For some reason my oil pressure at idle reads 25psi. Cruise it reads 50psi. The engine rebuild shop told me that it was supposed to be a 85psi regulator.

Now for some reason I cannot remember what pressure it was until my friend pointed out it only read 25psi. I thought it read 50psi+ at idle before or something.


What could create a pressure loss?

Thanks,

(I'm not low on oil either)

 

You may have a bad O-ring on the front cover. that's the only oil passage I could think of that could potentially cause the oil pressure to drop.

 

and that o-ring can cause some serious bearing damage very quickly. I've had one slip and clog the passage.

 

how much pressure should 13b's with the FD OPR/bearings idle/WOT with when warm?

 

Really?

Would I not see some sort of oil collecting somewhere? What would case this to change all of a sudden?

Not sure if you remember but you tuned my car. 410rwhp @15psi.

Thanks for the input.

 

I don't see anything wrong with your idle oil pressure.
Check to make sure the oil pressure goes over 70psi at 4kRPM or so...unless you're running really thin oil?

I think the Mazda spec for oil pressure at idle is about 15 to 30psi?
So that's in spec.

The RB "street" OPR only bumps up the pressure about 10% or so...


-Ted

 

25psi is way more than enough at idle. The people who like to brag about being able to peg their oil pressure gauges at idle are merely overworking their oil pumps and wasting power.

 

I have the same 85 psi regulator that Ian is supposed to have. I generally see 50-60+ psi at idle and 80+ psi at around 3000 rpm. 20W50 oil.

I guess comparing it to my numbers has him worried.

-eViLRotor

 

The regulator doesn't come into play at low engine speeds where the pump isn't flowing enough volume to build enough pressure to blow the regulator off.

It does depend on a lot of factors, like the viscosity of the oil, oil temperature, bearing clearances, and oil pump size. OTOH, I see more a difference between new oil and used oil (10-20psi at cruise RPM) as compared to the difference I see between 20W50 and 5W20. Then again, that's comparing old 20W50 and new 5W20...

 

What is ambient?
Are those numbers for a totally warmed up engine?

Stock or aftermarket gauge?

If it's stock, the sensor is bad.

If aftermarket, something is wrong.

I run the same RB 85psi OPR.
I see 15psi at idle.
I run 15W40 Shell Rotella-T oil.


-Ted

 

I checked it today. Fully warmed up car.
Ambient temp was about 30C (86F). 45 psi at 1000 rpm idle, autometer ultra-lite gauge.

 

Oh, another question is the oil pump cavity been ported?
This seems to bump the idle up at least another 5psi to 10psi.
My engine doesn't have this mod...yet.



-Ted

 

Hey Ted, I have the oil passages ported and I have a bellmouthed oil inlet with no bugscreen and I still have 15-20psi hot idle, and 45psi hot cruise.

 

I race a 13b in SCCA Nationals, have an external, adjustable oil pressure regulator, and only run 60 psi at 8k rpm. Not giving advice, just saying what I do.

 

Mine is 20@idle warm, and ~70-80@WOT, those are the only two throttle positions my car sees

 

hey ted, just wondering, why are you running that diesel oil? trying to keep the carbon down or what?

 

mine is ~25 at idle and ~65 above 4k.

 

Just an experiment...
Wanted to try something different...



-Ted

 

i did it for an oil change one time... did seem to clean up some carbon...or at least judging by how nasty it was when it came back out