cuttingedge
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- Joined
- Jan 9, 2025
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- 31
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2005 GMC Yukon AWD 5.3. Long story short. Oil pressure reads zero at startup but if you stab the throttle comes up to normal. Replaced sending unit same thing. Replaced the pickup tube and o-ring same thing. Manual pressure gauge indicates zero pressure until stabbing the throttle, at which point pressure will hold 40 pounds at hot idle. If I add 2 xtra quarts of oil normal pressure at startup and will maintain 40psi at hot idle. Scan tool verifies the same.
The engine makes no noise whatsoever and runs fantastic. What else could cause this? With 6 quarts (spec'd amount full on dipstick) no pressure at startup. Stab the throttle and it will maintain 40psi at idle and go up to 50 or so when accelerating and maintain over 40psi driving at normal speeds.
My mechanic and I are baffled. If it were bearing or oil pump wear it shouldn't maintain 40lbs at idle for as long as you care to run it.
The truck has 207k miles on it and has had full synthetic oil changed like clockwork for its life.
The engine makes no noise whatsoever and runs fantastic. What else could cause this? With 6 quarts (spec'd amount full on dipstick) no pressure at startup. Stab the throttle and it will maintain 40psi at idle and go up to 50 or so when accelerating and maintain over 40psi driving at normal speeds.
My mechanic and I are baffled. If it were bearing or oil pump wear it shouldn't maintain 40lbs at idle for as long as you care to run it.
The truck has 207k miles on it and has had full synthetic oil changed like clockwork for its life.
