PSA: Oil Pressure, Pre-filling oil filter, and priming oil system

[SageAbkatsor]

I just wanted to share my experience with engine priming last night.

 

I was following IAG’s engine priming and break in instructions. It says to pre-fill oil filter, disconnect crank position sensor, and then crank the engine in 15-20 second intervals until the oil pressure light goes off.

 

We followed these instructions but after maybe 5-10 15 second cranks, the oil pressure light would still not go off.

 

Looked everything over and nothing is leaking, my builder is confident in everything he has done, so what gives?

 

I was fortunate enough to find this video:

 

The issue was that we pre filled the oil filter. The air bubble between the oil in the sump/pump and the oil in the filter is able to pressurize but not enough to force the oil in the filter out.

 

We did as this video instructed and pulled the filter, nervously cranked until oil came out. Reattached the filter, still pre-filled, and then proceeded to prime it again.

 

Within about 2 or 3 15 second cranks the light went out.

 

I am now slightly nervous about the amount of cranking that was done, but my builder told me not to worry about it. It wasn’t a lot of cranking, and that is what assembly lube is for. Plus IAG builds quality stuff. Still, was a little bit of a nail biter for a second there.

 

Again, just figured I would share my experience.

 

TLDR; if you pre-fill your oil filter, it may prevent you from properly priming your engines oil system.

[DaveWaters]

This happened to me too.. Got sick to my stomach that I somehow did something wrong on assembly. Glad I walked away and googled. I found a thread on nasioc that lead me to pulling the filter as well. Once I put the filter back, within seconds I had pressure. Holy crap that was scary. My buddy said I was white as a ghost. Now we laugh about it.

[Enlight]

Flatirons Tuning is putting out some of the highest quality Subaru specific informational videos right now. That video helped me too after my car sat for a year and I swapped out the oil pan.

[awfulwaffle]

I almost pulled my pump to prime it and reinstall before I found that video.

[RustyRuu]

that is an interesting encounter, something that may ease your mind on over cranking an engine with no oil pressure while you try and trouble shoot, is this sweet tool.

 

https://legacygt.com/forums/showthread.php/diy-oil-system-priming-tank-214760.html

 

wont help with that air bubble i don't think but will get oil to your bearings while you try and figure stuff out, and just great to do on a fresh build anyway.

[Max Capacity]

Just saying, after 130,000 miles on the ej257, which has no bearing of rod or piston noise, I just started it like I do everyday. I had the fuel system primed a couple of times while checking other stuff.

 

When it came time I turned the key to start, 2 or 3 cranks later, the engine was running. Oil pressure light went out, like it does everyday.

 

You get a lot more oil pressure at idle then you do at cranking rpm.

 

I remember cranking the race engine in the Civic waiting for the direct reading oil pressure gauge to show pressure, it took about 40+ seconds, felt like forever.