Low Oil Pressure at Idle When Warm

[Austen Leach]

I have a 2004 Tahoe with a 5.3 flex fuel engine and I've started to have low oil pressure issues at idle when hot only. When I start the truck cold the oil pressure is at 40psi and will go higher whenever I touch the accelerator. But as the temperature starts to rise the pressure will slowly bleed off. At 210 degrees the oil pressure is at 20psi and will go up to 40psi at about 1200 rpms. I've already replaced the oil pump pickup tube o-ring thinking that was it and it didn't solve my problems. Anyone have any ideas?

 

[SnowDrifter]

Have you hooked up a mechanical gauge to read oil pressure?

How many miles on engine?

What oil are you using?

Is this a new symptom?

 

[OR VietVet]

First: Welcome to the forum.

Second: Like Chris said, supply more info to help us help you. Plus, any recent work to the engine besides the o-ring replacement? Are there any different/strange engine noises related to this oil pressure drop?

 

[Austen Leach]

I have about 136k on the odometer, I’ve been using Castrol Edge 5w-30 since I bought the truck when it had about 115k on it, it is a new symptom that started here recently, there are no engine noises at all (knock/flatter/taps), and there has been no other engine work done besides a tune up. I don’t have access to an actual oil pressure gauge to verify but I thought that the 5.3s had a real time gauge and if the sensor went out it would either show zero pressure or max?

 

[OR VietVet]

We are all of the opinion that an actual oil pressure gauge should be attached to where the sensor is and get a reading from a known good pressure gauge and because it is a PITA to remove the sensor, replace it when you take the gauge off.

 

[Austen Leach]

Give me a couple days and I’ll report back with an update. Thanks!

 

[OR VietVet]

Great. Make sure you get the pressure at start up when cold, watch as it warms up, pressure at idle when warm and then at 1200-1500 rpm and watch what it is when you throttle it quickly one time. Don't have to hold the accel but just a quick throttle increase. Some here may not agree but I like to do the complete range of cold/hot and idle/rpm differences.

 

[swathdiver]

I have a 2004 Tahoe with a 5.3 flex fuel engine and I've started to have low oil pressure issues at idle when hot only. When I start the truck cold the oil pressure is at 40psi and will go higher whenever I touch the accelerator. But as the temperature starts to rise the pressure will slowly bleed off. At 210 degrees the oil pressure is at 20psi and will go up to 40psi at about 1200 rpms. I've already replaced the oil pump pickup tube o-ring thinking that was it and it didn't solve my problems. Anyone have any ideas?

Austen, what oil filter are you running presently? Do you always use this filter?

 

[Austen Leach]

Austen, what oil filter are you running presently? Do you always use this filter?

I was running a Wix like I had been since I bought the truck when the issues showed up. When I swapped the pickup tube o-ring and changed the oil I replaced it with an AcDelco because I had read that the oil filters could be causing an issue with low oil pressure

 

[swathdiver]

I was running a Wix like I had been since I bought the truck when the issues showed up. When I swapped the pickup tube o-ring and changed the oil I replaced it with an AcDelco because I had read that the oil filters could be causing an issue with low oil pressure

After my engine's oil had 4K+ miles on it, the pressure when hot, stopped at a light in gear, would also drop down to about 20 psi. I was using a Mobil 1 filter and have since switched off to K&N and pressure has returned to normal. I have no experience with WIX and stopped using the ACDelco E-Core filters, change your filter to something else and see, leave the old oil in there save for what you need to top it off.

 

[OR VietVet]

I have used WIX filters before and the NAPA filter is made by WIX. With this 2002 Tahoe of mine I have used AC Delco with no problems. I wonder why some of us have probs with an AC Delco filter and some don't.

 

[Austen Leach]

After my engine's oil had 4K+ miles on it, the pressure when hot, stopped at a light in gear, would also drop down to about 20 psi. I was using a Mobil 1 filter and have since switched off to K&N and pressure has returned to normal. I have no experience with WIX and stopped using the ACDelco E-Core filters, change your filter to something else and see, leave the old oil in there save for what you need to top it off.

Just looked under the truck again and forgot I had actually been running a Wix, then swapped only the filter to a Delco one, then swapped to a Wix XP (which is there "best" version) when I did the o-ring

 

[Austen Leach]

I have used WIX filters before and the NAPA filter is made by WIX. With this 2002 Tahoe of mine I have used AC Delco with no problems. I wonder why some of us have probs with an AC Delco filter and some don't.

I've only been running Wix filters because I had gotten a box of 12 of them for really cheap when I worked at my previous job and they were swapping filters over to another brand

 

[swathdiver]

Just looked under the truck again and forgot I had actually been running a Wix, then swapped only the filter to a Delco one, then swapped to a Wix XP (which is there "best" version) when I did the o-ring

For the process of elimination, I'd still swap out the WIX for something else.

 

[Austen Leach]

For the process of elimination, I'd still swap out the WIX for something else.

Gotcha I'll pick up a filter on my way home and see what happens. I don't like K&N to much so is there any other filters y'all recommend?

 

[SnowDrifter]

I have about 136k on the odometer, I’ve been using Castrol Edge 5w-30 since I bought the truck when it had about 115k on it, it is a new symptom that started here recently, there are no engine noises at all (knock/flatter/taps), and there has been no other engine work done besides a tune up. I don’t have access to an actual oil pressure gauge to verify but I thought that the 5.3s had a real time gauge and if the sensor went out it would either show zero pressure or max?

Started recently after what? Come on man don't make us pull teeth for info.

If you want to withhold stuff, good luck and use Google. If you want us to help you, volunteer information.

 

[Austen Leach]

Started recently after what? Come on man don't make us pull teeth for info.

If you want to withhold stuff, good luck and use Google. If you want us to help you, volunteer information.

It literally just started? I'm not withholding any information? If I had any other info besides I literally was driving and then looked down and watched the gauge drop down I would give it to you.

 

[SnowDrifter]

It literally just started? I'm not withholding any information? If I had any other info besides I literally was driving and then looked down and watched the gauge drop down I would give it to you.

Even that bit is good info

Was pressure good prior to this event? Any changes? Even minor?

 

[Austen Leach]

Even that bit is good info

Was pressure good prior to this event? Any changes? Even minor?

The pressure was good running 40psi and 50-60psi on the accelerator. No weird driving or stopping up to the point where I was sitting and then it decided to bleed off and then has been that way ever since. Every morning I get in it to go to work and it has 40psi and stays pretty close to 40psi until I get closer to 210 degrees on the temperature gauge

 

[OR VietVet]

The pressure was good running 40psi and 50-60psi on the accelerator. No weird driving or stopping up to the point where I was sitting and then it decided to bleed off and then has been that way ever since. Every morning I get in it to go to work and it has 40psi and stays pretty close to 40psi until I get closer to 210 degrees on the temperature gauge

I ran shops for over 30 years and when I talked to a customer I asked a bunch of questions to help narrow down the diagnostic procedure. I told them many times that I wanted exact detailed chronological info for what they were experiencing and for what they may have done to try and correct the problem, if they did anything at all. I said many times as an example; "If you only experience the problem on the second Sunday of the month when turning left over the railroad tracks and it is raining at 2 o'clock in the afternoon, I WANT TO KNOW THAT." That is why we ask so many questions.