Oil pressure question

[KillerBMotorsport]

Originally Posted by Jefe159

I've always heard that most of the track guys prefer to NOT mount senders directly to the block due to the vibrations, especially at track engine speed. Perhaps both have some logic to them.

That's how they are intended to be mounted. If they weren't, you have remote manifolds for sensors to keep them all out of the way. Maybe my experiences are unique, but in my 30+ years involved with cars, the only sensors I've ever seen mechanically fail have been due to being smacked or wacked with something. Never once in-use.

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[moby4dick]

Cold start ~100 psi
Running ~60 psi
Idle ~20 psi

EJ257 block with sensor in the upper galley plug. So 8 psi seems really low. From feedback here I’ve read Prosport gauges aren’t that accurate though. That you can build pressure though is a good sign.

Originally Posted by truck7575

So i installed an oil pressure sensor and gauge on my 08 sti.. The oil pressure at idle is reading 8psi.. It does come up to around 50-60psi with rpms.. The sensor and sending unit are in the intake valley back towards the left center of the engine... This number seems low to me... What about you all? What should it read and does rhe sensor location make a difference on what the reading will be?

Thanks
Rick

[truck7575]

Ok so have my intake off.. I had to take it off for another reason.. And it looks like there is already a pressure sensor there.. Is that the same location that i need to move my sensor too? Is that an oem or aftermarket sensor?

[KillerBMotorsport]

Yes that's the OEM sensor (idiot light). Pull that out and put your sender in there

[truck7575]

Will that give me a cel or should i move it to the back port

[KillerBMotorsport]

Originally Posted by truck7575

Will that give me a cel or should i move it to the back port

No. It's a normally open switch, so removing it will not cause it to light up and it's not linked to the ECU at all.

You're far better off putting a real gauge/sender in there. The OEM oil pressure sensor turns on the idiot light when pressure drops below 2.1psi. It's more like a 'your engine just blew up' light.

[truck7575]

Great information thanks again

[truck7575]

The sensor will fit under the alternator easily if the intake manifold is off.. If your trying to install with the intake manifold on then you're best taking off the alternator.

[ThakurA]

Originally Posted by Haevn

I have a Prosport sensor and I’m using the plug where the factory sensor as and when my oil is hot in the 210-220 my oil pressure is around 15-20 at idle

I have a prosport oil pressure gauge also. But my hot idle reads 14-15psi. Not sure if its acceptable or low?

[benflynn]

Originally Posted by ThakurA

I have a prosport oil pressure gauge also. But my hot idle reads 14-15psi. Not sure if its acceptable or low?

What oil? I’d be looking for 30 min but I would wonder about accuracy of gauge

[blurred]

2 things

- use a y-fitting and keep your oem pressure sensor (when your aftermarket one is having issues or you're not trusting it, it's good to have a failsafe)
- lower oil pressure readings at idle are "normal" as sensors age when used in that location. And especially if using a sensor relocation kit, so 14psi could really be 30. If you're unsure to trust it change your sender, and while you're doing that hook up a mechanical gauge to test, if it's still low then you can worry a little

[Charlie-III]

Originally Posted by blurred

2 things

- use a y-fitting and keep your oem pressure sensor (when your aftermarket one is having issues or you're not trusting it, it's good to have a failsafe)
- lower oil pressure readings at idle are "normal" as sensors age when used in that location. And especially if using a sensor relocation kit, so 14psi could really be 30. If you're unsure to trust it change your sender, and while you're doing that hook up a mechanical gauge to test, if it's still low then you can worry a little

Pressure varies with oil temp. As the oil gets hotter, viscosity goes down and it "leaks" past bearings easier thus lower pressure.
Engine RPM has an effect, low RPM, low pressure. Higher RPM is higher pressure. Starting weight of oil makes a difference as well.
Pressure is highest by the pump, near the end of the oil gallery run, the lower the pressure since it's been leaking past earlier bearings.

A relocation kit that taps off right by the OEM sender should show an equal pressure due to the "incompressibility of fluids", no loss of pressure.

[ThakurA]

Originally Posted by benflynn

What oil? I’d be looking for 30 min but I would wonder about accuracy of gauge

Im running castrol 15w40 mineral oil for now. Once break-in mileage is done , will switch to 10w40 synthetic. Gauge accuracy im also doubting, will get a mechanical gauge and check for any variation

[blurred]

Originally Posted by Charlie-III

Pressure varies with oil temp. As the oil gets hotter, viscosity goes down and it "leaks" past bearings easier thus lower pressure.
Engine RPM has an effect, low RPM, low pressure. Higher RPM is higher pressure. Starting weight of oil makes a difference as well.
Pressure is highest by the pump, near the end of the oil gallery run, the lower the pressure since it's been leaking past earlier bearings.

A relocation kit that taps off right by the OEM sender should show an equal pressure due to the "incompressibility of fluids", no loss of pressure.

My post is based on my experience.

Oil pressure gauge with a big sender that required a relocation. At first was trustworthy, showed 25-30psi at warm idle on my chosed oil. After a year or two the hot idle numbers started dropping until they were 5-10psi (same chosen oil). I put in a new sender and instantly back to 25-30psi. Then after another year hot idle pressure was back to 0-5psi range. I changed to a greddy gauge with a nice small sender that fit my Y without relocation and for many years it remained solid at 25-30psi hot idle.

It was only hot idle pressures reading lower than actual with the relocation kit as the sender aged. High rpm and cold idle were accurate. So, my theory is that a dead-end relocation kit can decay those idle values over time and perhaps can't be trusted.

As for using a Y and the OEM sensor that kept my sanity when my gauge read 0.