in place and of course I lost the serpentine belt. Lost power steering, traction control and ABS and the battery light came on. I made it just off the highway before it started over heating (stupid traffic). Should be back on the road Wednesday when the part arrives at the stealership. Anyone have some insight on the failure and if I should be concerned any further than the idler pulley? Let's hold off on talk about the water pump, there's enough information out there on THAT.

I've not heard of a roller siezing before, usually they rattle and move around on their spindle (as mine did). You can bet that the other idle roller and the tensioning roller will be candidates for replacing too if one has already failed. Just be carefull when you torque up the bolts - DONT use the torque specs in Dempsy's 101 Projects for your Boxster book, they are wrong. I know from hard experience .......

My idler pulley whined for 25000 km and gradually got worse. I used a hollow pipe and pressed it against each pulley bolt head until one was obviously the culprit. Then replaced it. Maybe you were just used to the noise??? I wonder what bent the bolt?

I had the AC idler seize on my Toyota without warning, of course the 36" mud tires may have covered up the sound

I forgot where, but there's a site you can order a new bearing for around 5 dollars and have the old ones pressed out and new ones pressed in. I replaced the bearing in both mine for under $20.

I think I would've noticed a whine, this is my second Boxster and this one happens to be quieter. I'm not sure how the bolt bent, I'm thinking it was coming loose and this allowed the pulley to pivot and jam on the belt. I'm glad the bolt wasn't broken clean off! All things considered it's a a relatively cheap fix. I splurged on the OEM dealer part since the turnaround time was relatively quick.

Can anyone tell me what the torque is on the pulley?

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6203-2RS Bearing 17x40x12 Sealed Ball Bearings:17mm

Idler shaft torque values. Upper idler (M10 x 145mm bolt) = 65 Nm (48 ft-lb). Lower idler (M8 x 55mm bolt) = 23 Nm (17 ft-lb).

Quotes source post: 384543

Great link. Thanks! Just one per pulley? Two fixed pulleys and the tensioner?

Yes and yes. When my first idler went, I also tried the replacement bearing rout. Bought good quality SKF deep groove ball bearings and (with difficulty) pressed out the old units and installed the new ones. Looked OK on the bench, but 5,000km later (on the annual service) when I checked my belt and tensioners, one new bearing was very gritty & the other slightly rough - they wouldn't have lasted much longer. I replaced them both with genuine Porsche rollers. So be careful, as you need a good press and be very accurate with your alignment when pressing in the new bearings!

Thanks guys, I appreciate it. Hopefully once I put this new pulley on I don't find any other issues because of the overheating.

Porsche quoted me $103 each for the two deflection rollers and $117 for the tensioner roller. Both of my DRs have slight play in them. May just do that for piece of mind and a new roller surface but new roller bearings for $25 is tempting to try. I pressed my own wheel bearings in. Question. Is there an optimum tensioner position? After UD pulley, I had to experiment with a few belts and one fits great but the tensioner is very close to its fully retracted position. Also, belt brand? I'm finding with my WP swapped that some start up noise is just belt squawk like a scrunch sound for a minute until it warms up. A shot of WD makes it quiet for a few days then it's back.

When I installed my underdrive pulley (bought from Flat6), it came with Gates belt Micro-V AT #K060806. A bit of a tight fit if I remember correctly, but runs OK. By the way, WD40 is not good for a belt - better to use a proper belt dressing lubricant which lasts much longer.

I never use belt dressing, in my experience it just collects dirt, and makes the belt run loud.

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That's why I was thinking new belt or different brand. Napa is close to my shop and had the black belt dressing but it's like tar and sticky and actually made the belt more audible.

Price on new pulleys is about $70 each for oem supplier from Pelican. And AutoZone has these at 45 each. Has anybody use the Duralast from autozone before? Also the parts at autozone are the same part for upper and lower pulley, but I know they're separate part numbers at Porsche. I wonder about this.

WD40 is not good for anything....seen lots of fine antique firearms ruined because WD40 (Water Displacing) removed all the petroleum in the steel and they were stored in that consition....use a specific product like was recommended

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

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