buffy

Here’s my concern. I have a 1996 Chevrolet Tahoe with 85,000 miles on it. It has had a Whipple supercharger installed from 10,000 miles onward. I have serviced the supercharger consistently throughout its life. Within the last month, I have noticed a change in the noise emitted from the supercharger at speed and moderate load. Before, the sound was an obvious screw meshing sound that cycled from loud to quiet to loud within a period of about two seconds. It has always been a distinctive, cyclic sound that I could hear under a moderate load. At times, it has almost put me to sleep on roadtrips because of it’s white-noise consistency.

Recently, the sounds have become erratic. It happened, all of the sudden. It now sounds like something is loose. Like the tolerances are out of whack. There’s this inconsistent clatter of noise that sounds like the screws are bangin’ around. The sound can only be heard after the engine has warmed up, under moderate load. Like when you’re accelerating from 60mph to 70mph on the freeway. You can rev all day long in park and never hear a thing. It must have a load.

Does this sound familiar? I’ve put about 500 miles on the truck since the problem started. I want to avoid a catastrophic failure if there’s a problem.

After speaking with Steve @ Whipple the other day, he asked me to check for noise by removing the belt and rotating the pulley counterclockwise then clockwise.

Here are my observations: I hear a consistent faint noise as I turn it both counterclockwise and clockwise. I'm not sure what Steve's threshold for 'any' noise equates too; however, this noise sounds like the screws turning inside. I emphasize that it is a very small sound and very smooth and consistent with movement.

Steve stated if I could hear anything, then it was time for a new assembly ($1,300). Who has some insight on my plight?

Yelo

a clatter amost always indicates spark knock or pre-detonation.....I'm betting the Whipple is fine but you've got an ignition or bad-gas problem

buffy

The noise is external to the engine. I'm familiar with the sound of engine knock. This ain't it.