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Loss of oil pressure

BonesDMC

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BonesDMC Enthusiast

BonesDMC

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I have a 2004 Tahoe with a 5.3 flex engine. I have been having issues with the oil pressure for the past 2 years. I can drive for 3 months with no issue and then it starts acting up by loosing pressure and sending the system into alarm. I took it to the dealer and they said it had good pressure. I replaced the oil sending unit and thought everything was fine. I had it out and pulled into traffic, pulling about 5500 rpm's and shortly after that, the pressure dropped and system went into alarm. Checked oil and it was only one hole down on stick. Figured it was just the screen or switch or cluster, went to go home when the engine started knocking, bad. Turned it off and tried to limp it home. After 5 min stopped, the oil pressure returned and everything looked good. Went about 10 miles and everything was good when it dropped again. Then it returned again. Got it home and oil on stick was only one hole down on stick. Does anyone have advise? The engine only has 130000 on it. I do loose about 1 qt of oil every 500 miles. and loose about 1 gal of coolant every 10000 miles. Never see any smoke or leaks. I am thinking I need an engine overhaul, but only 130000 mile out of an engine. Seems that I should have got more. I have owned the truck since new and changed oil every time the oil sensing system got to 10 percent.

BonesDMC Enthusiast

BonesDMC

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Couple of things to add, it should read I am loosing 1 qt of oil every 5000 miles. When I took the truck to the dealer, it was in alarm and the engine was knocking, slightly, when the pressure was low. The dealer said the pressure was ok and the gauge on the cluster was bad. Dealer said the knocking was from the cam. Do not know how they determined that, but knock went away when pressure returned. I have gone all summer without an issue. It seems that I get these issues when I rev the engine over the 5000 mark. After a while everything returns to normal. This time the knock was bad, and almost cut off. I know, just do not rev the engine..... but I like too.

2018GMC Senior Enthusiast

2018GMC

Posted
Posted

Missing coolant could be a few things. Intake manifold gasket leaking, or more commonly water pump going bad which will slowly weep coolant which is hard to detect until the leak gets worse. Maybe take it to another mechanic for a second opinion?

BonesDMC Enthusiast

BonesDMC

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Replaced the water pump 18 months ago. Slowed the leak down. I believe I burn water when I start up but stops when engine gets warm. I saw this was a common problem with the head gasket. My biggest concern is the oil pressure with the knock.

WilliamBos Senior Enthusiast

WilliamBos

Posted
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Another problem they have is the o-ring on the oil pick up tube. When the engine is running that part of the tube is NOT submerged in oil, if the o-ring is shot, it will suck air and cause this issue too.

BonesDMC Enthusiast

BonesDMC

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I looked at the screen, but that would only explain the loss of oil pressure, I have noise when the pressure gauge goes down, this would tell me that I am losing pressure to the engine, or part of it. Did not know about the o ring. Might explain symptoms, this only really happens after I Rev the engine high. Symptoms of losing pressure and it coming back and various back and forths.

muddkatt Senior Enthusiast

muddkatt

Posted
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Your AFM lifters are probably crapped out.....

 

04's don't have AFM lifters.

WigglesTheHoly Enthusiast

WigglesTheHoly

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From my personal experience with oil pressure issues, I replaced the oil pump, and the pickup tube. The knock, which almost sounds like a diesel, was the lack of pressure causing some lifter knock. Just my experience may not be your issue. Mine was on an 05.

WilliamBos Senior Enthusiast

WilliamBos

Posted
Posted

I looked at the screen, but that would only explain the loss of oil pressure, I have noise when the pressure gauge goes down, this would tell me that I am losing pressure to the engine, or part of it. Did not know about the o ring. Might explain symptoms, this only really happens after I Rev the engine high. Symptoms of losing pressure and it coming back and various back and forths.

http://www.gm-trucks.com/forums/topic/151001-2005-gmc-sierra-1500-4x4-53-oil-pickup-tube-o-ring-replacement/

BonesDMC Enthusiast

BonesDMC

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From my personal experience with oil pressure issues, I replaced the oil pump, and the pickup tube. The knock, which almost sounds like a diesel, was the lack of pressure causing some lifter knock. Just my experience may not be your issue. Mine was on an 05.

This is what I was thinking. Did sound like a diesel

BonesDMC Enthusiast

BonesDMC

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Looked at this post. Says only 7 hours to remove front diff and drop oil pan to replace oil pump. Very doable. With the head gasket issue I think I have (losing water and oil over time), I think I might just rebuild the whole engine. I love the truck and body/undercarriage looks good. Wife hates the newer designs, wants to keep truck as well. I will look into both fixes and update on which way I go.

WigglesTheHoly Enthusiast

WigglesTheHoly

Posted
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Looked at this post. Says only 7 hours to remove front diff and drop oil pan to replace oil pump. Very doable. With the head gasket issue I think I have (losing water and oil over time), I think I might just rebuild the whole engine. I love the truck and body/undercarriage looks good. Wife hates the newer designs, wants to keep truck as well. I will look into both fixes and update on which way I go.

 

I replaced mine without dropping the front end. It's actually pretty simple and saves a BUNCH of time. Make sure you have a flexible magnet and some fishing string ready. So when GM put the oil pumps on our trucks they added a flange on and all you need to do is remove the keyed piece stopping the flange from spinning around because right there where it would be easily accessible if you turn the flange 180 degrees is another bolt hole for the pickup tube.

 

Not my video, but he did what I did.

did that almost 40k miles ago.
BonesDMC Enthusiast

BonesDMC

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I replaced mine without dropping the front end. It's actually pretty simple and saves a BUNCH of time. Make sure you have a flexible magnet and some fishing string ready. So when GM put the oil pumps on our trucks they added a flange on and all you need to do is remove the keyed piece stopping the flange from spinning around because right there where it would be easily accessible if you turn the flange 180 degrees is another bolt hole for the pickup tube.

 

Not my video, but he did what I did.

did that almost 40k miles ago.

Great advise, thanks

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