Novak Conversions Jeep Wrangler TJ radiator

Whistling sound from 4.0

Yes. It almost certainly is. That spacer is also useless. I am not the typical "OEM or it's garbage" guy like many on here. I have a built stroker. That being said, remove it and enjoy your quiet throttle body.
 
I had a whistle couple weeks ago also. I couldn't find any good suggestions but did find throttle body bolts accepted a turn or so, hoping that was it, haven't tested with a long drive yet but short drive had no whistle.
 
Check for vacuum issues too. Could be a split hose, or the rubber elbow going into the intake for the HVAC supply. Mine was whistling, because it had split open.
 
AMS417 said:
Check for vacuum issues too. Could be a split hose, or the rubber elbow going into the intake for the HVAC supply. Mine was whistling, because it had split open.
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Same issue here, years ago. A turn or two of the last bolt closest to the firewall on the exhaust manifold cured my high pitch whistle.
 
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I had the same issue, swore it was a vacuum noise, it was an idler pulley. It nothing in the air / exhaust system looks or feels off, pop off the belt and feel the bearings in the idlers.
 
Novak Conversions Jeep Wrangler TJ radiator
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