S-Prihadi

Dang, 2 months special order.
I am the only dude who actually buy such thing from MB Indonesia.

I bought the one for my own engine.


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CORRECTION : The valve #1 travel is 4.x mm not 14mm, sorry.

The guesstimate INTERNAL construction of the piston oil jet is below, based on me poking around the valve item #1. Sorry me can't draw any nicer.
Observe the #4 BLEED HOLE



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Yes, there is a BLEED HOLE , item 2 for below.





BMW's oil jet has valve too but no BLEED HOLE




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Other MB engine's piston oil jet, all of them have bleed hole

M276.9 3.5 NA





M278 and surely M272 / M273 the same, because the P/N belongs to M272






Why the hell M157 uses M278 P/N while M278 uses M272 P/N ?
For M157 P/N is A2781800143 Oil spray nozzle, piston cooling




M156
For M156, P/N is A1561800543 Oil Nozzle, piston cooling





WILL CONTINUE...............

S-Prihadi

Please be aware, at this point in time, the test is still using air ( nitrogen) and not liquid water or oil....yet.
Me gotta buy or make oil vessel capable of sustaining at least 65 PSI. So be patient.

The density of air is so much lighter than oil, so the result for air is most likely not very accurate for certain behavior of the bleed hole vs the goose neck in its oil output.





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The pressure reading is using my HVAC wireless pressure sensor. In PSI.



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The re-seating ( closing ) pressure of the valve inside is 24.5 psi, after being opened at 31.x PSI.


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CORRECTION : The valve #1 travel is 4.x mm not 14mm, sorry.
Now look again at the oil jet internals.



At 31.x PSI, the valve #1 starts to lift up enough to allow air to flow in good volume..... HOWEVER, the bleed hole is the one getting the most air output and not the goose neck.



Only at 35 PSI, then the valve #1 moves up enough and starts closing the bleed hole #4.
Total travel distance of valve #1 is 4mm,

I think MB uses such design is to achieve proper or maximum oil spray opening to the goose neck when oil pressure is probably near 40 PSI.
The higher the pressure is, the more valve #1 moves up and starts to restrict bleed hole #4.
It will not shut totally #4 bleed hole, but perhaps 90% closed/choked.

Seeing the oil pressure curve for defeated oil pump solenoid.... for my engine :



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I would think 1,750 RPM would be the good volume and distance oil spray , being at 41 PSI.


I am a bit confused on why MB chose a design with bleed hole ?? There must be other technical reason behind it.


I hope in a week, I can have the proper oil vessel/container to do the test with engine oil....or maybe cooking oil

CaliBenzDriver

That's a lot of great information for our piston squirter that opens at about 30psi. It's got some smart engineering built into it. It's more than ball-on-spring valve.

We know the oil pump produces volume... what happens to pressure when all squirters open?

When available volume can not supply ALL squirters at once, the pressure drops back lower.


If we test system with high volume at regulated pressure is this indicative of squirters under our limited pump volume??
-- We have very limited volume at lower RPM.
-- Pressure drops when flow volume is not replaced.
-- Pump has to deliver enough volume for ALL squirters + bearings to hold pressure....
-- Squirters has a specification for "flow volume per psi" that pump must meet.

The bleed hole may help the valve open up with absolutely no back pressure.... (**): drains while unused.

I wonder what happens to pressure when the bleed port is not fully shut during squirter opening? (bleed port may be fully shut with minimal movement).


When a dual-squirter fails... so does the cylinder pair it is serving.

(**) Squirter's bleed port:
a way to prevent solid deposits from accumulating when heatsoak cools down. Oil drains out leaving clean pipes.


a proven way of stabilizing operations

The delta between opening and closing is called hysteresis. It's used to prevent valve hunting during operations.
When pressure drops during opening at 30psi, the valve does not close until 25psi is reached, likely does not happen because of hysteresis. It would close with 30/30, so we have 30/25.

S-Prihadi

To answer your questions, we need to ask her.....