Oil Pressure

[Wolfbraid]

I read the sticky post above, just putting this for visibility... and input:

Welcome to the club.. ME.... not sure if it was related, but today after a pretty hard acceleration(harder than normal, not 100% throttle) I found myself
with 0 pressure reading, and a "low oil pressure stop engine" DIC message. Engine ran quiet, I pulled over and listened, had my boys with me so I drove home 2 miles to get another vehicle.
No signs of oil loss, levels good, oil looks good and clean. changed the oil about 2000 miles ago with Mobil 1 and I think a K&N filter.

Parked now at home Oil gauge will move slightly if revved up.. engine sounds normal.
I'm aiming at oil pressure switch and the little filter with it as first line.
Although I may change oil/filter first to see if that has effect.

Would love to hear feedback, hope it's not the o-ring because that will have to be a shop job for me, don't have the time or tools for that one.

 

[jcb2]

I feel your pain! I had the same problem with my ‘07 Yukon XL. I stopped the engine and had AAA tow it to a local garage for repair. I was working and couldn’t take the time to check it myself. They said it was just the switch/sensor and replaced it. A year later the same thing happened but this time I let it run to listen and watch the temperature gauge. It didn’t move and the sound was fine. I was convinced that it was another oil sensor gone bad.

I replaced that and I can tell you it’s a PIA to access. There are several on-line posts and videos about this but if you’re handy with tools, you can do it.
It worked fine for a day then the same warnings popped up. It was then that I found out about the little screen that sits under the sensor. So I took the sensor out and replaced the screen. It’s cheap and I don’t understand why the don’t just include it in the box with the sensor. The least the parts guy should do is ask you if you want the screen to go with it. The old screen was really clogged up so I’m sure that was the cause of the trouble. I change the oil regularly but I have no idea if the previous owner was as diligent.

Because I read so much about possible causes of low oil readings,I decided to go further and flush the system and replace the oil suction O-ring. To access that, there’s a lot of work to drop the pan first. I’m very glad that I went the extra mile to do this because I discovered how gunked up my pan was. So I thoroughly cleaned the pan and internal parts and replaced the oil level sensor since it was cheap and might be tough to access later. I reassembled everything with new oil and filter. My oil pressure is now 50-60 and the engine runs so smoothly one can’t even hear it with the hood closed.

The biggest problems I had were snapping off two of the stabilizer bushing bolts and the coil post on the starter. So I replaced the starter too.Nothing I tried (WD40, PB Blater, small pipe wrench, vice grips) could loosen the bolts. I had to drill and tap the bushing bolt holes then install new bolts.

It was a lot of work but a really clean oil system has made a big difference!

 

[Wolfbraid]

Well.... Its back...ding ding ding low oil pressure, very humid and cold today(ICE STORM) Oil level seems ok, I added a qt.

We'll see what tomorrow brings, I guess I'll pull the sensor again and check the filter, if its gunked up, I'll replace it or clean it and try another flush. I hate this one.. wife wants to get rid of this one and get another... hah..

 

[donjetman]

Would love to hear feedback, hope it's not the o-ring because that will have to be a shop job for me, don't have the time or tools for that one.

To determine if low oil pressure is being caused by a bad o-ring between the block and the oil pump pickup tube, overfill the crankcase by 2 qts of oil, start it up, and if the pressure is OK you know where the problem is.

 

[yukonlou]

I was thinking about the oil pressure sender and its filter... Does anyone if the filter servers any additional purpose than to filter oil reaching the sender? I was curious as to how it functions... I am assuming it is fed from a main oil gallery, does if filter oil reaching the lifters via a T connection? More specifically, is it there to protect lifters in engines that shut down some of the cylinders? I don't think they would be filtering any oil going to the sender as the sender opening is pretty large in relation to any particles that might be floating in the oil after being filtered by the oil filter... Never seen any other manufacturer use a pre-filter in their oil pressure sensors...

Comments?

Thanks!

 

[kbuskill]

I was thinking about the oil pressure sender and its filter... Does anyone if the filter servers any additional purpose than to filter oil reaching the sender? I was curious as to how it functions... I am assuming it is fed from a main oil gallery, does if filter oil reaching the lifters via a T connection? More specifically, is it there to protect lifters in engines that shut down some of the cylinders? I don't think they would be filtering any oil going to the sender as the sender opening is pretty large in relation to any particles that might be floating in the oil after being filtered by the oil filter... Never seen any other manufacturer use a pre-filter in their oil pressure sensors...

Comments?

Thanks!

It filters the oil before it goes to the sending unit and the VLOM which has the solenoids that control the AFM lifters.... if I'm not mistaken.

It is there to protect the solenoids more than the pressure sending unit.

 

[yukonlou]

Thanks for your response. So, I guess it makes sense to replace it as preventive maintenance. It is on my list of things to do when I hit 100K.

 

[BADDGMC]

Well.... Its back...ding ding ding low oil pressure, very humid and cold today(ICE STORM) Oil level seems ok, I added a qt.

We'll see what tomorrow brings, I guess I'll pull the sensor again and check the filter, if its gunked up, I'll replace it or clean it and try another flush. I hate this one.. wife wants to get rid of this one and get another... hah..

Did you replace the O-Ring after the 1st time you got the low oil pressure warning?

 

[swathdiver]

Eric, did you change the oil filter yet?

 

[Wolfbraid]

Sorry for the lack of reply, had household issues couldn't get online.
On the 14th the pressure dropped to zero.
So on the 15th/16th it came back
and today its off again.
I flushed and changed the oil, didn't get it on the highway for a test drive, if it persists I'll pull the sensor and check the filter screen again.
Damn that sensor hope I don't drop it like the first one.

I'd rather do my front hub assemblies than the sensor, such a PITA

Anyway last time all I did was the pressure sensor and filter, and it oil pressure was perfect, and back up.
I don't think this is a case of the oil pickup tube, I said F-it and drove it with the dinger(any trick temp or permanent to disable?)

Mechanic at work said if I really had Zero pressure(we have a fleet of Savana's), the engine would be dead already with the driving I've done.

 

[swathdiver]

Eric, did you change the oil filter yet?

??? ^^^^

 

[Wolfbraid]

??? ^^^^

see last post
I changed the oil(which includes a new filter, don't think I've ever considered changing the oil without also changing filter)

If it keeps up tomorrow, i'll pull the sensor and sensor filter tomorrow and see what it looks like...

 

[BG1988]

have you guys ever considered a wire issue? the wires could be shorting out 0 Ω (or OL)= shorted to ground which will give you a reading of 0PSI on the cluster

Honestly it sounds like the wire is shorting out which why it works for a day(as the wires have been moved/adjusted.) then goes back to the issue..


A. the wire(s) has a short to ground =0Ω resistance
B. The wire has an internal break in it (OL= 0Ω resistance, aka no reading)
C. loose connection. at the terminal(s)


if you can read the Ω while it has an issue.. it can rule out an issue with the cluster it self..
vibration is an issues as well I remember with my gm car the oil pressure sensor would read 0psi when going over a very specific speed bump.. only this one speed bump would do this ..

crazy huh?

reproduce able to the very specific speed bump.. other wise i could not get it to happen any other time..

 

[swathdiver]

see last post
I changed the oil(which includes a new filter, don't think I've ever considered changing the oil without also changing filter)

If it keeps up tomorrow, i'll pull the sensor and sensor filter tomorrow and see what it looks like...

I saw it, just wanted to make sure!

have you guys ever considered a wire issue? the wires could be shorting out 0 Ω (or OL)= shorted to ground which will give you a reading of 0PSI on the cluster

How'd you do that ohms thing? My Montana is acting up like this. The engine is running fine but it threw a check engine light last night. Tech-2 could not communicate with it at all. Previously, it could talk to the engine but not the body. Now nothing. Gotta be a ground or broken wire problem.

 

[Wolfbraid]

Another Update... All is well, during my commute, my pressure is reading again...

 

[swathdiver]

Another Update... All is well, during my commute, my pressure is reading again...

So was the culprit the oil filter? If so, anything untoward about it?

 

[Wolfbraid]

So was the culprit the oil filter? If so, anything untoward about it?

The oil filter was a fram XG I think, I didn't cut it apart. This time i just used an ACDelco filter.

My theory:
1. I imagine that the prior owner possibly used only conventional oil, and at my first oil change I switched to Mobil 1 full synth.
The first time this happened, it happened right after I got on the gas HARD... I'm guessing that some gunk or build up broke free and blocked the
Oil Pressure Filter/screen thing.(I know it was blocked because I took it out and replaced it)

Second time it happened again (I think after I got on it hard.) Did an Oil change with Engine Flush... seemed to do the trick.


Another theory, the first owner grandps'd the truck, making built up possible.

Who knows, probably just junk floating around.

 

[swathdiver]

The oil filter was a fram XG I think, I didn't cut it apart. This time i just used an ACDelco filter.

My theory:
1. I imagine that the prior owner possibly used only conventional oil, and at my first oil change I switched to Mobil 1 full synth.
The first time this happened, it happened right after I got on the gas HARD... I'm guessing that some gunk or build up broke free and blocked the
Oil Pressure Filter/screen thing.(I know it was blocked because I took it out and replaced it)

Second time it happened again (I think after I got on it hard.) Did an Oil change with Engine Flush... seemed to do the trick.


Another theory, the first owner grandps'd the truck, making built up possible.

Who knows, probably just junk floating around.

We see and experience this all the time when switching over to synthetic from regular oil. It sometimes does more harm than good and unfortunately, there's no way to know what will happen. I mistakenly put my wife's old Montana onto synthetic last time and now it's got oil problems too as does my driveway! Dumb!

 

[Wolfbraid]

We see and experience this all the time when switching over to synthetic from regular oil. It sometimes does more harm than good and unfortunately, there's no way to know what will happen. I mistakenly put my wife's old Montana onto synthetic last time and now it's got oil problems too as does my driveway! Dumb!

Yes, the only downfall of buying used, with a relatively unknown service history.
I wonder if switching to a blend or back to conventional is a better option.
Also wonder if a aftermarket solution to the oil pressure switch is a good option?

I don't worry about it too much, although I wish you could disable to warning buzzer, its integrated into the stereo.
I imagine I could put a resistor in the plug to fool the ecm and then run an aftermarket gauge...

 

[kbuskill]

Yes, the only downfall of buying used, with a relatively unknown service history.
I wonder if switching to a blend or back to conventional is a better option.
Also wonder if a aftermarket solution to the oil pressure switch is a good option?

I don't worry about it too much, although I wish you could disable to warning buzzer, its integrated into the stereo.
I imagine I could put a resistor in the plug to fool the ecm and then run an aftermarket gauge...

You could run a resistor IN PLACE OF the sensor to trick the ECM and gauge but it's not the best idea. There is a chance you might not be paying attention if/when the oil pressure really does drop to zero and you could do damage before realizing it.

Just keep in mind that the INPUT for the sensor is only 5V so don't just hook 12V up to a resistor and hook it into the OUTPUT wire of the sensor.