- Joined
- May 9, 2023
- Messages
- 111
So you’re back down to 26-27?
Oil change resolved hot idle lower oil pressure., why?
- Thread starter Cmobile
- Start date
Yea still about the same.
Engine is smooth, no tics, no taps, no unusual noise of any kind. (I even turned hy hearing aids up all the way to listen
) not even on cold start up.
This may not be a problem per se' other than its getting long in the tooth.
Will change the oil filter with AC Delco, quick drive and see what happens.
Then maybe put the warmed vehicle on a hill nose down, add extra oil and see.
Engine is smooth, no tics, no taps, no unusual noise of any kind. (I even turned hy hearing aids up all the way to listen
) not even on cold start up.This may not be a problem per se' other than its getting long in the tooth.
Will change the oil filter with AC Delco, quick drive and see what happens.
Then maybe put the warmed vehicle on a hill nose down, add extra oil and see.
Put the PF48 on. Drove to town and back.
Lowest pressure ive seen so far.
Edit:
This could simply be the new Oil Sending Unit. Perhaps I didn't get all the oil out of the connector, from the old OSU that leaked oil into the electrical side, engine oil temps may have been warmer than previous observations. Etc.
Disclaimer:
I'm not saying one filter is better than another, I am only sharing my results. Too many variables in my non-scientific methods. Differences should be considered noise.
Next step is possibly the pickup O-ring test.
YMMV
Lowest pressure ive seen so far.
Edit:
This could simply be the new Oil Sending Unit. Perhaps I didn't get all the oil out of the connector, from the old OSU that leaked oil into the electrical side, engine oil temps may have been warmer than previous observations. Etc.
Disclaimer:
I'm not saying one filter is better than another, I am only sharing my results. Too many variables in my non-scientific methods. Differences should be considered noise.
Next step is possibly the pickup O-ring test.
YMMV
Last edited:
That is not too terribly different from what our car has always done. With hot oil it usually runs 20 psi idle and a touch under 40 cruising. Cold pressures are about 15 psi higher.
Last edited:
Tried the nose-down overfill method to check pickup tube O-ring. 2.5 quarts over filled. No change in pressure. Incline in my driveway is pretty steep. Tried nose up, and nose down a few times. No change either way.
Gonna be traveling this weekend, so I drained the oil, put in M1 0w40 FS Euro and a Fram Endurance. Oil pressure maybe just over 30psi hot idle.
Here are pics from inside the pan with boroscope cam. Not great pics, but it's a $30 cam, what can I say?
Went in through the drain plug hole.
Thank you all for sharing your thoughts, wisdom, points to ponder and ideas.
Happy New Year!
~C
Gonna be traveling this weekend, so I drained the oil, put in M1 0w40 FS Euro and a Fram Endurance. Oil pressure maybe just over 30psi hot idle.
Here are pics from inside the pan with boroscope cam. Not great pics, but it's a $30 cam, what can I say?
Went in through the drain plug hole.
Thank you all for sharing your thoughts, wisdom, points to ponder and ideas.
Happy New Year!
~C
Last edited by a moderator:
Update,
Watched a few YouTube videos about AFM cyl deactivation.
At the advice of a youtuber, I checked the VLOM manifold bolts to see if they were loose. The front two are easily accessible. Sure enough, they were very loose. I could tighten them 2 turns with my hand.
I tightened the two I could reach, and Voila! Oil pressure is back. I need to remove the intake plenum/manifold to check the rest, but oil pressure returned to 36-37ish.
If the VLOM manifold bolts are loose, the O-Ring seals underneath won't seal properly.
Watched a few YouTube videos about AFM cyl deactivation.
At the advice of a youtuber, I checked the VLOM manifold bolts to see if they were loose. The front two are easily accessible. Sure enough, they were very loose. I could tighten them 2 turns with my hand.
I tightened the two I could reach, and Voila! Oil pressure is back. I need to remove the intake plenum/manifold to check the rest, but oil pressure returned to 36-37ish.
If the VLOM manifold bolts are loose, the O-Ring seals underneath won't seal properly.
Last edited:
- Joined
- May 9, 2023
- Messages
- 111
Well that’s great news…..good to hear you have it sorted.
Yes it does.
Grimy indeed
Idling at 550 RPM. Seems low
After tightening the 2 loose front bolts on the VLOM, the oil pressure is back to 37ish PSI.
I only tightened the two in front that were accessible, anf it helped a lot.
Plan to pull the intake manifold and check the rest of the bolts on the VLOM. Replace the seals.
Definitely check the two accessible bolts to see if they are loose.
The 2 bolts that were finger loose were left side of the "top pic".
I only tightened the two in front that were accessible, anf it helped a lot.
Plan to pull the intake manifold and check the rest of the bolts on the VLOM. Replace the seals.
Definitely check the two accessible bolts to see if they are loose.
The 2 bolts that were finger loose were left side of the "top pic".
It sounds like you've found an issue, but...
I wouldn't get too spooked by any reading that comes from GMT 400/800/900 cluster gauges. It's well established that GM does some data smoothing and nonlinearity of gauges to keep the driver calm. Nor does GM necessarily put the needles onto the stepper from one vehicle to the next. (Take internet info on pressure with a grain of salt.) If you really care about deltas smaller than 5 psi or 15 F, a digital readout like a scanguage is a worthy investment.
When I did the pickup oring in my 5.3, it wasn't that it was out of the bore, it was that it had softened and contracted over time. I'm not sure if that's what you were trying to see with the borscope or not.
I wouldn't get too spooked by any reading that comes from GMT 400/800/900 cluster gauges. It's well established that GM does some data smoothing and nonlinearity of gauges to keep the driver calm. Nor does GM necessarily put the needles onto the stepper from one vehicle to the next. (Take internet info on pressure with a grain of salt.) If you really care about deltas smaller than 5 psi or 15 F, a digital readout like a scanguage is a worthy investment.
When I did the pickup oring in my 5.3, it wasn't that it was out of the bore, it was that it had softened and contracted over time. I'm not sure if that's what you were trying to see with the borscope or not.
The filter you posted appears to be quite dirty. I would suggest changing the filter halfway through the oil change interval for a while if you are using an oil that has cleaning properties, Havoline Pro DS included. I would do this until the filters are not black anymore. My preference for filters would to be ditch the Delco's always seem cheap and flimsy . Although you have identified the psi problem, it seems that there is still some cleaning going on based on the condition of the filter. It's a shame that you had to switch from Havoline oil early, as it is a very good oil. Thank you for sharing the pictures in the post, they are quite interesting.
Similar threads
