Knocking noise at speed.

198,000 MILES • 4.8L • V6 • RWD • AUTOMATIC
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JAMAYWALD
  • MEMBER
  • 2 POSTS
My truck has started making a repetitive knocking noise when travelling at medium to high speeds. The lowest I've noticed it starting up was about 30mph, but once it starts up, it sometimes persists even to lower speed.

It doesn't seem to get worse when cornering or braking, and in fact, braking sometimes causes it to stop temporarily.

I stopped and looked around, checking all four wheel for anything loose or hanging, and couldn't find anything visible, paying special attention to the rear wheels, as it sounds like it's coming from behind me, though it's hard to tell if it's the drivers side, or something closer to the center.

The noise seems to match the pace of the wheel rotation, being more frequent as i go faster, and it stops completely as I slow down, though at what speed it stops varies. It is loud enough that I could easily hear it over the radio and wind noise at highway speeds with the windows up. It is a quite distinct knock or clunk sound, not a whirr or hum or any other more contiguous noise.
Mar 14, 2016 at 12:22 AM
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HMAC300
  • ✓Experienced Mechanic
  • 48,601 POSTS
try driving in a circle doesn't matter see if it amplifies if not try in other direction so if left hand circle would be right hand wheel bearings etc.
Mar 14, 2016 at 12:32 AM
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JAMAYWALD
  • MEMBER
  • 2 POSTS
@HMAC300 turning doesn't seem to have any noticeable effect on the noise, except that usually when I'm turning more sharply, I slow down enough that it stops. I will try to find somewhere I can try to safely drive in a continuous circle at slightly higher speeds, but I may not be able to.
Mar 14, 2016 at 12:53 AM
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HMAC300
  • ✓Experienced Mechanic
  • 48,601 POSTS
from your description sounds like a wheel bearing and doing a circle will make one side spin faster so it may
Mar 14, 2016 at 1:09 AM
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