Bosch Combined Sensor Query

[kayzarh]

Hi,

I've swapped in a new engine on my Subaru and I have a Bosch combined sensor in stock oil pressure switch location. 

I am trying to prime the engine with oil (crank sensor disconnected) 

The voltage input will not move from 0.5V no matter how much I crank and my ic7 shows 0.00 bar oil pressure

When I disconnect the sensor the reading dropped from 0.5v to 0.0v(on pressure sensor pin) and the oil temp dropped to -40. 

Has the sensor failed? Have I developed a wiring issue or is there no oil pressure detected?

Thanks

[Adamw]

If its showing 0.5V wiith no pressure that would suggest the sensor is working and the wiring is correct.  Failed pressure sensors usually either short the 5V rail so all sensors start reading wrong, or the output will be intermittent/noisy, not just flat at 0.5V.  So I would be suspicious there actually is no oil pressure.  Perhaps the oil system was not primed correctly.

 

[David Ferguson]

Have you removed the spark plugs so the engine can turn over faster?  That often helps getting that initial oil pressure following a rebuild.

[koracing]

Test sensor by applying compressed air to it if possible, or double check with a mechanical gauge if feasible. 

If the engine was not primed with oil before installation it can take several minutes of cranking to build oil pressure as @David Ferguson says with the spark plugs all removed.  Alternatively, reverse prime the oil from the sensor location via a drill pump or similar device.  Personally I made up a rig using an oem oil pump for a 5SFE mounted to an aluminum plate I can spin with a drill and suck from a fresh quart oil container and into a spin on adapter in place of the oil filter.

https://www.instagram.com/p/CtzLTTExtkk/?img_index=1

[kayzarh]

Spoke to engine builder who said there is plenty of lube and can fire the engine up straight away (making sure oil filter fully saturated) 

Once engine started got healthy oil pressure.

So yeh sensor and wiring all good, issue resolved.