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Steve Tinker · 11-18-2013, 02:20 PM

Shehadehd....
I can't help you with the CEL, but after fitting your new underdrive pulley, I imagine you fitted a new belt too. Its a fair bet that one of the idler roller / tensioner roller bearings or alternator free wheel pulley has given up with the extra tension of the new belt. Or the new underdrive pulley is loose.
Try running the engine with the rear engine cover removed to get a good idea of the noiseclose up and then run the engine without the accessory belt fitted and see if the noise disappears.
Don't run without the belt connected for more than a minute or two as the coolant pump won't be operational.
I had to replace all my roller bearings plus the alternator free wheel within about 1000km after fitting my UDP, so I know the feeling....

11-18-2013, 02:20 PM	#10
Steve Tinker Registered User Join Date: Dec 2008 Location: Queensland, Australia Posts: 1,522	Shehadehd.... I can't help you with the CEL, but after fitting your new underdrive pulley, I imagine you fitted a new belt too. Its a fair bet that one of the idler roller / tensioner roller bearings or alternator free wheel pulley has given up with the extra tension of the new belt. Or the new underdrive pulley is loose. Try running the engine with the rear engine cover removed to get a good idea of the noiseclose up and then run the engine without the accessory belt fitted and see if the noise disappears. Don't run without the belt connected for more than a minute or two as the coolant pump won't be operational. I had to replace all my roller bearings plus the alternator free wheel within about 1000km after fitting my UDP, so I know the feeling.... __________________ 2001 Boxster S (triple black). Sleeping easier with LN Engineering/Flat 6 IMS upgrade, low temp thermostat & underspeed pulley. 2001 MV Agusta F4. Last edited by Steve Tinker; 11-18-2013 at 02:24 PM.