1994 GMC Sierra High Speed Engine Knock

Tiny
NAVY GUY
  • MEMBER
  • 1994 GMC SIERRA
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 130,000 MILES
I recently changed the oil in my truck and then noticed while driving over 60Mph there is a knocking noise. It's not immediate when I go over 60 Mph it's only after I've been driving for about ten minutes. I only use the truck to go to work (15 minutes both ways on the highway). When I pull over to investigate the noise it only last about five minutes and then no noise. When I drive in the city there is no noise it's only at high speed when driving over ten minutes. I did notice when I do her the noise the power doesn't seem to be there if I give it more gas.
Saturday, March 29th, 2014 AT 9:18 AM

2 Replies

Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
The oil may be breaking down or the oil pump ma be getting weak and you could have insufficient oil pressure. I would do a manual oil pressure test and see how much it drops when it gets hot.
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Saturday, March 29th, 2014 AT 10:38 AM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
MAYBE THE OIL DRAIN HOLES IN YOUR HEADS ARE PARTIALLY STOPPED UP?

MORE OIL MAY BE SORTA TRAPPED UP THERE, THAN IS RETURNING BACK TO THE PAN

THE OIL PUMP MIGHT KINDA STARVE HERE AND THERE

WHAT'S HAPPENING WITH THE OIL PRESSURE GAUGE OR OIL PRESSURE LIGHT, WHEN THE ISSUE IS GOING ON?

THE MEDIC
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Saturday, March 29th, 2014 AT 2:46 PM

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