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I would not disconnect power to Y130 of an M256, I think it is not suitable because its split-oiling design is not the same as M276/M278/M157 2 stage oil pressure technique.
It wrote : The goal then is to supply the hydraulic camshaft positioner with the required level
of oil pressure, so that an adjustment at the required speed is already possible at idle speed.
This explanation seems to indicate that MB realized the VVT-cam phaser found on our M276/M278/M157 owners would do well with higher oil pressure at idle.
But M256 has another oiling requirement for camshaft region , its CAMTRONIC variable valve lift capabiity, while the actuation is using electro-mechanical solenoid,
the actual work is pushing camshaft to change its lift is mechanical/friction.
Now we do not know the oiling capacity of M256 oil pump and what pressure at idle is it getting with split oiling....while at reduced oiling aka idle or whatever RPM used to trigger maximum
oil pressure + flow.
But I read its basic oiling spec as good news, this part : The goal then is to supply the hydraulic camshaft positioner with the required level
of oil pressure, so that an adjustment at the required speed is already possible at idle speed.
If there is an oil pressure test port like M276 engine , in ur M256, I suggest do more homework on its actual oil pressure idle to WOT .
Don't go in blind, M256 is not M276/M278/M157 in its oiling design.
Good luck...
Last edited by S-Prihadi; Feb 21, 2025 at 05:05 AM.
Based on Master Surya's research it seems Mercedes-Bosch further reshuffled the cards.
In M256 MB uses "multiple oil pressures".
The VVT can get full pressure while
The pistons get low pressure....
That means room for reliability improvements.
> What To Do...:
You'll want to select the targets you want to experiment with.
It may well be you only need better viscosity to help spray pistons heat away.
That in itself is a tall order because oiling helps timings that help heat meaning its not only the oil that directly drops heat after the 1st Mile. It's the ECU adapting its maps over x-many miles.
There's a chance the M256bcamshaft positioning is now reliable ONCE PROVIDED WITH PROPER PRESSURE.
Meaning do not expect VVT effectiveness on MB stock 10kMi thin oil.
You want to pionner effective VVT pressure & piston spray. We'll help ya read your tea leaves.
From WIS perspective MB still minimizes everything to save gasoline fumes.
++++ TRANSLATION...
the way I understand M256 setup is a conventional single pressure pump supplying VVT and using a solenoid to limit piston sprayers.
Note that when you enable the piston sprayers you NEED ENOUGH PUMP VOLUME/PRESSURE AVAILABLE not to starve existings.
Again that sounds like better viscosity is gonna be your ticket.
Meaning you don't want to starve engine head(s) to spray pistons on thin oil at 1500.Rpm: can't do!!
Practically assess stock engine issues...
-- Engine poor throttle control ??
-- Gearbox sloppy shifts ??
-- Extreme heatsoaks ??
-- New issue ...
Based on your inputs we can help.
Last edited by CaliBenzDriver; Feb 21, 2025 at 09:12 AM.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by exturnul
from almost everything i'm reading - the turbo heat soaking while idle could be related to a whole host of failures ...
Where are you reading that? Idling actually allows the turbo to cool down, not heat up. That's why a lot of people in the VW/Audi world (and probably others) add turbo timers to allow turbos to cool down after hard runs. Many manufacturers have auxillary coolant pumps to keep coolant circulating through the turbo after shut-down.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Hmmmm, it seems like Mercedes has attempted to "fix" the 2-stage oil pump problem with the new M256 engine.
To Cali's point, we don't know enough yet to understand how modifying (i.e., disabling) the oil pressure controls will affect this engine. I would be inclined to leave things alone mechanically until more is understood. And if the factory fill in the engine is 0W-40, I would only go to 5W-40 for now (unless the Operator's Manual states 5W-50 is OK).
Where are you reading that? Idling actually allows the turbo to cool down, not heat up. That's why a lot of people in the VW/Audi world (and probably others) add turbo timers to allow turbos to cool down after hard runs. Many manufacturers have auxillary coolant pumps to keep coolant circulating through the turbo after shut-down.
See, my 3000GT's has turbo timers so the 9B's could ponder their poor performance as a punishment for not moving the boat faster than a 13.6 (stock). With my AMG, if the car is idling the turbos get red hot mad because they want to be performing. It is like benching the captain of the team not not expecting his blood pressure to rise (if he is a he, as many team captains are he's, but for the she's that are he's....)
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by OldManAndHisCar
See, my 3000GT's has turbo timers so the 9B's could ponder their poor performance as a punishment for not moving the boat faster than a 13.6 (stock). With my AMG, if the car is idling the turbos get red hot mad because they want to be performing. It is like benching the captain of the team not not expecting his blood pressure to rise (if he is a he, as many team captains are he's, but for the she's that are he's....)
🤯 OK, you're starting to sound like another of our favorite contributors...
Based on Master Surya's research it seems Mercedes-Bosch further reshuffled the cards.
In M256 MB uses "multiple oil pressures".
The VVT can get full pressure while
The pistons get low pressure....
That means room for reliability improvements.
> What To Do...:
You'll want to select the targets you want to experiment with.
It may well be you only need better viscosity to help spray pistons heat away.
That in itself is a tall order because oiling helps timings that help heat meaning its not only the oil that directly drops heat after the 1st Mile. It's the ECU adapting its maps over x-many miles.
There's a chance the M256bcamshaft positioning is now reliable ONCE PROVIDED WITH PROPER PRESSURE.
Meaning do not expect VVT effectiveness on MB stock 10kMi thin oil.
You want to pionner effective VVT pressure & piston spray. We'll help ya read your tea leaves.
From WIS perspective MB still minimizes everything to save gasoline fumes.
++++ TRANSLATION...
the way I understand M256 setup is a conventional single pressure pump supplying VVT and using a solenoid to limit piston sprayers.
Note that when you enable the piston sprayers you NEED ENOUGH PUMP VOLUME/PRESSURE AVAILABLE not to starve existings.
Again that sounds like better viscosity is gonna be your ticket.
Meaning you don't want to starve engine head(s) to spray pistons on thin oil at 1500.Rpm: can't do!!
Practically assess stock engine issues...
-- Engine poor throttle control ??
-- Gearbox sloppy shifts ??
-- Extreme heatsoaks ??
-- New issue ...
Based on your inputs we can help.
Will get a gauge installed either today or on monday and we will start data measurements. I think I’m on 5w-30, I don’t know what the dealer put in for my first fill - gonna move to 5w-40 and see what my requirements are. It would make sense though since most of the M256 problems are related to electrical / overheating issues that were all coded out with software
Where are you reading that? Idling actually allows the turbo to cool down, not heat up. That's why a lot of people in the VW/Audi world (and probably others) add turbo timers to allow turbos to cool down after hard runs. Many manufacturers have auxillary coolant pumps to keep coolant circulating through the turbo after shut-down.
Not the actual engine internals - but the turbocharger reported by many forum users is failing prematurely and I would believe it’s due to insufficient oil circulation while idle, especially after hard use. It won’t heat up but it certainly won’t help to cool down
Plus the heat from said turbo at idle is causing engine harnesses to possibly melt and disintegrate
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by exturnul
Not the actual engine internals - but the turbocharger reported by many forum users is failing prematurely and I would believe it’s due to insufficient oil circulation while idle, especially after hard use. It won’t heat up but it certainly won’t help to cool down
Plus the heat from said turbo at idle is causing engine harnesses to possibly melt and disintegrate
I have NEVER seen that happen from simply idling (or any other condition). Any harnesses should be (and probably are) shielded from turbo heat. And, at idle, oil pressure is still sufficient to keep circulating through the turbos. They are also water cooled (primarily). Next time you come across someone claiming that their wiring harness or other parts were damaged by the turbo at idle, please post a link here.
At idle, the wastegate is open (by default), allowing most exhaust gases to bypass the turbine, so it is spinning minimally and not generating heat. Oil pressure is ~1 bar (15 psi) at 600 rpm.
My comments are based on stock turbos as from the factory. If someone has kludged up their settings with aftermarket "performance" components, then all bets are off.
Not the actual engine internals - but the turbocharger reported by many forum users is failing prematurely and I would believe it’s due to insufficient oil circulation while idle, especially after hard use. It won’t heat up but it certainly won’t help to cool down
Plus the heat from said turbo at idle is causing engine harnesses to possibly melt and disintegrate
That's one nail in the coffin for M256 storing uncontrolled heat.
Why do they insist on storing extreme engine heat in dry pistons when all the evidence indicates poor reliability?
How are stuck rings supposed to be better ??
Now that's one thing you can focus on cancelling for greater results: "Normal Engine Heat" minus toasted oil-in-harness + ECU failures.
You can be the first one to enjoy M256 without the steaming heatsoaks... the key is to simply remove heat as its being produced at driving Rpm.
Storing heat in dry pistons leads to engine/tranny heat failures.
Find out what kind of stock oil is used then step up viscosity to lower spray Rpm... with trial and errors you'll be able to gain effective cooling and an effective protection film.
Are you going from 10w30 to 5w40 or from 5w40 to 10w50 ??
+++ One Thing To Another...
We dont particularly need melted harness, toasted CPS sensors or cracked coolant conduits... we need to recognize what uncontrolled heat does in the engine bay: oil viscosity is strongly tied to its temperature.
When temps swing up 50°C the ECU/TCU are out of control range. Poor VVT and noticeably weaker shifts (more bangy when cold!). HEAT NOTICEABLY DERATES PERFORMANCE.
This is why 10w50 may be preferred over 5w50 for W212 TT.
Last edited by CaliBenzDriver; Feb 21, 2025 at 12:32 PM.
I have NEVER seen that happen from simply idling (or any other condition). Any harnesses should be (and probably are) shielded from turbo heat. And, at idle, oil pressure is still sufficient to keep circulating through the turbos. They are also water cooled (primarily). Next time you come across someone claiming that their wiring harness or other parts were damaged by the turbo at idle, please post a link here.
At idle, the wastegate is open (by default), allowing most exhaust gases to bypass the turbine, so it is spinning minimally and not generating heat. Oil pressure is ~1 bar (15 psi) at 600 rpm.
My comments are based on stock turbos as from the factory. If someone has kludged up their settings with aftermarket "performance" components, then all bets are off.
A lot of GLS owners are getting melted harnesses, some are trying to fix using homemade heat shields - i might join that crowd, and also change viscosity at the same time
That's one nail in the coffin for M256 storing uncontrolled heat.
Why do they insist on storing extreme engine heat in dry pistons when all the evidence indicates poor reliability?
How are stuck rings supposed to be better ??
Now that's one thing you can focus on cancelling for greater results: "Normal Engine Heat" minus toasted oil-in-harness + ECU failures.
You can be the first one to enjoy M256 without the steaming heatsoaks... the key is to simply remove heat as its being produced at driving Rpm.
Storing heat in dry pistons leads to engine/tranny heat failures.
Find out what kind of stock oil is used then step up viscosity to lower spray Rpm... with trial and errors you'll be able to gain effective cooling and an effective protection film.
Are you going from 10w30 to 5w40 or from 5w40 to 10w50 ??
Likely from 5w-30 or 0w-30 to 0-40 and then my next change after that will be 5w-40, i have wanted to change oils for a while
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by exturnul
A lot of GLS owners are getting melted harnesses, some are trying to fix using homemade heat shields - i might join that crowd, and also change viscosity at the same time
It's never a bad idea to add shielding where you can. However, if there is heat damage, regardless if the car is moving or not, a complaint should be filed with Mercedes and the appropriate authorities. However, the vehicles affected may be too new to show a pattern.
My 2004 Audi TT with a K04 turbo (factory stock) has over 250,000 miles and has been chipped for at least 225,000 of those miles. It has heat shielding similar to those pictures from the factory. I still have the factory wiring harness, etc., though insulation has become brittle in some spots. Likely due to being 21 years old.
Throughout that time, the turbo never got hotter by mere idling once started and the car reached normal operating temperatures. If folks find the turbos on their Mercedes get hotter simply from idling, then that is a problem. I know some people have modified their main radiator fan to be always on and not turn off. That may be a "bandaid" fix to keep air circulating in the engine compartment.
Likely from 5w-30 or 0w-30 to 0-40 and then my next change after that will be 5w-40, i have wanted to change oils for a while
0w40 and 5w40 are literally the same.
What brings much needed quality to the oil you pick isnits base stock.
A group III "synthetics" forget it
A group IV: PAO from Amsoil
A group V: Ester grom Motul
I like your idea to measure live oil pressure
with stock conditions w30
with viscosity upgrade to 5w40
with solenoid off while stationed
we want to avoid starving head while pump output remains low.
It is highly unlikely you can cool pistons at driving Rpm on stock oil...TBD.
Last edited by CaliBenzDriver; Feb 21, 2025 at 12:57 PM.
unplugging squirters solenoid does enable squirting ?
OM651 diesel
I can confirm that the secondary piston squirter solenoid does enable squirting. The minor problem is that this port is now always open and does decrease the overall pressure to everything else after the squirters (Reviewed the oil channel paths). I have seen forum posts and videos related to this but it's all in Russian so I don't have enough feedback to verify if that route is safe enough. I have plugged that 2nd solenoid back in for now. I can see higher viscosity as a solution to mitigate that but it can only help so much.
With that I have decided to buy that guys mechanical valve from Germany and I will see how it goes. From his videos (mostly in russian) It allows piston heat transfer at cold start (thick oil, higher pressure) and once oil is warm the valve will close up and allow it to open up some as rpms increases, thus equally balancing the pressure going to the rest of the motor. I like that idea and the guy has been running it for a few years now without issue on his Diesel Vito
Will report findings once I receive it. Again this is for the secondary valve only found on diesels it looks like. I already have the primary oil pump solenoid disconnected and replaced with a solid piece from Mercedes.
A lot of GLS owners are getting melted harnesses, some are trying to fix using homemade heat shields - i might join that crowd, and also change viscosity at the same time
oh dear, I have a GLS as well, I should check on that...
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by exturnul
A lot of GLS owners are getting melted harnesses, some are trying to fix using homemade heat shields - i might join that crowd, and also change viscosity at the same time
From that thread, however, harnesses didn't melt. Seems like the insulation material disintegrated over time -- a very short time. The exposed copper wire corroded. Some comments attributed the quick deterioration to biodegradable materials used to meet some insane European eco-mandate. I'm planning that by the time I need a new car, I will be too old and feeble to drive.
I'm sure extreme heat may contribute to something like that, but I'm not convinced heat is the primary culprit. Owners wrapping they harness with heat resistant fabric may help, but it seems the bigger problem is with the insulating material. It would have to get damned hot in the engine bay to melt harnesses.
On my M276 bi-turbo, there is heat shielding already encompassing the turbos. As you can see, the turbos are not even visible from the top (where the spark plug harness is).
Right side of engine -- Left side of engine
Last edited by JettaRed; Feb 21, 2025 at 08:37 PM.
I can confirm that the secondary piston squirter solenoid does enable squirting. The minor problem is that this port is now always open and does decrease the overall pressure to everything else after the squirters (Reviewed the oil channel paths). I have seen forum posts and videos related to this but it's all in Russian so I don't have enough feedback to verify if that route is safe enough. I have plugged that 2nd solenoid back in for now. I can see higher viscosity as a solution to mitigate that but it can only help so much.
With that I have decided to buy that guys mechanical valve from Germany and I will see how it goes. From his videos (mostly in russian) It allows piston heat transfer at cold start (thick oil, higher pressure) and once oil is warm the valve will close up and allow it to open up some as rpms increases, thus equally balancing the pressure going to the rest of the motor. I like that idea and the guy has been running it for a few years now without issue on his Diesel Vito
Will report findings once I receive it. Again this is for the secondary valve only found on diesels it looks like. I already have the primary oil pump solenoid disconnected and replaced with a solid piece from Mercedes.
Great progress with diesel squirter control.
Keep in mind that when squirters open up it does change the VVT position.
This corrupts the learned ECU VVT PWM solenoid map.
> STRATEGIES (Diesel):
-- You want to spray cool your pistons at driving Rpm to prevent accumulating heat.
-- I think we said your camshafts timings are not hydraulically controlled, right? yes.
-- We know MB target is reduced oiling so opening squirters collapses head pressure...
so custom control your sprayers to be effective at lower Rpm but not low enough to significantly drop head pressure.
To turn around the low pressure setup, boost available pressure experiment with greater oil viscosity.
> Practically:
build up more pressure to be available at 1500.Rpm when you open squirters.
> SQUIRTERS Control:
Do you know if you have conventional 27psi ball-on-spring PLUS squirters solenoid
or solenoid only ?
Last edited by CaliBenzDriver; Feb 21, 2025 at 11:08 PM.
does anyone knows with unplugged solenoid does this could increase emissions, 2 days ago i went for annual technical inspection to give me approve that my car meets all requirements to be on the road and my emissions were nearly x6 times above (i know is due that i am running stage 2 with downpipes and that's the main reason but does the solenoid brings something to the emissions) it might be a stupid question from my side but just asking
does anyone knows with unplugged solenoid does this could increase emissions, 2 days ago i went for annual technical inspection to give me approve that my car meets all requirements to be on the road and my emissions were nearly x6 times above (i know is due that i am running stage 2 with downpipes and that's the main reason but does the solenoid brings something to the emissions) it might be a stupid question from my side but just asking
per Mercedes documents, reduced oiling reduces CO2 by 2%. It’s not the solenoid.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
