Low oil pressure at idle

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Spetz

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I installed an oil pressure gauge and at idle with warm oil it sits at 15psi.

The engine is a rebuilt 6A12 Mitsubishi.
Oil pressure when cold is high (55psi or so) and when revved warm it goes to 150psi.

I understand the high pressure could be the pressure relief valve but what is the low idle pressure attributed to?
 
Originally Posted By: dishdude
15 at warm idle isn't low.


I wouldn't disagree that it is within spec. Do I like to see that on a fresh engine....No!

I wonder if the PR valve is stuck? Or just a sloppy build with a heavy PR spring or a shimmed stock spring?
 
Would a pressure relief valve (whether heavy spring or shimmed stock spring) cause low idle pressure?
 
Originally Posted By: Spetz
Would a pressure relief valve (whether heavy spring or shimmed stock spring) cause low idle pressure?


Mitsubishi engines just aren't the best and typically have low oil pressure at idle, it wasn't uncommon to see them tripping low oil pressure warning lights set at 7-8 PSI when they get 50-60k miles on them.
 
Originally Posted By: dishdude
Originally Posted By: Spetz
Would a pressure relief valve (whether heavy spring or shimmed stock spring) cause low idle pressure?


Mitsubishi engines just aren't the best and typically have low oil pressure at idle, it wasn't uncommon to see them tripping low oil pressure warning lights set at 7-8 PSI when they get 50-60k miles on them.


Which Mitsubishi engines have you seen do this? I was a mechanic at a Mitsubishi dealer in the early 2000's and never came across this issue.
 
Originally Posted By: hpb
Originally Posted By: dishdude
Originally Posted By: Spetz
Would a pressure relief valve (whether heavy spring or shimmed stock spring) cause low idle pressure?


Mitsubishi engines just aren't the best and typically have low oil pressure at idle, it wasn't uncommon to see them tripping low oil pressure warning lights set at 7-8 PSI when they get 50-60k miles on them.


Which Mitsubishi engines have you seen do this? I was a mechanic at a Mitsubishi dealer in the early 2000's and never came across this issue.


I've seen it frequently with 1.8/2.0 engines in Eclipses and 2.5/3.0 V6s. Here in the states a lot of Chrysler vehicles were offered with Chrysler made engines and Mitsubishi engines. The Chrysler engine always proved to be more reliable.
 
Originally Posted By: dishdude
Originally Posted By: hpb
Originally Posted By: dishdude
Originally Posted By: Spetz
Would a pressure relief valve (whether heavy spring or shimmed stock spring) cause low idle pressure?


Mitsubishi engines just aren't the best and typically have low oil pressure at idle, it wasn't uncommon to see them tripping low oil pressure warning lights set at 7-8 PSI when they get 50-60k miles on them.


Which Mitsubishi engines have you seen do this? I was a mechanic at a Mitsubishi dealer in the early 2000's and never came across this issue.


I've seen it frequently with 1.8/2.0 engines in Eclipses and 2.5/3.0 V6s. Here in the states a lot of Chrysler vehicles were offered with Chrysler made engines and Mitsubishi engines. The Chrysler engine always proved to be more reliable.


Well there you go, that's a new one on me! Thanks
smile.gif
 
What oil weight are you running?

For comparision, according to my factory service manual, when oil (5w30) temperature is between 75ºC - 90ºC, minimum oil pressure for a 6G72 12-valve is 80 kPa (12 PSI). My actual oil pressure at idle between 75ºC - 90ºC, running 15w40, is 289 kPa (42 PSI).
 
Originally Posted By: dishdude
Originally Posted By: Spetz
Would a pressure relief valve (whether heavy spring or shimmed stock spring) cause low idle pressure?


Mitsubishi engines just aren't the best and typically have low oil pressure at idle, it wasn't uncommon to see them tripping low oil pressure warning lights set at 7-8 PSI when they get 50-60k miles on them.
Yeah whenever I see a car pulling away from a light puking blue smoke it's almost always a Mitsubishi.

150 psi oil pressure when revved? Uh?

But 15 doesn't sound that bad.
 
Originally Posted By: Nick1994
Yeah whenever I see a car pulling away from a light puking blue smoke it's almost always a Mitsubishi.


The Mitsubishis you get in the US are obviously different to the ones we get here...
 
Originally Posted By: hpb
Originally Posted By: Nick1994
Yeah whenever I see a car pulling away from a light puking blue smoke it's almost always a Mitsubishi.


The Mitsubishis you get in the US are obviously different to the ones we get here...


Please tell them to stop dumping their rubbish here!
 
Mitsubishi engines can't be too bad, though I wish they were they never would have bombed pearl harbor
 
Originally Posted By: Spetz
I installed an oil pressure gauge and at idle with warm oil it sits at 15psi.

The engine is a rebuilt 6A12 Mitsubishi.
Oil pressure when cold is high (55psi or so) and when revved warm it goes to 150psi.

I understand the high pressure could be the pressure relief valve but what is the low idle pressure attributed to?

I would check the accuracy of your gauge. I doubt your reaching 150 psi.
 
Originally Posted By: dishdude
Originally Posted By: hpb
Originally Posted By: dishdude
Originally Posted By: Spetz
Would a pressure relief valve (whether heavy spring or shimmed stock spring) cause low idle pressure?


Mitsubishi engines just aren't the best and typically have low oil pressure at idle, it wasn't uncommon to see them tripping low oil pressure warning lights set at 7-8 PSI when they get 50-60k miles on them.


Which Mitsubishi engines have you seen do this? I was a mechanic at a Mitsubishi dealer in the early 2000's and never came across this issue.


I've seen it frequently with 1.8/2.0 engines in Eclipses and 2.5/3.0 V6s. Here in the states a lot of Chrysler vehicles were offered with Chrysler made engines and Mitsubishi engines. The Chrysler engine always proved to be more reliable.


Were the turbo Chryslers from the 80s-90s Mitsubishi engines?
 
I am running 5W40 Shell Helix Ultra in it.

The engine is in a car that is only used for track racing.
Is the current oil pressure an issue or doing damage to the engine?

I haven't seen it go to 150psi but it is at 130psi well before redline (I haven't revved it to redline with the gauge yet so 150psi was an assumption)

How can I test the oil pressure gauge for accuracy?
 
Don't worry about idle/ low rpm pressure below 1000 rpm . No load on engine. Oil pump is there to put oil in the bearing not to float the crank. Does this motor have HLA or SUB valvetrain?

If the machine shop opened the main rod or cam bearing clear another .0005 -.0007" that would put you at 15 idle HOT. hopefully they didn't leave off a mains drill plug
smile.gif
we used to put piddler holes in them near the timing system for some gear drives on some V8.

Does this motor have HLA or SUB valvetrain?
 
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