Intermittant loss of oil pressure on 5.7

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Nov 8, 2011 | 02:43 PM
  #1  
New to the forum... first post and hope I can get some help...

Last December I made a aggressive pass on the freeway with my 06 QC 4X4 with about 92k miles and then settled back into cruise mode and the check gauges light came on and I looked and had no oil pressure. Slowed down to about 50 mph and opened the window and could hear the motor ticking. We were in the middle of nowhere so I decided to watch the temp gauge and drove for about 10 miles with the motor never getting hot and got to a off ramp & pulled into a gas station with the truck sounding like a diesel. I shut it off and checked the oil and it was full. Totally bummed out I let the truck sit for about 5 minutes and decided to try to start it up and had oil pressure, although low and still clattering. The motor was a little quieter so I decided to take it back on the freeway. It ticked for about another 15 miles and pulled off again and shut it off. Started it back up and had more oil pressure and the ticking was quieter. Drove for another 20 miles and the oil pressure was back to normal and popped the hood and it sounded perfectly normal. Didn't happen again untill I was plowing a couple of weeks later and after about 15 minutes of plowing... every time, the check gauges light would come on and now all I have to do is shut it off for 10 seconds... start it back off and wala - I have oil pressure. It happened about 50 times last winter, almost always while plowing.


Put about 17K miles on the truck since it first happened and it has gone about 4 months... running perfectly but... twice last Sunday while pulling a trailer after trying to pass someone... It did it again... Now I just shut the truck off while going down the freeway @ 65 and coast for 5 seconds, start it back up and I'm good to go!

Nobody has had a answer and the local dealer thinks I'm nuts...

Help!
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Nov 8, 2011 | 08:25 PM
  #2  
Sounds like your pump pick-up is partially clogged and as oil drains back, it pushes some of the crud back out of the way.
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Nov 8, 2011 | 10:40 PM
  #3  
Quote: Sounds like your pump pick-up is partially clogged and as oil drains back, it pushes some of the crud back out of the way.

Where would the "crud" come from?
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Nov 8, 2011 | 11:13 PM
  #4  
I would start by replacing the oil pressure sending unit. My '03 5.7 would do the same thing, but when i first started it up in the morning. It would tell me to check gauges and oil pressure would read zero. I would shut it off and re-start it and it was back to normal. After i replaced the sending unit I haven't had a problem since. It is located right above the oil filter on my '03 and easy to replace...cheap too.
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Nov 9, 2011 | 01:13 AM
  #5  
Quote: I would start by replacing the oil pressure sending unit. My '03 5.7 would do the same thing, but when i first started it up in the morning. It would tell me to check gauges and oil pressure would read zero. I would shut it off and re-start it and it was back to normal. After i replaced the sending unit I haven't had a problem since. It is located right above the oil filter on my '03 and easy to replace...cheap too.
Would you have a real loss of oil pressure with lifter noise?
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Nov 9, 2011 | 03:59 AM
  #6  
I believe that our truck gauges show either just over half way or zero. No inbetween.
A mechanical gauge is the way to go for this one. Monitor this when the problem happens. Theyre cheap and easy enough to install.
Fit one of these to see if your really getting low oil/no oil pressure.
I have read that these senders do go bad on our trucks and a replacement does solve the problem.
However I am concerned, that you said it sounded "like a diesel". That does sound like a problem.
Al.
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Nov 9, 2011 | 09:21 AM
  #7  
I have a 07 5.7L and mine recently did the same thing you are talking about and had to replace oil pump.. The tube was full of gunk(sludge from time) and I had 140k btw
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Nov 9, 2011 | 09:44 AM
  #8  
Quote: I have a 07 5.7L and mine recently did the same thing you are talking about and had to replace oil pump.. The tube was full of gunk(sludge from time) and I had 140k btw
Off topic but..... Was it serviced regularly and was it using synth oil?
Al.
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Nov 9, 2011 | 10:32 AM
  #9  
Yes and Yes........... They said that it just happens.... IDK
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Nov 9, 2011 | 12:05 PM
  #10  
Quote: I have a 07 5.7L and mine recently did the same thing you are talking about and had to replace oil pump.. The tube was full of gunk(sludge from time) and I had 140k btw
Well my oil pan is rusting pretty good so I think this is probably the route I need to go and just replace both... Then I can fix the blend doors, ball joints, collapsed seat, headlight relay, broken exhaust manifold stud Ect....
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