Weak oil pressure: change pump or relief spring?
#21
Teching In
Thread Starter
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
yes, there is a cover, which uses the cover and a set of round rubber gaskets to stop the oil. my method is the same as the ones used by Lingenfelter..."m8 alum Alloy High Pressure Blind Sealing Plugs"
Last edited by rcodea; 10-28-2019 at 01:33 PM.
#22
Teching In
Thread Starter
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Always doubt your equipment as well until it proves otherwise. What are you using to read pressure, and from where? Have you tried another gauge?
What about the "barbell", assuming no change, any leaks from that area? Some engines have up to 3 different oil pressure relief valves at various locations. One could be stuck open.
Try a different filter?
What about the "barbell", assuming no change, any leaks from that area? Some engines have up to 3 different oil pressure relief valves at various locations. One could be stuck open.
Try a different filter?
I didnt touch the barbel, the rear cover has not been removed. How do i confirm the barbel is operating correctly? What/where is the third relief valve?
this has been on two different filters which i changed when testing the different oils. I do not think its the filter bypass.
#23
TECH Senior Member
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
The barbell doesn't "operate" . It diverts oil to the filter before going to the rest of the engine. It enabled the block to be drilled with one long passage instead of shorter ones. The barbell effectively breaks the passage into two separate ones.
#24
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Are you running the original valley cover with the DOD stuff on it? You may want to swap valley covers to the old standard valley cover. I did the same thing and had low oil pressure after a DoD delete and it was all because of the valley cover leaking down the oil pressure.
#25
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
I chased down this exact same low oil pressure issue for 3 days until i simply swapped valley covers and immediately it went back to 50+ psi at idle. My readings were the exact same as yours after the delete so I can almost guarantee your leaking oil PSI somewhere on that valley cover. Even if you plugged the valley oil holes the system is still fed by the oil passage that connects to the oil pressure sensor behind the intake manifold.
#26
Teching In
Thread Starter
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
I chased down this exact same low oil pressure issue for 3 days until i simply swapped valley covers and immediately it went back to 50+ psi at idle. My readings were the exact same as yours after the delete so I can almost guarantee your leaking oil PSI somewhere on that valley cover. Even if you plugged the valley oil holes the system is still fed by the oil passage that connects to the oil pressure sensor behind the intake manifold.
I called Lingenfelter who sells the kit mentioned above, they stated that 'usually' the 8 tower plugs is all that is needed. It was less than definitive to me, so started researching the oil passage at the pressure sender you mentioned...i was not aware that there is a oil supply going to through the valley cover to the solinoids. This is probibly common knowledge to most, and since most people just replace the valey cover, it doesnt get mentioned often that this oil passage in the valley cover itself needs to be plugged as well.
So, local dealer has the $60 GMPP 12598832 on hand. I'll throw it on tonight and give it a start. Course, I am mid way through swapping the oil pump, so no water or water pump, engine is lifted from its mounts, the crank bolt is loose, and I have no oil in it. I'll refill and try for a few seconds and see where it is just after startup.
I will report back.
Also, this begs the question...assuming the valley cover fixes my issue, should i still proceed with swapping the M295 for the M365....or leave it as is and forget about the M365 pump?
Last edited by rcodea; 10-28-2019 at 01:58 PM.
#27
Teching In
Thread Starter
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
So I replaced the valley cover as above. looks like i am getting ~3psi higher at the same idle speed and similar coolant temps(77 vs 81)...just after cold start with idle stabilized. Up from 38psi to 41psi.
so, back to the same question as before, swap the M295 for M365?
any input before i start that tomorrow?
so, back to the same question as before, swap the M295 for M365?
any input before i start that tomorrow?
#28
Moderator
iTrader: (4)
Join Date: Jul 2014
Location: My own internal universe
Posts: 10,446
Received 1,838 Likes
on
1,146 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by rcodea
no i did not measure the bearing clearances...i checked the surfaces and moved on. So i assume the clearances are on the large side of spec. No, i have no way to measure them, nor interest in pulling the motor and rebuilding it at this time. it ran well before the DoD delete and swapping from the stock oil pump to the M295.
i did not confirm the pickup to pan clearance...the pickup is supplied by holley with their pan, so i assumed it was to spec. will confirm when i have the pan off again for the pump change.
i did not confirm the pickup to pan clearance...the pickup is supplied by holley with their pan, so i assumed it was to spec. will confirm when i have the pan off again for the pump change.
#29
Teching In
Thread Starter
#30
Moderator
iTrader: (4)
Join Date: Jul 2014
Location: My own internal universe
Posts: 10,446
Received 1,838 Likes
on
1,146 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by rcodea
i currently have 10w40 in it now, up from the normal 5w30 that is standard with this motor.
#31
Teching In
Thread Starter
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Update:
Replaced the M295 with the M365 pump this weekend. Initial turnover to prime netted exactly 50 psi, which i assume is from the relief valve internal to the pump regulating the pressure there. This is up from 33psi highest using the same 10w40 oil.
upon cold start, it settled at 55psi idling at 67*F at 1100rpm.
No hot numbers yet, but i will say the engine already sounds better than before....the upper end noise is already noticeably quieter.
Replaced the M295 with the M365 pump this weekend. Initial turnover to prime netted exactly 50 psi, which i assume is from the relief valve internal to the pump regulating the pressure there. This is up from 33psi highest using the same 10w40 oil.
upon cold start, it settled at 55psi idling at 67*F at 1100rpm.
No hot numbers yet, but i will say the engine already sounds better than before....the upper end noise is already noticeably quieter.
#32
Moderator
iTrader: (4)
Join Date: Jul 2014
Location: My own internal universe
Posts: 10,446
Received 1,838 Likes
on
1,146 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Glad you got it sorted. When will you go kill mustangs?
#33
Teching In
Thread Starter
#34
Moderator
iTrader: (4)
Join Date: Jul 2014
Location: My own internal universe
Posts: 10,446
Received 1,838 Likes
on
1,146 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
#36
Moderator
iTrader: (4)
Join Date: Jul 2014
Location: My own internal universe
Posts: 10,446
Received 1,838 Likes
on
1,146 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
I think we live three hours apart. I was curious.
#37
Teching In
Thread Starter
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
just to close the loop on this.
I have got the truck back on the road and with one heat cycle on it. with the 10w40 oil in it, my idle pressure is ~42psi, and cruise is around 50psi. I havnt done a full throttle pull yet, but aggressive accel at 3krpm showed about 65psi.
also of note the engine is much more quiet overall with only some minor top end noise. I am now convinced that my knocking issue was a low oil pressure condition and not bad bearings.
I will likely go back to 5w30 oil on the next oil change and see where that nets me, and also watch the oil pressure during some high rpm pulls to make sure i am not starving the oil pan or pickup
Hopefully this helps someone else is the future.
I have got the truck back on the road and with one heat cycle on it. with the 10w40 oil in it, my idle pressure is ~42psi, and cruise is around 50psi. I havnt done a full throttle pull yet, but aggressive accel at 3krpm showed about 65psi.
also of note the engine is much more quiet overall with only some minor top end noise. I am now convinced that my knocking issue was a low oil pressure condition and not bad bearings.
I will likely go back to 5w30 oil on the next oil change and see where that nets me, and also watch the oil pressure during some high rpm pulls to make sure i am not starving the oil pan or pickup
Hopefully this helps someone else is the future.
#38
TECH Fanatic
iTrader: (5)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
It’s been said by more than a few engine builders that you only need 10lbs oil pressure per thousand rpm, not sure if they meant that to be true at idle as well. They look at excess oil pressure as a power robber. The melling 10296 as stated early in this thread is a good way to go if your motor is built with extra bearing clearance.
Last edited by 64post; 11-23-2019 at 02:06 PM.
#39
TECH Senior Member
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
It’s been said by more than a few engine builders that you only need 10lbs oil pressure per thousand rpm, not sure if they meant that to be true at idle as well. They look at excess oil pressure as a power robber. The melting 10296 as stated early in this thread is a good way to go if your motor is built with extra bearing clearance.