LBZ engine noise at idle

[harry320]

I have an LBZ with 11,000 miles that just started making a noise at Idle. This noise of course is hard to describe. The service adviser is calling it a "rhythmatic

[More Power]

Could be EGR or the turbo, but odd sounds are hard to track down. There's a section in the GM service manual that describes how a dealer tech should interpret odd sounds reported by a customer. It's a little humorous, actually.... :)

Try to get the dealer to watch EGR & turbo control signals, as well as injector fuel rates & rail pressures via a Tech II scan tool. He might be able to see a variation in the data that matches the cyclic sounds you're hearing.

Jim

[harry320]

Thanks for reply. After the three days at the dealer they say it is the fan clutch! Seems odd that a truck with 10,000 miles would need a fan clutch, but I guess it can happen. Harry