5.3 Oil Pressure "weird" Issue

Ron

Ron

Dum Spiro Spero
Moderator
Joined
Apr 16, 2005
Location
Sharon, SC
Was driving one of the company suburbans this am. Its either a 13 or a 14.
5.3 with AFM. ~150k miles.

Driving along all is well and idiot light warning says
"Low Oil Pressure Stop Engine NOW"
Check the gauge and its on zero. Pull over, shut her down and check oil(fleet vehicle), its full.
Decide to start it back up and see if its throwing nay oil up the dipstick. Start back up pressure gauge comes back and oil pump is definitely working.

Nervously carry on 50+ miles to the destination with a few more oil level checks and watching the gauge and all appears normal.

Not really sure if its a sensor issue, or wondering if its possible something plugged the pickup and shutting it down allowed it to clear. Worth mentioning that the battery died in last Friday and put a new battery in it right before begining this trip where this happened. Double checked and dont see any way we could have dislodged a sensor in the area or hit a harness clip etc...but figured it was worth mentioning.


Anyone had anything similar?
 
Seen the sensors act up on the like 00-10s sometimes, never had one that new though. A little piece of gunk get stuck in the pressure sensor and causes it to not work.
 
The AFM is a real piece and known for issues. I’d say it’s likely your AFM relief valve in the oil pan acting up, this causing low oil pressure.

new senders are cheap and easy to check and change. Don’t forget the screen as it can cause issues as well. Also, make sure you have the correct oil filter. Cheap filters don’t let oil pressure build like it’s supposed to and can cause a p0521 code.

I just went through a $4500 AFM fix on the wife’s 6.2 in her Yukon XL; thankfully it was under warranty.
 
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I replaced the screen and sensor on our '07 5.3 suburban recently, it had the same symptoms. I expect to eventually do it on our recently aquired '11. Seems like a common prob from looking around the boards and such.
 
rockcity said:
The AFM is a real piece and known for issues. I’d say it’s likely your AFM relief valve in the oil pan acting up, this causing low oil pressure.

new senders are cheap and easy to check and change. Don’t forget the screen as it can cause issues as well. Also, make sure you have the correct oil filter. Cheap filters don’t let oil pressure build like it’s supposed to and can cause a p0521 code.

I just went through a $4500 AFM fix on the wife’s 6.2 in her Yukon XL; thankfully it was under warranty.
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AFM and the stupid high prices of them used trucks is why I bought a 98. I'm no expert but I assume that 75% of the trucks I saw for sale on CL and other sources had AFM/oil issues.
 
On older 5.3, I have seen sludge cause similar issues. Not saying it couldn't be afm relief etc, I don't see much "new" stuff. Although if it's sludge, if you cut it off and restart, I'd expect the issue to reoccur in 15-20 minutes of operation. I've seen plenty of failed oil sending units. Of course knocking is a definite indication of low pressure, but by then it's already damaging components as you know. Just some thought food. If it was bought new and maintenanced, you can probably rule out sludge. Ones I've run into with sludge either a) purchased used with 100k+ or b) never maintenanced.
 
It’s been a fleet vehicle so maintenance is .... iffy.
But we’ve put2,300 miles since the incident and gasnt reoccurred.
Getting serviced Monday will see what oil looks like
 
Strain the oil and see if there's any small particles.. I've seen oil look clean and pan be sludged with a groove cut in it from draining.. should be able to check that with a screw driver through the drain hole.
 
rockcity said:
The AFM is a real piece and known for issues. I’d say it’s likely your AFM relief valve in the oil pan acting up, this causing low oil pressure.

new senders are cheap and easy to check and change. Don’t forget the screen as it can cause issues as well. Also, make sure you have the correct oil filter. Cheap filters don’t let oil pressure build like it’s supposed to and can cause a p0521 code.

I just went through a $4500 AFM fix on the wife’s 6.2 in her Yukon XL; thankfully it was under warranty.
Click to expand...

this. dont ever drive an AFM/DoD engine with low oil pressure. it causes a lifter to drop and the only fix is a $5k tear down of the top end. learned that the hard way.



Do check the screen at the oil sending unit. they get clogged and the clog can shift in and out causing the issue to come and go. also, go ahead and start thinking oil sending unit just to be safe. if you havent already done the damage that will keep it from happening.

the AFM/DoD failures stem from faulty oil sending units and or clogged screens. if you do end up with a failure it will return and pretty quickly if those two issues arent addressed. dont wanna fix that twice!
 
Reid said:
this. dont ever drive an AFM/DoD engine with low oil pressure. it causes a lifter to drop and the only fix is a $5k tear down of the top end. learned that the hard way.



Do check the screen at the oil sending unit. they get clogged and the clog can shift in and out causing the issue to come and go. also, go ahead and start thinking oil sending unit just to be safe. if you havent already done the damage that will keep it from happening.

the AFM/DoD failures stem from faulty oil sending units and or clogged screens. if you do end up with a failure it will return and pretty quickly if those two issues arent addressed. dont wanna fix that twice!
Click to expand...


And if the damaged lifter cannot be removed from the block, the block has to be replaced. Not cheap!
 
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