Another oil pressure saga!

[JKaechler]

On my 2011 Tahoe with roughly 200k on it, I have the classic symptom of low oil pressure after it warms up. I will be swapping the sensor and deleting the little screen this weekend, but i dont hold out much hope that will resolve it.

So, assuming i am moving onto the o-ring on the pickup tube: Do I need to plan to replace the oil pump while i have the pan off? Its a 4x4, so pan removal looks like it will be a pain, but not the end of the world.

if so, high volume pump? or standard pump? I dont race or anything, i bet the engine will hardly ever see more than 3500rpm.

 

[Dustin Jackson]

@JKaechler For the O-ring you just need to drop the steering rack, front diff, and oil pan. The oil pump shouldn't need to be replaced and would involve removing the front of the engine.

You should be able to drop the front diff only slightly to make enough room for the oil pan to slide out

 

[B-train]

I'd do the pickup tube and all the oil o-rings under the plenum on top. I wouldn't worry about the pump. My guess is it's justeakafe due to age and compression of materials

 

[B-train]

Geez....sorry about these darn fat fingers. Should read:

My guess is it's just leakage due to age and compression of materials

 

[JKaechler]

I'd do the pickup tube and all the oil o-rings under the plenum on top. I wouldn't worry about the pump. My guess is it's justeakafe due to age and compression of materials

o-rings under the plenum?

 

[B-train]

I believe they are called the VLOM. Others can correct me if I'm wrong. There are oil passages under the top engine engine cover below the plenum that activate the AFM. On non-AFM motors, there's just block off o-rings and a plate. I've done a few sets due to them weeping internally back into the valley causing lower oil pressure when hot.

 

[TollKeeper]

I am wondering the same as @B-train , wondering if its not just a failing VLOM actuator.

 

[JKaechler]

we are talking about this part?

https://www.amazon.com/Fel-Pro-MS-96871-Intake-Manifold/dp/B0033DNA5S/ref=sr_1_2?crid=1AGIC5066KXSB&keywords=MS96871&qid=1681420271&s=automotive&sprefix=ms96871%2Cautomotive%2C200&sr=1-2&ufe=app_do%3Aamzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840

to get to that, you take out the intake manifold and the valley cover below it?

 

[TollKeeper]

Kinda.... Below the oil pressure sensor is a port that provides oil to that VLOM setup..

When one of those actuators fail on the VLOM, oil bypasses it, potentially causing issues with the AFM/DOD.

On my 5.3 AFM/DOD, I plugged off that port to the VLOM (link below of what I used), and it completely corrected my Oil PSI issue, and I dont have to worry about the AFM/DOD as a plus.

Product Page | Crazed Performance R

www.crazedperformancerepair.com

Just had to get a tune to remove the AFM/DOD, and modified the VLOM, as instructed by crazed performance, to make sure it would not bother me again, hopefully!

 

[swathdiver]

On my 2011 Tahoe with roughly 200k on it, I have the classic symptom of low oil pressure after it warms up. I will be swapping the sensor and deleting the little screen this weekend, but i dont hold out much hope that will resolve it.

So, assuming i am moving onto the o-ring on the pickup tube: Do I need to plan to replace the oil pump while i have the pan off? Its a 4x4, so pan removal looks like it will be a pain, but not the end of the world.

if so, high volume pump? or standard pump? I dont race or anything, i bet the engine will hardly ever see more than 3500rpm.

Put two more quarts into the motor and then check the pressure idling or driving around. If the pressure stays up, it's the o-ring. If it does not, the problem is elsewhere.

 

[JKaechler]

Put two more quarts into the motor and then check the pressure idling or driving around. If the pressure stays up, it's the o-ring. If it does not, the problem is elsewhere.

i read somewhere that this test needs to be done on a slope? and its bad to leave the over capacity in there for a long time?

 

[swathdiver]

i read somewhere that this test needs to be done on a slope? and its bad to leave the over capacity in there for a long time?

1 quart with a sloped drive. Some guys say to add 2 quarts and use a sloped drive to check it. I learned on these forums that 2 quarts and a flat driveway is good enough.

You can drive around with it, a guy on here who was down on his luck drove his truck like that for two years until he could make the repair.

 

[JKaechler]

1 quart with a sloped drive. Some guys say to add 2 quarts and use a sloped drive to check it. I learned on these forums that 2 quarts and a flat driveway is good enough.

You can drive around with it, a guy on here who was down on his luck drove his truck like that for two years until he could make the repair.

that is excellent information! I will conduct that test in the next few days. many thanks!

 

[Tom-M]

On my 2011 Tahoe with roughly 200k on it, I have the classic symptom of low oil pressure after it warms up. I will be swapping the sensor and deleting the little screen this weekend, but i dont hold out much hope that will resolve it.

So, assuming i am moving onto the o-ring on the pickup tube: Do I need to plan to replace the oil pump while i have the pan off? Its a 4x4, so pan removal looks like it will be a pain, but not the end of the world.

if so, high volume pump? or standard pump? I dont race or anything, i bet the engine will hardly ever see more than 3500rpm.

I had a 2008 Trail Blazer with the 5.3L in it. When it got warm, the oil pressure would drop to zero and a warning would come up on the DIC. I changed the sending unit and it still did it. When I took the new unit back out a second time, I dropped the screen and it was never to be seen again. I put the old sending unit back in and the oil pressure read correctly from that point on until I sold the vehicle.

 

[Geotrash]

I had a 2008 Trail Blazer with the 5.3L in it. When it got warm, the oil pressure would drop to zero and a warning would come up on the DIC. I changed the sending unit and it still did it. When I took the new unit back out a second time, I dropped the screen and it was never to be seen again. I put the old sending unit back in and the oil pressure read correctly from that point on until I sold the vehicle.

Correct. It's not usually the sender itself that's the culprit for low oil pressure readings - it's the screen.

 

[j91z28d1]

but if you have the afm running, I wouldn't leave it out. replace or clean.

all that stuff that clogged your screen would be pumped thru the inside of your lifters, which have very tight tolerances. once a lifter sticks you're pulling a head at best.

if that's clogged it probably means you have sludge in your engine. mine was clean at 135k when the sensor when out(failed maxed out), but the inside of the engine is spotless. I'd love to know what the previous owner did for maintenance. what I saw on car fax was nothing special.

 

[Geotrash]

but if you have the afm running, I wouldn't leave it out. replace or clean.

all that stuff that clogged your screen would be pumped thru the inside of your lifters, which have very tight tolerances. once a lifter sticks you're pulling a head at best.

if that's clogged it probably means you have sludge in your engine. mine was clean at 135k when the sensor when out(failed maxed out), but the inside of the engine is spotless. I'd love to know what the previous owner did for maintenance. what I saw on car fax was nothing special.

Good clarification. I didn’t mean to suggest leaving it out - only that the screen itself is usually the source of the problem and needs to be either thoroughly cleaned or replaced.

 

[j91z28d1]

Good clarification. I didn’t mean to suggest leaving it out - only that the screen itself is usually the source of the problem and needs to be either thoroughly cleaned or replaced.

yeah, I only said that because the post above said he left it out till it was sold. I don't know if a tb has afm? I guess it would since it had the screen.

 

[JKaechler]

An update on this saga, and some background.

I bought this Tahoe 6 weeks ago, and its two issues were the low oil pressure and the tranny was nearly toast. straight to a full trans rebuilt it went. (it was in the budget from the beginning)

This week i got it back from the tranny shop, and immediately changed the oil. on the way home it read about 25PSI when driving around 1500 rpm.
after the oil change it reads about 35psi at idle, and hovers right at 40psi when driving. that is true when cold and also when hot.

I put in 1qt of Lucas oil stabilizer, and the rest is normal quaker state high mileage. I did not overfill as was suggested earlier. I wanted to try it out with a normal amount.

the oil that came out did not seem to be anything horrible. maybe a bit old but fairly normal.

 

[Dustin Jackson]

Your oil pressure levels after the oil change are good, no need for additives or stabilizers in the oil.

I just changed my oil and with this oil + filter combination my oil pressure falls below the 20 mark at hot idle but nothing to sweat about, motor still sounds smooth. Cheap walmart brand dexos oil...