Low oil pressure at idle?

-
Cool Hand

Cool Hand

Well-Known Member
Joined
May 13, 2020
Messages
332
Reaction score
438
Location
Middleton Wisconsin
5.7 hemi idle psi is 10 roughly at temp. Goes up to mid forties on throttle. Haven't checked at WOT. Tried putting Rotella in just see if it gained pressure but did not change. Did some reading ,and some people have a low as 6 at idle,and as high as 40+. Question is should I worry,and should I put the 5w20 back in. It did tick on the top end after idling for 20 min with the 5w20 I m it
 
You could go to 30 weight and see if you gain anything.

My old tired 150,000 273 flickers the oilpresure light on 30 weight, on 40 weight, no issue.
 
Gonna raise my target idle up a bit, so it sits at like 15,18 in there somewhere. If the idle was set to 800,to 900 that's where it sits. Any thoughts?
 
Cool Hand said:
Gonna raise my target idle up a bit, so it sits at like 15,18 in there somewhere. If the idle was set to 800,to 900 that's where it sits. Any thoughts?
Click to expand...
What kind of oil filter are you running? Stock? Or remote oil filter? Too small of a shorty filter for clearance can cause this, don't ask me how I know.
 
robcuda said:
What kind of oil filter are you running? Stock? Or remote oil filter? Too small of a shorty filter for clearance can cause this, don't ask me how I know.
Click to expand...
Wix 1516 with a remote relocation kit. It's s standard tall filter,and the remote kit doesn't have any valving. Checked to make sure it wasn't hooked up backwards aswell lol. Couldn't tell ya why I would ever check that
 
Cool Hand said:
Wix 1516 with a remote relocation kit. It's s standard tall filter,and the remote kit doesn't have any valving. Checked to make sure it wasn't hooked up backwards aswell lol. Couldn't tell ya why I would ever check that
Click to expand...
Sure seems like there's a restriction problem. Do you have enough clearance to put a decent size shorty filter on and bypass the relocation kit, just to see the difference?
 
robcuda said:
Sure seems like there's a restriction problem. Do you have enough clearance to put a decent size shorty filter on and bypass the relocation kit, just to see the difference?
Click to expand...
Not a chance. Barely got the remote adapter on with the motor mounts where they are. Seem to be getting plenty volume flowing. Just not building pressure at low rpm. Took it for a test drive today,and it gets over 50 while cruising. Think I'm gonna drain the rotella,and put some new 5w20 back in like it recommends. Everyone says they are finicky about there lubrication. Seemed to improve pressure at idle after the test drive. Sat at about 20 at the stop lights.
 
When changing oil weights does not bring the oil pressure up, it's time for new rod, and main bearings to tighten up the oil film tolerance.

That in turn will keep your oil pressure up at idle.
 
I know some guys like to run the 0w40 in their 5.7 engines.
 
Dana67Dart said:
You could go to 30 weight and see if you gain anything.

My old tired 150,000 273 flickers the oilpresure light on 30 weight, on 40 weight, no issue.
Click to expand...
Wonder if the cam bearings are falling out of it. Seen so many just lose the lead and piss...wait it's not a dinosaur motor.
Check the pump.
 
Last edited:
George Jets said:
When changing oil weights does not bring the oil pressure up, it's time for new rod, and main bearings to tighten up the oil film tolerance.

That in turn will keep your oil pressure up at idle.
Click to expand...
I have a 6.1 that needs a rebuild,and will fit perfectly. Just didn't have time to rebuild it ,and get it to the show on time. I will probably build it how I want and install it later. Just need this one to not tick ,and last a few months
 
So have you tried another gauge or line on it yet?
 
Just keep in mind the old rule of thumb...the engine only needs 10 psi per every 1000 rpm and it will live so, if your idle is 800 rpm then it only needs 8 psi to live at that rpm. The current engine in my Duster really tests that theory throughout the rpm range..lol.. It keeps going!!! It just needs to last until the other engine is ready.
 
Have you changed out to a different oil filter (made sure something else isn't in bypass?). I recently went through this with the Hemi in my wife's durango. I still haven't cut open the filter to see what the deal was but this one filter (the same brand and PN that I always used) was restricting flow.
 
I put a mechanical gauge on temporarily down by filter. Shows about the same as dash. I have changed the filter when I took the Rotella out. Doesn't seem to be making any top end noise with the 5w20 in it. Set my target idle up so it idles around 850, 900. Pressure sits at about 15 to 18 with the idle there. I know the 10 psi for 1000 rpm rule, but I'm used to newly built motors that never run near that low. Just makes me nervous I guess. We have only done a few of these newer motor swaps at the shop. Trying to keep up with the market,and trends and give our customers the options for the newer less maintenance drive trains. Poeple just don't like wrenching like they used too. Just wanna get in ,drive,and feel cool in an old car. We were purely NA here for a long time. I appreciate all the suggestions. Gonna just let her eat for now, and get the 6.1 ready just in case.
BTW I planned on putting the 6.1 in after a rebuild anyway,but this 5.7 pulls pretty hard,and the duster is no slouch for a street car with it.
 
Car headed on the truck to Vegas. Fingers crossed we get to race it after the show! If we do I will definitely post some pics and let yall know how she did.
2021-10-27 14.39.40.jpg
 
I think modern engines with their tolerances and penny pinching emissions dont need much idle fuel pressure. those pumps sap horsepower and every little chance they can get to reduce parasitic loss (electric water pumps, fans...even oil pumps!) they will run the pumps at minimim drag/psi to keep motor happy. as i look ay my 2002 Silverado wirh 134k on the LS motor....28 psi at 600 rpm at 205F.
 
I can tell you the 5.7 is stock form does not like any oil except what the manual says. Had a friend's hemi ticking after an oil change. I told him to change it with the correct weight of oil and its been fine since.
They have also had a lot of problems with oil pumps on these. A friend lost his engine due to a failed oil pump. Do a google search, there are tons of posts about it.
10 psi at hot idle wouldn't be too concerning but I would keep and eye on it.
 
You must log in or register to reply here.
-

Back
Top