Oil pump question for the mechanics

[Lucero]

just kind of an off-shoot on the chance that a mechanic dropped their tools to frequent this sub.

my oil pump has some issues:



this portion is a bit worn but since I'm rebuilding the engine I wanted to know if this is worth buying the entire housing or if it can be fixed.

[Tcoat]

If you have any doubt buy a new one. Don’t go to all that trouble and expense just to cheap out on the very heart of the engine.

[DarkPira7e]

In addition to what Tcoat said, people have a hard time getting that oil pump to seal properly after removing it from its chamber in the front cover. I would just get a new front cover, it comes with everything you need ( and won't be potentially gouged from being removed)

[KillerBMotorsport]

That pic is small, and you've not described what's worn out, so there's no way to know. Like Tcoat said, if it's questionable, don't risk it.

If there's a lot of miles, It's a good idea to replace it.

If the engine experiences a catastrophic failure, it's a good idea to replace it.

If it has low mileage and you want to save some money, and have some precision measuring tools, you can check the pumps dimensions to see if you're within service or at wear limits.

If you do buy a new pump, it's recommended to disassembly and check the bypass plunger for smooth action. The backplate screws should also have Loctite applied.

[Lucero]

Originally Posted by KillerBMotorsport

That pic is small, and you've not described what's worn out, so there's no way to know. Like Tcoat said, if it's questionable, don't risk it.

If there's a lot of miles, It's a good idea to replace it.

If the engine experiences a catastrophic failure, it's a good idea to replace it.

If it has low mileage and you want to save some money, and have some precision measuring tools, you can check the pumps dimensions to see if you're within service or at wear limits.

If you do buy a new pump, it's recommended to disassembly and check the bypass plunger for smooth action. The backplate screws should also have Loctite applied.

Thanks for the input, The car does have a of of miles 135k+; there is no way to replace that specific portion without buying the entire oil pump assembly which includes the housing so it comes down to having to spend $450+ for something that may or may not make a load of difference. The 'damage' though i'm not sure if it's standard wear, comes from the oil drive gear leaving marks on the oil gallery assembly, specially the pictured casting plate.

Thats being said, if the expense is going to happen then would there be a good after market option with better distribution/performance?

[Grady]

Originally Posted by Lucero

miles 135k+

I would replace it.

[Ultramaroon]

Wear limits and inspection procedure are not in the manual. That's a first for me.

[KillerBMotorsport]

Originally Posted by Ultramaroon

Wear limits and inspection procedure are not in the manual. That's a first for me.

Factory Service Manual

[KillerBMotorsport]

Originally Posted by Lucero

Thats being said, if the expense is going to happen then would there be a good after market option with better distribution/performance?

The factory suby pumps have excess flow as-is. The best thing you can do is disassemble, check the bypass piston for smooth action, and reassemble with Loctite on the backplate bolts.

[Ultramaroon]

Originally Posted by KillerBMotorsport

Factory Service Manual

Look in my sig line

[KillerBMotorsport]

Originally Posted by Ultramaroon

Wear limits and inspection procedure are not in the manual. That's a first for me.

At home, but this is what I have handy. It's for an EJ but makes the point. Are the manuals you have links to actual FACTORY Service Manuals, or made by a third parts? What we use is created by Subaru.

FWIW, same type of pump is used on both engines.

[Ultramaroon]

Originally Posted by KillerBMotorsport

At home, but this is what I have handy. It's for an EJ but makes the point. Are the manuals you have links to actual FACTORY Service Manuals, or made by a third parts? What we use is created by Subaru.

Let me know what you think after reviewing. I understand that they were ripped directly from TIS but your chart is what I'm used to seeing. I have a whole bookshelf full of FSMs for cars I and my family have owned. I'd gladly pay for hard copies of everything available for the twin too.

[fableluke]

Originally Posted by KillerBMotorsport

The factory suby pumps have excess flow as-is. The best thing you can do is disassemble, check the bypass piston for smooth action, and reassemble with Loctite on the backplate bolts.

Been having oil pressure that seems low. ~5psi at idle around 176F. My thought was bypass piston is stuck open or isnt working correctly. Opened up the oil pump assembly to see some scoring in the oil pump gears. Not sure how to check bypass piston but i disassembled it. The plunger/piston took some help to get out but it somewhat moves smooth. I already have a new front timing cover but i was hoping to find something that would explain my low oil pressure. You know what could low oil pressure? Ive already pulled the pan off to look at the pickup tube and couldnt find anything.

Thank you!

[KillerBMotorsport]

What is the mileage on that pump assembly? Looks to be some decent scoring. How do the rotor faces (teeth) look?

The bypass should move smoothly. Not somewhat smoothly, it should be smooth. It should also come right out. Is the plunger bore scored? Plunger itself have any wear?

Not uncommon, if a plunger sticks, it happens when cold and pressure is highest. as the oil warms, the plunger stays open and pressure will tank. 5psi at idle is LOW. What location were you measuring pressure at?

I would cut apart the oil filter just as a precaution in case there is more going on here.