Tony Ward

Hi everyone, just picked up a 99 Z28 and it has the wonderful drive belt idler pulley chirp. I've been doing a bunch of research on replacing this. My question is simply, will the Gates #38006 idler pulley from Oreilly's work? From my research so far its 50/50. thank you

DaytonaBlues

According to Oriellys, that idler pulley should be a direct fit...sure hope you are sure that the pulley is the problem. But Each pulley is listed as the correct one for the engine idler, not the one for the A/C though

RPM WS6

iTrader: (3)

I'm not sure which part number is which for the aftermarket pullies, but the confusion over fitment has to do with the fact that GM released a revised alternator bracket during March of 2000, so LS1s built before that date used the older style pulley.

Since yours is a '99, it most certainly would have come with the old bracket and thus the older style pulley. However, if someone changed your bracket to the newer style one at some point (GM issued a TSB for this, for people with older models that had belt chirp), then you would need the newer pulley.

Here are some GM part numbers to help you:

Original ('98-early '00) idler pulley: GM #12564401

Revised (late '00-'02) idler pulley: GM #12563326
Revised (late '00-'02) alternator bracket for the newer style pulley: GM #12563327

I know this doesn't help you with the O'reilly/Gates part number, but incase the first one they give you doesn't fit, now you'll understand the reason why different year LS1s use different pullies.