slow oil pressure [Archive] - Duramax Diesels Forum

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febreze101
09-13-2016, 04:42 PM
Question can't find any answers on this on any of the sites but usually 1 out of 5 cold starts my oil pressure is slow to come up about 4 to 5 seconds before it builds pressure what could this be? Its almost like when you change ur oil and theres that delay when you first fire it back up. The truck is a 2011 LML

drmax07
11-29-2016, 10:43 PM
I've noticed this a few times on mine, but never found a fix.

chevyburnout1
12-01-2016, 07:26 PM
I've had the same concern after my two engine builds. Sometimes it's fast, other times it's super delayed, and sometimes it doesn't move and sets an oil pressure circuit code.

stibuilder
08-16-2018, 10:45 AM
Bumping this thread because im seeing the same thing.

chevyburnout1
08-16-2018, 11:08 AM
My one input since I commented originally. A few of my tunes had a slightly lower idle speed, especially on start up. If I run a tune that has a stock idle speed right at start up the oil pressure builds every time and has never set the oil pressure sensor code since.

kidturbo
08-16-2018, 03:52 PM
I haven't tested on an LML, but on LBZ/LMM oil pressure CANbus msg to BCM is buffered, and only registers down about 25psi. The buffering looks to be meant for limiting jumps or swings.

Testing on bench I noticed dash drops from 25 straight to zero, while EFI live reads correctly below 25. So I'd check it on start up against EFI or Tech2 and see if that logic fits.

-K

stibuilder
08-16-2018, 09:17 PM
I haven't tested on an LML, but on LBZ/LMM oil pressure CANbus msg to BCM is buffered, and only registers down about 25psi. The buffering looks to be meant for limiting jumps or swings.

Testing on bench I noticed dash drops from 25 straight to zero, while EFI live reads correctly below 25. So I'd check it on start up against EFI or Tech2 and see if that logic fits.

-K

I have an aftermarket sending unit in the cylinder right before the oem sending unit and it also reads zero and moves exactly when the dash starts to. Both are zero then then start swinging up quickly but its the pause at zero that has me wondering whats up. After they are up the thing has great oil pressure even when hot, always above 50+ at 2000rpm on the freeway even when the oil is at its max temp. It also does the 20psi dead nuts when hot at idle.

The idle rpm could be a tad low its showing 500 on the dash.

2004LB7
08-16-2018, 10:32 PM
What about the oil filter anti drain back valve? Have you tried changing the filter?

stibuilder
08-16-2018, 11:14 PM
What about the oil filter anti drain back valve? Have you tried changing the filter?

Had a Napa gold in it now, and it has the Mocal oil cooler adapter, this could be causing the slow down on the pressure response but its supposed to be closed until 180 degree's. Just picked up a K&N filter for it going on with fresh oil this weekend. Ill report back.

TheBac
08-17-2018, 03:48 AM
Anything K&N on these engines is a really bad idea. Just my .02.

NC-smokinlmm
08-17-2018, 03:53 AM
I had low and slow pressure in the 5.3, switched to GM filter and bam dead nuts perfect...

Awenta
08-17-2018, 06:51 AM
I had low and slow pressure in the 5.3, switched to GM filter and bam dead nuts perfect...



Yeah I usually stick to delco filter as well. Or mobil.


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stibuilder
08-17-2018, 09:21 AM
Sounds easy enough to grab a GM filter today. Using DELO 400 15w40

THEFERMANATOR
08-17-2018, 11:01 AM
I've been running wix premium xp filters, and I've been getting slow to build quite often as well. I mayvtry a GM filter next.

zakkb787
08-17-2018, 11:40 AM
Can’t help but wonder if it’s because the wix and Napa filters have thicker elements making it harder for the pump to push thru at initial startup

NC-smokinlmm
08-17-2018, 01:38 PM
I believe it's associated with pop off pressure of bypass, the filter volume and media will change it...

Chevy1925
08-17-2018, 08:41 PM
The bypass is on the pass side in the other oil galley. Won’t be affect by oil filter type

kidturbo
08-17-2018, 11:01 PM
Some filters have a pressure bypass built in. But doubt that's issue. Sounds like a drain back, try a different filter.

stibuilder
08-17-2018, 11:27 PM
Filter that was on the truck was a Rotella, looks like the holes in it are much larger and oval compared to the circular ones of the new GM filter. Post oil change the oil pressure was about 10psi higher. Going to see how it starts in the morning and see if I get any change. I kept a sample of the oil ill send out to see if there is any metal in it and go from there. Ill post a picture of all the filters later on Saturday.