Gents,

I was reading and I came to an old TSB, of 2012 in here : https://forums.mbclub.co.uk/threads/...filter.226923/

I am attaching the screen capture because there is a typo I have corrected :




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What I want to emphasize is :
The TSB failed to mention the important fact about M276 oil cap.

This is M276 oil cap.



The important component is inside, the OIL BY-PASS valve.



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Note : As part of 10th years refresh on all plastic handling important fluid. I have installed a new oil cap on my engine.


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M272 oil cap, don't ask me where the oil bypass valve is...I don't know.



This is the best tear down I can get on the net, the M272 oil cap stand pipe. It does not look like oil bypass is there.





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Since M272 oil filter is part of the oil filter housing combo with engine oil cooler, I think the oil by pass valve is inside this combo assy. Those who knows M272 well, please chime in.
https://www.ebay.com/itm/126114777603


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I then look for videos on youtube, hoping to see if anyone made a mistake by using M272 oil filter on an M276 ?
I found one, but its kinda unique.

Video is set direct to 3:45 minutes

So whoever replaced the engine oil and its filter prior to this Mr Sergei video, did the screw up.
However the screw up is unique because how the hell did the guy managed to get a stand pipe of M272 oil filter , which is not sold separately. One must buy the oil filter cap of M272 and cannibalized the stand pipe.
I mean if one goes thru such trouble to procure or cannibalized a part not sold as stand alone, how did he missed the fact that M276 uses different oil filter to M272 ?






Since W212 is getting so cheap by now this age..... I am noticing so many new owners of pre-owned W212 this year alone.
I hope newbie owner of pre-owned W212 with M276 does not screw up their oil filter purchase because many videos lack of mention of engine model.
E350 W212 is what usually mentioned, but not the engine variant M272 or M276.9 .


Okey doky.... M276 newbie owners, don't screw up and buy genuine oil filter only because it is the fleece one, good high flow media.

 

You can push the oil by-pass valve to test its movement. It will sink-in aka open when pushed with your finger.
Can it break ? Sure, it is plastic 100%, except for the spring.






Here is a good video from Chrysler engine. MB and Chrysler was once "sex" partners

Good read : https://www.noln.net/home/article/11...ter-2016-08-01

Good video :



Here is another fun fact. BMW B58 engine oil filter. I really hate plastic !!!!!
Probably due to 2 years recommended oil filter replacement, the plastic internal to the oil filter simply gave up and the oil filter element plastic end cap broke and got stuck at engine side....LOL.
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https://bmautomotivesolutions.co.uk/...uring-removal/


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https://f30.bimmerpost.com/forums/sh....php?t=1624354





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Oil killing plastic is not new actually.....

 

Let's be clear. The M276 oil filter should look like this:

 

and here is the plastic bypass valve...

cost efficient solution


bypass valve itself

When that contraption quits... contaminents are free to plug the oil pump solenoid or shared squirter Cyl. 1+4/5: RIP.

Oil bypass is said to open on pressure differential during start-up and accelerations... how good is the mechanism to positively shut it ?


> Sudden death...
​​I see that BMW aftermarket suppliers upgraded all these cheap plastic parts with aluminum grade... bypass valve and filter cover.
They must had reason to be motivated

​​​​​​I think keeping oil temperature nicely regulated without artificially building extreme heat... can only help.

 

No idea, should be decent but I do not expect 100% leak free integrity. 99% maybe.
It is hard plastic of by-pass valve to kinda hard plastic of the filter element end cap, so it is not o-ring or flexible seal kind of "tight".
The oil filter housing cap is cheap, so every 10 years replace it.... is good enough preventive.

Initially I am more worried about the overall filter housing plastic body aging and cracking more than anything.
60 psi is what it is exposed too I am sure, at cold start and 55PSI when I rev pass 2,200 RPM.... that is a lot for something that big a diameter and at 95C or more temperature.

 

I don't understand how that stainless steel spring works to open on pressure difference...

the spring is pushing in the same direction as the incoming unfiltered oil pressure.

incoming pressure is not trying to overcome spring pressure

cleaner oil exits down the filter center.

The other thing is... there are absolutely NO SEAL on top or bottom of filter media between clean/dirty oil.

bottom mating surface


top mating surface

I don't think a clean filter has a significant pressure drop to force a lot of oil through unsealed surfaces.

 

My usual teslong boroscope is not with me at the moment and I do not have new oil filter element to play with.... but this is what I gather thru more inspection.

The big diameter plastic in cyan-green I call Ring 2 will move down together with the center sealing area Ring 1, which has a hole and I believe that is the oil hole.




Thanks to your oil filter element close up photo, the lip elevation ( gap ) is what separate the Ring 2 from the oil filter element plastic end cap and hence Ring 2 can then be pushed upward by differential oil pressure.
So the sealing is done by Ring 1 only.



Since the Ring 1 is like a mini stand pipe and is quite long, maybe 1.5 inch and I can't yet see its side view without my boroscope ,
for now I believe that mini hole within Ring 1 is the allowed opening size for oil flow when by-passed. So only the hole is oil path and not entire size of Ring 1.

Since the oil filter is a pressure fit into the oil filter ALU housing and oil filter plastic cap housing, the Ring 1 will never be out of oil filter element mid bore hole completely, otherwise the oil
filter element will then become loose fit.

The question comes to my mind now is, if the Ring 2 has that oil hole, there must be a way to shut it OFF when the bypass valve is not active.
Otherwise engine will always get some percentage of un-filtered engine oil.

There seems to be some more component in the middle of this oil bypass valve, assuming our M276 design is very similar to this one below you posted, we need to see close up what that is ?



I don't want to damage my retired oil filter cap just yet by removing its oil bypass valve, till I get a new engine oil filter and my boroscope to see its actual movement.
I will update.

 

Got my boroscope back.

I was wrong, the hole in Ring 2 is actually blocked, no flow.





The maximum movement of the bypass valve assy is only 5mm or 0.2 inch.



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So I guess this is the actual sealing region. See its concave/angled shape.



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I think the actual sealing region is very thin, in red. So move up a bit of Ring 2 at 5mm the oil flow will be plenty.


The bottom end stand pipe of the oil filter element itself is holding position when Ring 2 lifts up. So filter element will be firm sitting down and not loose shaky shaky.




The filter element bottom end sealing design is the same as top side. Thin sharp lip.



I guess that is how this oil bypass valve actually works........

 

This $50 filter housing is only as good as its inner bypass valve.


thin plastic under stress....
good until its last day, then dirty oil will bypass filtration

bypass has inner spring
The bypass valve has its own return spring


What are chances for survival of thin plastic under spring tension plus extreme heat ??
This filter housing is a smart maintenance item to replace.... I tighten mine by hand, not 25NM. The O-ring seal does not get torqued at all.

 

Get a new oil filter housing plastic cap per 10 years, life is then good
I agree, that by-pass valve is the weaker component most likely.

Plastics plastics.... I sure hate them when they handle crucial fluids at engine operating temperature.

 

Thank you for stressing the importance of this single point of failure. Oil carries the hotest fluid in the engine away from the valves and pistons.

Presumably the plastic bypass valve opens at each engine restart, couting down No of cycles left to dry out Cyl.1+4.

I will change this filter cover to genuine MB $50 (2x over priced) when I go to 0/5W-50 SP oil. High chances this is what jams pump solenoid + piston squirters.

 

SOLVED.

The oil by-pass valve is a 2 stage unit. The middle part is also a valve,,,dugggh.

Stage 1 the entire assy moves up or away from oil filter element.
Stagge 2 is when differential pressure is met, I think a tiny bit higher than stage 1..... it will lift up and open for more flow







Here is where i got it wrong.
The actual sealing area of filter element towards by-pass valve is marked in green below , the wide base plastic. I trace their mating region using silicone grease.


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So the entire Ring 1 is stationed inside the filter element end cap.






Filter element bore is 24mm and the Ring 1 bore is 22 at the top and 23mm at the bottom.
So average difference is 1.5mm worth of opening for oil flow , or approx 89 millimeter square of opening.



The biggest oil flow opening is surely the stage 2.
The spring being small seems firmer than the bigger spring, but it could be only because small spring is hard to hold/push for me.





4 holding claws for the oil by pass valve




Stage 2 as-is before removal.




If in a pure bad luck scenario, stage 2 spring broke free of its holder/piston ..... while the filter housing is lying somewhere not seen by techy. So piston stage 2 will fly out of filter housing...gone.
He may not notice stage 2 piston gone, it is too dark to see inside the filter housing.
The filter element insert friction feel and locking feel will be no change at all, because the actual work of locking is done by the green zone I marked below




END of report.....

 

So, our duty as owner now when doing DIY or getting workshop to do oil change is :

01. Confirm that the stage 2 oil by-pass piston is not missing.
02. Shake the oil filter housing for sound of loose debris...whatever broken parts.
03. Test big spring action of the oil by-pass valve by pushing the oil filter element in twice. It should move freely smooth by 5 mm.

 

Have you found any reported instances of this design oil filter housing failing on our engines?

 

Not yet and I doubt anyone will take notice of a missing stage 2 piston.
If the entire bypass oil valve broken off , maybe techy may or may not know.

The proper method is to first pushed in the oil filter element into the PLASTIC oil filter cap, it should click in and tight enough, sure we can spin the filter element ...its not that crazy tight.
The above method is what I am seeing in youtube.

If one does it the other way around : which is place oil filter element into the ALU filter housing on engine , and then place the PLASTIC oil filter cap, he/she would not even know
the oil filter element seat properly or not ....or that the oil bypass valve completely could be gone/broken.
This method I have not seen it yet on youtube, I hope no one is doing this method.

 

Thank you Master Surya for investigating this engine killer all the way through.

Thanks to your in-depth research, we don't have to be sorry unprotected fools !

This unassuming topic is outmost essential!
This plastic bypass will blow-up an engine before the oil pump has a remote chance to wear out cooling my engine....
Continants of concern are non-magnetic chunkies and shavings.





Filter bypass valve fully extended


bypass spring locking pins under stress


Complete bypass valve (courtesy MS!)


skinny plastic loaded by ~30psi spring tension...


bypass valve investigation


observe trapped contaminants ready to pass through... 😳


> Analysis of POTENTIAL FAILURES:
-- The valve construction acts as a cup, holding dirty oil contaminents, ready to enter oil galleries.

-- When the bypass opens during startup surge, stored junk gets pushed over to the clean oil side, ready to go find another spot to stop:

• piston squirters
• pump solenoid
• crank bearings

-- The plunger plastic construction is always under spring tension while normally closed. Who know for how long until it snaps....

-- Any sizeable material that's going to plug up oil galleries is going to limit oiling....


This is officially a plastic MAINTENANCE ITEM.
🤞

++++ CANCEL BYPASS OR WASH CONTAMINANTS ??

I still think there a good case for a "bypass cancel" like video above (bypass is for 10kMi calcium sludge ppl) - "SP" oils should prevent that!

OR

WASH filter CAP EACH OIL CHANGE IN KEROSENE/BRAKE CLEANER....


Thank you very kindly Master Surya!


I think we can issue a friendly warning for sludgy engines that can plug up filters.
When we switch oil for better grades, sludge gets mobilized into filter that gets increased drop pressure, that open dirty bypass - Welcome all the killer junk on the clean side!


> PRELIMINARY EVIDENCE 2nd Point of failure:
Observe the pressure ridges caused by the spring working soft plastic.


line not straight SHOWS PRESSURE STRESS!!


this piece takes the blunt of spring force... BENT UPWARDS ALREADY on-schedule 👍

The above pics show the spring stress in the plastic-toc tic-toc... That I believe is what blows up Cyl pair closest to oil pump, courtesy gold medal for research team Surya!

 

Yes, there is old dirty oil trapped a tiny bit on the bypass valve. No shiny metal glitter fortunately.

Next oil change maybe I will try to clean the oil bypass valve with brake clean....experiment sake.

The 2nd stage valve, its piston spring holder sure look scary. Plastic holding decently powerful spring.
Some of the damage must be from me trying to pry out the spring out of the piston, it was not easy space wise.



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The plastic piston stage 2 is under higher spring tension when this valve open up. The spring zero position pre-load is already quite high.
So cold country owners need to pay more attention as I believe the oil viscosity so thick at 32F or Zero Celcius, this valve will work OFTEN.




Imagine, at 32F / 0C the kinematic viscosity is 868 mm2/S, while me in the tropics at 30C/86F is only 143 mm2/S and at a mere 1,300 RPM oil pressure already hit 55-60 PSI cold start.
I think in 32F / 0C the 2nd stage oil bypass valve could open up more than 20 seconds.





The sludge of 39,000KM total and of like 11 oil changes from Day 1.