5.3/6.0 GM V8s plugging up oil filters, oil pressure dropping to near zero. Why doesn't the oil filter bypass valve open preventing the drop in oil pressure?
Hello, Roy Gage from Estherville Iowa where I run a small automotive repair shop. I will tell you what I know, what I think I know, what I think I do not know and then hopefully someone here can enlighten me.
Couple months ago we had a 6.0 ¾ ton GM pickup in with about 195K on the odo. Ran nice, engine sounded solid. Complaint, low and at times no oil pressure. Oil pressure gauge in the dash was slow to come up and at times would drop to near zero. We replaced the oil sender, located behind the intake, and the small screen under it. No difference. We had previously swept test the oil gauge and knew it was working well.
Replaced the customers PF48e AC Delco filter with a wix 57060, changed oil to 5/30 Dexos and all is well. Twenty plus lbs. hot idle, 40 plus lbs. down the road hot.
Pulled the old oil filter apart. On one end of the pleats some sludge back about a ¼ inch back up from the end. The rest of the filter appeared good but when dragging a finger nail down between the pleats you could feel some carbon grit. To my mind this filter was not plugged to the point of restricting oil flow. I do now believe that it was.
The customer had replaced the filter a month before then went on a two week vacation leaving the truck at home. Point is there were not that many miles on the oil and filter. If it was plugged it was simply because there was enough grit floating around in the motor to get swept up and into the filter. Customer told us he has used the oil life monitor for his change intervals since he purchased truck new.
I contacted our AC Delco vendor whose manager told me another shop in town had trouble with the PF48E doing the same thing. He also reported he had trouble with them plugging up twice on his own truck. Sending a couple in to Delco he got back a report that there was no problem with the filters although I believe they must have told him they were plugged up as when the manager told him the Wix resolved the problem the Delco fellow said, rather sarcastically, to be sure to give him a call when his Wix plugged up.
Found a lot of reports of others having the issue. Getting 2 or 3K on a change and then the oil pressure getting soft. At the time I blamed the Delco filters assuming they had a bypass valve that simply was not opening up. I also blamed, and still do that GM simply did not put a large enough filter on these motors to run extended oil changes and also that the extended oil changes were causing a carbon buildup in the motors.
Victim number two. 2009 GM pickup with a 0 code 5.3. 160K on the odo. 7000 miles on a dexos oil change. Runs and sounds solid. Pretty much zero oil pressure at all times. Put on a sender and the screen below it, oil pressure slow to come up on start up but then OK. Took for test drive and pressure dropped to near zero after several blocks. Dropped oil and filter. Should note this one was equipped with a WIX 57060. everything is fine. Hot idle, 32 lbs. Down the road hot, 42lbs. In passing gear hot, 52 lbs.
Cut the Wix apart. No sludge on the end as the Delco had, same light grit in the pleats. Again although this filter was dropping the oil pressure to near zero had someone asked me if it was plugged enough to drop the pressure before I ran into this problem I would have told them no. I have read some posts here about people reporting what their filters look like inside after 10 or 15 k and basically saying they look great. I will point out that after looking at these two filters, I would not be so sure about that.
My burning question, which Wix's hotline was unable to answer and the technical hotline I use was unable to answer is simply, how could the filter's bypass valve not open? With forty lbs. plus on one side of the filter media and next to zero on the other how could a bypass valve Wix says is set at 12 lbs. not open and balance the pressure?
Had you asked me before these two trucks I would have told you with the greatest of authority that upon the oil filter plugging the bypass valve would open and the event would be so seamless that you by watching the gauge would not be aware of it happening. Now I simply scratch my head.
Yesterday I went to an evening clinic. Lots of techs there, most had ran into the problem. None had an idea of why the relief valve was not working as I thought it should.
There is a SI bulletin from GM, #PIP5276D which tells you if you run into this problem, it will also set a code P0521,to upgrade to a UPF48R filter. I would be interested in what the difference is between the this number and the PF 48E.
Now you know what I do and don't know, enlighten me. Thank you in advance for any insights. If I missed a pertinent discussion on the subject in the archives I apologize for the rehash.
5.3& 6.0 GM trucks losing oil pressure PF48E
- Thread starter roygage
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That’s interesting … on/off the fence myself on this subject …
This morning I was advising my wife to take it slow a few blocks in the Tahoe as I prefer using the XG10575 while I followed along with “pings” coming in. I have 6 PF63e’s and 7 XG10575’s ... one M1 and one Wix and none are the “ideal” filter …
IIRC there were also issues with an O ring for the Pickup tube. Not exactly sure what its all about but worth looking into.
Trav. Yes,they have trouble with the pickup tube 0--ring. I have not ran into one yet, or perhaps just have not recognized one. A fellow tech gave me a good tip on how to determine if the o-ring is letting air draw in. Add three quarts of oil, if the issue goes away it is because three quarts raises the level enough to cover the o-ring and the air can no longer be drawn in. Should note this is only for testing purposes.
The same tech, he works at a GM dealer, told me there is a pressure relief valve in the oil pan which limits oil pressure to 55 lbs.
Both of the trucks we had trouble with are doing well after changing the filters, have had a couple people tell me thy have had the problem on much lower mileage units.
I’m thinking if it’s not the screen giving you a bogus oil pressure then it’s a real oil pressure problem, caused by the brittle O ring at the pickup tube. You would have to drop the pan. If you do, please let us know if that corrected it. I’m thinking other issues are seperate. Have to admit, I’m puzzled by the grit, unless something happed to the pickup tube and somehow it’s picking up fluid from the bottom of the pan.
For what it’s worth, I have a similar hot oil idle pressure on a 2008 6 liter with 40 psi at hot highway speed with a Fram Ultra.
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We have a 200k mile 6.0 in a 3500 savanna that runs 44 psi highway and about 20 idle when hot. Super quiet and smooth.
Just about every other one here and those I can remember run about the same at idle but 50-60 on the highway. I remember one that ran 80 when cold!
The only oil pressure related failure we have ever had in our fleet was caused by the pressure relief check valve sticking in the bore in the pump.
Note that the low oil pressure spec for these used to be 6 psi IIRC...
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Originally Posted By: roygage
Snagglefoot. It is the filters. Replacing them resolves the issue. Yes, there can be other sources of oil pressure trouble on these motors.
My 6.0 lq9 does not like the Fram Ultra. The "piston slap" and lifter ticks have almost entirely disappeared switching to a less efficient filter. So there is some truth.
Normally I wouldn't pay much attention to stuff like this but had a interesting experience with an AC Delco filter this week actually.
Friday evening changed the oil on my dad's F150 5.0 using an AC Delco PF63E. Previously had only used Wix/Napa Gold or Fram XG but I think Walmart was out the day I went to pick up a Fram and the PF63 cross references. He called me Wednesday saying he was getting low oil pressure warning and asked what kind of oil I put in it. I told him try a different filter and he picked up a Wix from the local auto parts store. Hasn't had an issue since.
Originally Posted By: Snagglefoot
For what it’s worth, I have a similar hot oil idle pressure on a 2008 6 liter with 40 psi at hot highway speed with a Fram Ultra.
Originally Posted By: demarpaint
If that's hot idle oil pressure what's the problem? If the gauge is working properly that's fine. I would get a reading from a mechanical gauge if you have any concerns. 20 psi or over at a hot idle is good. 40 psi hot on the highway should be good too, but I'd double check that with shop manual.
There is no logical reason since the bypass should open and the pump should pump a positive volume of oil.
But I had the same thing happen on my work truck. I changed the PF48E to a Wix 57060 and fresh oil and all has been well for around 4000 miles. '10 5.3 with 127k. Still watching it to see if it is the o-ring. Not sure how a filter can do that, but in my case it does appear to be the filter also. I have changed the oil with around 30% left most times (5-7k) but switched from semisyn to Dexos 2 years and 30k ago and did go to 0% a couple times - 10k miles.
If a filter is full, even with an open bypass valve it may not be flowing enough to keep the relief valve in the oil pump from opening, if the relief is defective and opening too soon. Combine that with 195K and maybe some bearing clearance, the oil pressure goes down. A test of the 48e would have been to put a new 48e on instead of a different make. Fram makes racing filters and one feature is a high flow bypass valve.
Originally Posted By: SteveSRT8
Originally Posted By: demarpaint
If that's hot idle oil pressure what's the problem? If the gauge is working properly that's fine. I would get a reading from a mechanical gauge if you have any concerns. 20 psi or over at a hot idle is good. 40 psi hot on the highway should be good too, but I'd double check that with shop manual.
After cutting the problem filter apart, did you examine the bypass valve to see whether it was defective somehow? I don't see any other explanation.
Where can so much "grit" be coming from? I never find much visible in filters except a few tiny carbon particles, and only occasionally a shiny speck.
No issues here to report but the 4.8L Silverado I drive for work most days with 180k miles and 7300 hours runs about 50-60psi on the highway and 30psi at idle. Never anything funny with the oil pressure. Longest it goes on an oil change is probably 5k though. Last oil change I converted it to synthetic though.
CR94, I did not see anything out of sorts with the by-pass valves on either trucks. As far as where all the carbon grit came from. I need to make the point that the filter was not loaded with it. Had someone brought the element to me and asked if I thought it was plugged I would have replied, no, it was not.
The carbon grit was small particles which I could pickup running my finger down the pleat after I had opened it up. My best guess is it is from carbon buildup/coking on the inner block which broke loose and got into the oil. Sometime you see a older motor get a bunch of fuel into it due to leaking carb. or fuel pump and the fuel in the oil will break loose carbon from the inside of the engine. I saw no sign of fuel in the oil on these two trucks.
Again I point out, visually, the filter media did not look like it was plugged. I also point out that although these are the first two I have seen or been aware of the more I poke around on other sites and google it is not at all uncommon.
