Delco PF48E low oil pressure

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Originally Posted By: WellOiled
I found this thread which covers many possibilities.
GM 5.3L low oil pressure issues.
I’m not sure what the rankings should be.


That's a long thread. Looks like I should use the larger filter and change when the pressure goes down. I have never heard ticking in the lifters so I am pretty sure I don't have a pickup or oil pump problem.

I had changed at 30% which was between 5k-7k with cenex semi syn 5w30 for the first 80K. Then we switched to Cenex Maxtron Dexos 5w30 and changed at 0% which was 7-10k. The last three changes have been with Pronto syn 5w30 Dexos. The oil pressure has always got lower at the end of oil interval; I figured it was due to shearing and lower viscosity, but maybe there is some sludge building up in there??
 
The thread I pointed you to illuded to several fixes to the same reported problem.

1. The highest reported fix was the small filter under the oil pressure sending unit is plugged. This would suggest low reporting of the oil pressure.

2. Without counting the next fix was use a less restrictive filter (more capacity).

3. Next was the O-ring on the oil pump pickup tube not sealing properly.

4. Next would be either a weak oil pump or oil pump pressure regulator is sticking open.

5. Next was an O-ring on a cover on the end of a camshaft.

If this were my truck, I would likely try the larger, less restrictive filter and do some short oil and filter changes to address the cleanliness issue. If this does not resolve the issue, then start down the list of solutions until you meet success or your repair budget.
 
GM has some wacky rationale for downsizing the filter for the LS engine that they really patted themselves on the back for.

This was mysterious to me, because GM traditionally used the largest filter possible for the application without scraping the ground in the previous generation.

Cars got PH30, trucks got PH5, and the medium duty trucks got something that looked like a Thermos.

I imagine GM engineers did some sort of "perfect conditions" calculation that figured a puny filter would do just fine, but the real world stepped in and screwed that up.
 
Yep — was already on XG10575 (one size up) on the old 5.3L and the new 5.3L calls for that so I can buy six packs -
Still looks small but XG’s can last my OLM based OCI with ease …
 
With the same flow, a restriction makes the oil pressure go up. I always thought the main bearings were the most restricted flow point for oil pressure readings. Unless GM has the oil sender before the filter? Then the more restrictive filter would show higher pressure. Maybe the ecore is less restrictive and shows less pressure, measured before the filter?
 
Originally Posted By: goodtimes
With the same flow, a restriction makes the oil pressure go up. I always thought the main bearings were the most restricted flow point for oil pressure readings. Unless GM has the oil sender before the filter? Then the more restrictive filter would show higher pressure. Maybe the ecore is less restrictive and shows less pressure, measured before the filter?


If the PD oil pump is not in relief, the flow is still the same going into the engine even with a more restrictive filter, and the oil pressure will be the same if the sensor is located after the filter. Only time a filter's resistance would influence the pressure gauge on the dash is if the PD goes into relief mode, which means only at high RPM conditions with thick oil.

Yes, if the pressure sensor was before the filter (rarely is), then a more restrictive filter would cause a higher reading on the pressure gauge. It's been discussed before that the typical engine oiling system is about 15 times more restrictive to flow than a typical oil filter (ie, the delta-p across the oiling system is 15 times that across the oil filter).

Originally Posted By: DoubleWasp
That pressure sender is most definitely not before the filter.

+1
 
Don't know if this sender is on the supply or outlet side of the oil filter. Unless the sender is before the filter, so the ecore is less restrictive and shows lower pressure, don't understand the problem. Maybe if the oil pump relief spring is weak it will reduce flow under more restriction by bypassing oil. If sender is before filter, then GM is fixing the problem by putting a more restrictive filter on so the needle moves higher and everyone is happy.

http://ww2.justanswer.com/uploads/Dr/drivefast1971/2013-05-28_221815_1.gif
 
This is where the oil pressure sensor is on the OP's 2010 Silverado 5.3 truck. Located at the top back area of the engine block, which is definitely way after the oil filter. Ref: LINK

 
More info, and this shows the oiling system schematic. Very clear that the oil pressure sensor is way after the filter, and it even shows the pressure sensor "oil filter" (ie, screen talked about that clogs up). - LINK

 
Zee, nice find. According to the article so the link, chances are high the oil pressure sensor is bad. While open that far it makes sense to service the screen / filter under the oil pressure sensor. The author confirms the oil pressure is good with a mechanical gauge. If not good, there are plenty of other opportunities to lose oil pressure.
 
Originally Posted By: DoubleWasp
GM has some wacky rationale for downsizing the filter for the LS engine that they really patted themselves on the back for.

This was mysterious to me, because GM traditionally used the largest filter possible for the application without scraping the ground in the previous generation.

Cars got PH30, trucks got PH5, and the medium duty trucks got something that looked like a Thermos.

I imagine GM engineers did some sort of "perfect conditions" calculation that figured a puny filter would do just fine, but the real world stepped in and screwed that up.


Cost savings is one of many reasons why GM vehicles look so cheap for the past 14-15 years. Smaller filters, no padding on inside door elbow rests.....etc..... c'mon GM.
 
Originally Posted By: ZeeOSix
More info, and this shows the oiling system schematic. Very clear that the oil pressure sensor is way after the filter, and it even shows the pressure sensor "oil filter" (ie, screen talked about that clogs up). - LINK






The active fuel management oil pressure relief valve is interesting, sort of. Don't see the engine oil filter in the schematic. So what is the conclusion then why GM corrects the problem with an oil filter? As you know flow says the same, so it shouldn't matter about the filter unless the sender is before the filter, which it isn't.
 
Originally Posted By: Triple_Se7en
Originally Posted By: DoubleWasp
GM has some wacky rationale for downsizing the filter for the LS engine that they really patted themselves on the back for.

This was mysterious to me, because GM traditionally used the largest filter possible for the application without scraping the ground in the previous generation.

Cars got PH30, trucks got PH5, and the medium duty trucks got something that looked like a Thermos.

I imagine GM engineers did some sort of "perfect conditions" calculation that figured a puny filter would do just fine, but the real world stepped in and screwed that up.


Cost savings is one of many reasons why GM vehicles look so cheap for the past 14-15 years. Smaller filters, no padding on inside door elbow rests.....etc..... c'mon GM.


People buy many GM models because they look expensive, not cheap. The filters aren't small on their small 1.4, 1.5 engines. In fact they seem too large compared to Toyota, Honda, etc. Can't generalize.
 
Originally Posted By: goodtimes
The active fuel management oil pressure relief valve is interesting, sort of. Don't see the engine oil filter in the schematic. So what is the conclusion then why GM corrects the problem with an oil filter? As you know flow says the same, so it shouldn't matter about the filter unless the sender is before the filter, which it isn't.


The "active fuel management oil pressure relief valve" could be defective also. It's there to regulate the oil pressure too, kind of like a secondary pump pressure relief valve. If the AFM relief valve was stuck open some then it would decrease oil pressure at the pressure sensor downstream. Or if the AFM relief valve was intermittently flaky you could see fluctuating oil pressure.

Here's a link that talks about how the oiling system works with the GM AFM engines - LINK

Compare the 3-D sketch in the link to the oiling system schematic posted earlier and you'll see where the oil filter is. The "filter screen" (#4 in the sketch) that gets clogged is shown below the oil pressure sensor (#3 in the sketch) and looks to be there to keep the AFM actuation system clean. I'd think if the screen gets plugged the AFM system doesn't work very well either.
 
ZeeOSix- this is good stuff. Thanks.

The way I read the sketches,
Item #3 Oil Pressure Sensor failure will lead to low pressure readings and maybe a DTC set.
Item #4 AFM oil filter/screen plugging will lead to low pressure readings and maybe a DTC set.
Item #6 AFM regulator valve sticking open will lead to low oil pressure and maybe a DTC set.
Oil pump pressure regulator sticking open will lead to low oil pressure and maybe a DTC set.
O-ring between the oil pump and oil pickup tube leaking air into the oil pump can lead to low oil pressure and maybe a DTC set.
Plugged pickup screen can cause oil starvation, low oil pressure and maybe a DTC set.

Last but not least:
Worn oil pump, low oil pressure,
Worn bearings, low oil pressure.
 
WellOiled - +1, that's how I'd summarize it too. Oil filter as the cause would be even after the worn out bearings IMO. A "more restrictive" oil filter might help to flush out the real root cause, but isn't the root cause IMO.
 
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