Piston Cooling Oil Spray Nozzle opening pressure




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...............
Last edited by S-Prihadi; Jun 30, 2024 at 11:07 AM. Reason: add info




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

Last edited by S-Prihadi; Jun 30, 2024 at 11:13 AM.




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.
Last edited by CaliBenzDriver; Jun 30, 2024 at 12:38 PM.





We do not have full control nor all the answers. Live testing can help us achieve results under real conditions regardless of unknowns.

In a perfect world we would calculate an RPM for effective cooling. I could not do that.
Instead I tested oil viscosity (ie. volume/pressure) vs. smoke point RPM.
I realized I could prevent vaporizing burnt oil with a bit higher viscosity within the W40 range.
Removing heat from pistons with tiny squirters stream is a slow process that must stay ahead of producing heat.
The only control we have is RPM + viscosity.
But when you only raise RPM on thin oil, the outcome is more heat... NOT MORE COOLING !

The key is removing more heat than engine is producing at any driving RPM.
Limiting cooling to randomly or above 3500.RPM stores extreme heat for extreme heatsoaks stressing coolant relief through leaks.
Whatever psi is necessary to stop burning oil, the effective number is tied to effective viscosity at unknown temp near 200F coolant.
The effective cooling RPM rises up when viscosity is lost due to heat stress. To counter that prevent extreme heat.

In another thread I said that pistons cooling requires a fire-hose output, not a garden-hose stream at 32PSI.
Here we have tiny flow pipe and want the moon... The only way I found to provide an effective cooling flow is with pressure ie. viscosity.
Last edited by CaliBenzDriver; Jun 30, 2024 at 02:46 PM.
Last edited by Rickman30; Jun 30, 2024 at 02:57 PM.
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Interesting because I assumed the oil valve opened the circuit to those. This setup is better. Nice, thanks for the details and pix
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I'd still want an external oil cooler. and a lower coolant thermostat, say 190 degrees F without computer controls.




shopping outlet crawl
...sorry the wife keeps tugging on my sleeve. Drove inland to get 100°F weather

Last edited by CaliBenzDriver; Jun 30, 2024 at 07:20 PM.




I been watching Lake Speed Jr in his few channels and one more in Lubrication Explained ( LE ).
https://www.youtube.com/@LubricationExplained
I been watching Lake Speed Jr in his few channels and one more in Lubrication Explained ( LE ).
https://www.youtube.com/@LubricationExplained
My wife even enjoys the Lake Speed Jr. stuff too. She was working in the automotive industry when we met. Very knowledgeable, makes having automotive mechanical conversations at home much more enjoyable. Boy she has some stories from the retail side what some customers have and will do to their cars.




Me wife is a diver too like me, so we used to be dive buddy.... we talk about good eating fish often heheheh.
There is one more channel I really enjoy, husband and wife team both Germans, but Range Rover cars. LR Time.
They are so fun to watch and hubby is VERY VERY knowledgeable. They are funny and smart.
A lot to learn from them too from Range Rover perspective: https://www.youtube.com/@Vera_and_Christian
This is the only non Mercedes channel or non workshop like Pine Hollow, which I actually subscribed to.
I don't usually subscribe to personal car DIY channel, but LR Time is a class in its own when you watch them enough.
Me wife is a diver too like me, so we used to be dive buddy.... we talk about good eating fish often heheheh.
There is one more channel I really enjoy, husband and wife team both Germans, but Range Rover cars. LR Time.
They are so fun to watch and hubby is VERY VERY knowledgeable. They are funny and smart.
A lot to learn from them too from Range Rover perspective: https://www.youtube.com/@Vera_and_Christian
This is the only non Mercedes channel or non workshop like Pine Hollow, which I actually subscribed to.
I don't usually subscribe to personal car DIY channel, but LR Time is a class in its own when you watch them enough.





D-Tech is also good, if you have not watch him. BMW is his expertise, but he got some MB too. https://www.youtube.com/@DTEAuto
There is one guy and his work on oscilloscope is good to watch, too bad he more to Nissan. https://www.youtube.com/@CartersDiagnostics
I have to finish watching later.




Ivan troubleshot all the way to a distressed female connector pin as the source.
Very well done!!
Yes, it is bad but not "factory bad" like our "solderless pins"...
Whomever worked on this last damaged that pin while probing it.
Ivan reconnects ALT LIN then returns the car as fixed.
I think this is dealing with what MS! and myself call the "voltage Yo-Yo".
This is an amazin Bosch system bug that drains battery and soft-crashes electronics.
The real issue is that the system comes preloaded with untested design bugs no one cares to address with a working fix.
I the case of MB battery drain it is caused by poor networking between modules.
Not ECU,
Not BATT
Not F_SAM
Not R_SAM
Not ALT
All the disposable solderless modules with ESP has chief purveyor of referred chaos though CGW network bridge.
Fixing this requires to undo all the setup put in place to down grade basic reliability.
This bug highlights the lack of network supervision tools. The lavk of visibility is going to keep plaguing users.
Last edited by CaliBenzDriver; Jul 4, 2024 at 05:01 AM.
Ivan troubleshot all the way to a distressed female connector pin as the source.
Very well done!!
Yes, it is bad but not "factory bad" like our "solderless pins"...
Whomever worked on this last damaged that pin while probing it.
Ivan reconnects ALT LIN then returns the car as fixed.
I think this is dealing with what MS! and myself call the "voltage Yo-Yo".
This is an amazin Bosch system bug that drains battery and soft-crashes electronics.
The real issue is that the system comes preloaded with untested design bugs no one cares to address with a working fix.
I the case of MB battery drain it is caused by poor networking between modules.
Not ECU,
Not BATT
Not F_SAM
Not R_SAM
Not ALT
All the disposable solderless modules with ESP has chief purveyor of referred chaos though CGW network bridge.
Fixing this requires to undo all the setup put in place to down grade basic reliability.
This bug highlights the lack of network supervision tools. The lavk of visibility is going to keep plaguing users.
It’s why the method of adding products like Stabilant 22 to connections, it creates a molecular type bond in the connection, be it positive or ground, the result is stability in the current load, and reduces the voltage drop. Leaving only the yo yo to correct.
I think I have a dying diode in my alternator. Interior lights flicker looks like around 30 cycles or less. I scoped the ripple but it looked good. I’m going to scope again, first ensure the lamps are flickering then look at the ripple without the extended test leads. One of the cool features of the Snap-on tools, you can create a test and save it to preset tests.
You are also correct, most shops and owners just fire the parts cannon, instead of trying to fix, no parts required. Once I find the offending diode, I’ll do just like any big name remanufacture does everyday, replace just the broken part and clean it up and send it.




Using Mobil 1 0W30. Ambient and thus oil temperature 30C.
Test set up :
Nitrogen tank, pumping nitrogen to the inverted filter housing.
Nitrogen pressure reading is right after the nitrogen regulator.
From nitrogen regulator 1.5 meter 1/4" refrigerant HVAC hose to filter housing INPUT.
From filter housing OUTPUT, another 1.5 meter 1/4" HVAC refrigerant hose and then to short clear hose and to the oil jet nozzle,
Total head resistance is 1.5 meters of small 1/4" hose filled with nitrogen and 1.5 meters filled with engine oil + whatever resistance to flow the filter housing has.
The nitrogen regulator airflow is not able to catch up with the oil output, so nitrogen pressure drop a little as oil started flowing out of filter housing,
and increasing the air space volume in the oil filter housing.
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The test in video :
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Summary........
Once air pressure ( oil pressure ) hit above 41 PSI the valve in the oil nozzle opens up really good and the bleed valve is leaking only so very little oil, which we can say it is zero leak.
39 PSI is the closing of the oil nozzle valve.
Note : I can't read oil pressure actual pressure at filter housing output , I can only read the nitrogen pressure pumping the filter housing.
Let's assume it is the same.
So it is safe to say that 41 PSI the oil spray distance is good enough at piston BDC and if 45 PSI or more, oil spray distance is good to TDC.
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No worries my friend. Been there...