986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post

Steve Tinker · 07-23-2013, 03:02 PM

Essex....
You are correct re disturbing componants - within 2,000 km of me installing a new belt @ 65,000 km, one of the idler pulley bearings started making a rattling noise & a second bearing felt gritty. This my just be a coincidence, but one never knows....
I replaced all three idler pulleys anyway & also installed the underdrive pulley + new shorter belt.

I think that the only downside to the underdrive pulley is (maybe) that the battery charging can be low IF you drive short trips in traffic (low rpm) with the lights / accesories on.
When I installed my new pulley, I checked the voltage of the alternator and the volts were normalised @ 13.5v when the engine revs hit 1,800 rpm, so keeping above 2,000 rpm should be sufficient to charge normally - sometimes difficult in heavy traffic.

07-23-2013, 03:02 PM	#6
Steve Tinker Registered User Join Date: Dec 2008 Location: Queensland, Australia Posts: 1,522	Essex.... You are correct re disturbing componants - within 2,000 km of me installing a new belt @ 65,000 km, one of the idler pulley bearings started making a rattling noise & a second bearing felt gritty. This my just be a coincidence, but one never knows.... I replaced all three idler pulleys anyway & also installed the underdrive pulley + new shorter belt. I think that the only downside to the underdrive pulley is (maybe) that the battery charging can be low IF you drive short trips in traffic (low rpm) with the lights / accesories on. When I installed my new pulley, I checked the voltage of the alternator and the volts were normalised @ 13.5v when the engine revs hit 1,800 rpm, so keeping above 2,000 rpm should be sufficient to charge normally - sometimes difficult in heavy traffic. __________________ 2001 Boxster S (triple black). Sleeping easier with LN Engineering/Flat 6 IMS upgrade, low temp thermostat & underspeed pulley. 2001 MV Agusta F4.