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Spent a whole day chasing a phantom knock in a 6.7 Powerstroke

It was a 2015 F-250 from a farm in Boise, had this weird knock at idle that would vanish under load. I checked the usual suspects, injectors, lifters, even pulled the oil pan to look at the rods. Turns out it was just the freaking AC compressor clutch bearing, making a noise that traveled through the whole block. Took me from 7 AM to almost 6 PM to figure it out. Anyone else had a simple part mimic a major engine problem like that?
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3 Comments
leo_black76
Spent three hours once convinced my Civic had thrown a rod over a loose heat shield rattling.
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morgan_king36
Honestly that heat shield rattle on Civics is a classic. I had the same panic with my old one. Tbh the best fix is to get under there and just rip the dang thing off if the bolts are rusted. It doesn't actually hurt anything to remove it. Saved myself so much stress just doing that instead of trying to re-bolt it.
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shane_park92
My 2006 Civic had that same rattle for a year before I figured it out, @leo_black76. I was sure the engine was about to explode every time I hit a bump. Finally just cut the shield off with tin snips and never heard it again.
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