When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have watched this forum close over the past year and your progress!. Its insane how informative you are. I have a C400 with the M276 BiTurbo.
I just pulled the plug and would you advice to change the oil to Motul 8100 API-SP SAE 5w-50?. Im on 0W-40 atm ..
Good move to MOD-1
Personally I would not recommend skipping from 0w40-SN to 5w50-SP. No question MOD-X will yield awesome power but you may favor engine safety over cyl. chaos....
You are aiming for a true ring seal not just viscosity alone. Unstable cylinders timings can hurt specially with high power output.
I think it's best to give your piston RINGS time to get wet, cooled and cleaned up if possible.
This is exactly like taking a couch potato on a marathon course: better ramp up the workout level.
What gives greater power are exact timings for full burn and strong maps. With drafty cylinders that's impossible. The result of drafty cylinders is lean misfires.
When you "cheat ring seal" with more effective viscosity the ECU hands out more fuel, engine get more power, you push into higher Rpm but stuck rings seal is weak so uneven cylinders timings are unpredictable.
This is especially true during oil transitions!
Smaller step ups are better that giant ones. Let the engine improve and ECU adapt to new conditions. This transformation takes time. I think its best not to rush it.
The issue with unbalanced high output is the soft conn rods bearings. You want the stress shared across all cylinders, not just high stress on few cyls. Let the "vibration level" be your guide: balanced contributions have NO vibration, is quiet and strong.
Transitioning to MOD-1 the engine is still inconsistent below 2000.Rpm where VVT begin to be predictable.
You can expedite upgrade but then be sure to stay away from high-rpm ( < 3kR.)
It's experimental, you're the test pilot.
Last edited by CaliBenzDriver; Jul 10, 2025 at 05:49 PM.
I have watched this forum close over the past year and your progress!. Its insane how informative you are. I have a C400 with the M276 BiTurbo. I just pulled the plug and would you advice to change the oil to Motul 8100 API-SP SAE 5w-50?. Im on 0W-40 atm ..
Give it a slow steady transition, once you switch to 5W-50, you would not want to go above 4000 RPMs for a while as the oil works its way to help reseal.
Personally I would not recommend skipping from 0w40-SN to 5w50-SP. No question MOD-X will yield awesome power but you may favor engine safety over cyl. chaos....
You are aiming for a true ring seal not just viscosity alone. Unstable cylinders timings can hurt specially with high power output.
I think it's best to give your piston RINGS time to get wet, cooled and cleaned up if possible.
This is exactly like taking a couch potato on a marathon course: better ramp up the workout level.
What gives greater power are exact timings for full burn and strong maps. With drafty cylinders that's impossible. The result of drafty cylinders is lean misfires.
When you "cheat ring seal" with more effective viscosity the ECU hands out more fuel, engine get more power, you push into higher Rpm but stuck rings seal is weak so uneven cylinders timings are unpredictable.
This is especially true during oil transitions!
Smaller step ups are better that giant ones. Let the engine improve and ECU adapt to new conditions. This transformation takes time. I think its best not to rush it.
The issue with unbalanced high output is the soft conn rods bearings. You want the stress shared across all cylinders, not just high stress on few cyls. Let the "vibration level" be your guide: balanced contributions have NO vibration, is quiet and strong.
Transitioning to MOD-1 the engine is still inconsistent below 2000.Rpm where VVT begin to be predictable.
You can expedite upgrade but then be sure to stay away from high-rpm ( < 3kR.)
I've un-plugged the oil pump on my M278 and getting ready to do it this weekend on my wife's M276. It is a MY 2019 and I'm trying to find the dummy solenoid to plug her plug into to avoid the CEL. @OldManAndHisCar posted a link to Aliexpress, but it is no longer valid. Does anybody have a good link for the dummy solenoid ?
Thanks.
I've un-plugged the oil pump on my M278 and getting ready to do it this weekend on my wife's M276. It is a MY 2019 and I'm trying to find the dummy solenoid to plug her plug into to avoid the CEL. @OldManAndHisCar posted a link to Aliexpress, but it is no longer valid. Does anybody have a good link for the dummy solenoid ?
Thanks.
You can buy the oem part if you are in a hurry, the site you mentioned will take a month or two to arrive.
I switched to 5w-50 over the weekend and tried to get in there to unplug the oil pump solenoid and just could not do it, the way it is stuck inside there between the crank pulley and all. I tried removing the pan and going from underneath, but the fan is in the way, and from above there's just no way, I can barely get my hand on it. I looked into the electrical connector pliers (that at my age I should have bought years ago) but they all look like they are 6-8" long and wouldn't fit in there between the fan and the block anyway. How did you all get in there to unplug it? Is there a particular set of pliers that works?
I switched to 5w-50 over the weekend and tried to get in there to unplug the oil pump solenoid and just could not do it, the way it is stuck inside there between the crank pulley and all. I tried removing the pan and going from underneath, but the fan is in the way, and from above there's just no way, I can barely get my hand on it. I looked into the electrical connector pliers (that at my age I should have bought years ago) but they all look like they are 6-8" long and wouldn't fit in there between the fan and the block anyway. How did you all get in there to unplug it? Is there a particular set of pliers that works?
You have tried to reach the solenoid connector from top + bottom without success.
You know there is always another way!
If your engine type does not CEL (need dummy load) - You may want to simply cut-off one of the two wires near the connector and call it a day.
All that needs to happen is solenoid stay disabled being out of circuit: One open wire does that.
I switched to 5w-50 over the weekend and tried to get in there to unplug the oil pump solenoid and just could not do it, the way it is stuck inside there between the crank pulley and all. I tried removing the pan and going from underneath, but the fan is in the way, and from above there's just no way, I can barely get my hand on it. I looked into the electrical connector pliers (that at my age I should have bought years ago) but they all look like they are 6-8" long and wouldn't fit in there between the fan and the block anyway. How did you all get in there to unplug it? Is there a particular set of pliers that works?
I also linked some of the helpful posts from the big thread by forum member CaliBenzDriver and others here (compilation), it is not inclusive though, read OP's post there and then read other posts there: https://mbworld.org/forums/c450-c43-...-oil-flow.html
With these types of connectors, it is best to use a hook tool.
Last edited by W205C43PFL; Jul 20, 2025 at 07:06 PM.
Please read the previous mentioned linked thread, there are posts of which links to how the connector is, as you know, it is a two stage process (MB really like 2 stage of everything don't they, solenoids and connectors?), stage 1 you hook the locking tab/pin/clip and then you pull as stage 2 (at the same time.)
Last edited by W205C43PFL; Jul 20, 2025 at 07:30 PM.
I did manage to get a hook in there to pull out the gray lock tab, just can't get a hand in there to squeeze the connector to pull it apart. I am wondeirng if maybe when i go to replace my cam phasers I just remove the fan. That may give me a ittle more room for both jobs.
M276.9 is easy to acces the oil solenoid connector.
M276.8 with 3.0 Turbo is more difficult as the aftercooler boxy body need to be removed.
You must work from under the car, unless you hand is very-very long.
Remove all under carriage protection plastics and steel plate and if you have protection steel plate for power steering, remove it too.
If you can't remove this connector, I have big doubt you can do VVT ( camshaft adjuster sprocket ) properly. You asked on another post about VVT replacement.
Wait, that steel plate right under the crank pulley is removable? Dammit. That would have been easy then when I was under there. Thank you!
Originally Posted by S-Prihadi
M276.9 is easy to acces the oil solenoid connector.
M276.8 with 3.0 Turbo is more difficult as the aftercooler boxy body need to be removed.
You must work from under the car, unless you hand is very-very long.
Remove all under carriage protection plastics and steel plate and if you have protection steel plate for power steering, remove it too.
If you can't remove this connector, I have big doubt you can do VVT ( camshaft adjuster sprocket ) properly. You asked on another post about VVT replacement.
I was able to get in from the top side in our '14 E350.
If I recall, I couldn't get it by going straight down, so I went from the passenger side - reaching under the some hoses and then over to the solenoid.
Had to do this twice, as the $&%*$ dealership reconnected it at the last service.
(Be sure that the engine is cold - very unpleasant otherwise)
Wait, that steel plate right under the crank pulley is removable? Dammit. That would have been easy then when I was under there. Thank you!
yes, of course.
If your steel plate is the same version like mine, galvanized color, it uses 6 bolts , M13 socket and it is quite heavy. 20 lbs easy.
Power steering black steel guard, mine is EPS, M16 or M15 socket, 4 bolts, light weight this one.
Long plastic cover under the bumper, like 11 pcs or so, M8 wood screw type not machined screw. Be gentle on them.
HI All- Thank you for al the in depth info- there is a lot to digest from some very smart minds !
I have a 516 box van camper here in OZ with OM651
I have trolled and trolled and come to the conclusion that Unplugged = fail safe mode and allows full oil pressure to rotating assembly and critical parts including piston cooling jets
Is this correct ?
this will also log faults but not activate Engine light
I would appreciate a reply from one of the Tech Gurus on here to releve my blood presure hhaha
I will post this generic reply on a couple of sections in hope it Pings someones inbox and a reply is forthcoming - Apologies for multiple replies if everyone on the thread gets pinged in the inbox
many thanks Jess
HI All- Thank you for al the in depth info- there is a lot to digest from some very smart minds !
I have a 516 box van camper here in OZ with OM651
I have trolled and trolled and come to the conclusion that Unplugged = fail safe mode and allows full oil pressure to rotating assembly and critical parts including piston cooling jets
Is this correct ?
this will also log faults but not activate Engine light
I would appreciate a reply from one of the Tech Gurus on here to releve my blood presure hhaha
I will post this generic reply on a couple of sections in hope it Pings someones inbox and a reply is forthcoming - Apologies for multiple replies if everyone on the thread gets pinged in the inbox
many thanks Jess
Jess,
Some recent developments to be aware of.
Mercedes is now updating their coding in EVEN their older cars. Currently and in the future, when you bypass the critical design element of the oil pressure control solenoid in the engineered function of the MB oiling and VVT system. It will NOW trigger a code and can no longer be bypassed. That is a newer development at least here in the US and Europe. If you’ve been to the dealership lately, it’s possible you may have the updated ECM firmware.
Bypassing parts of engineered functionality of the oiling system will NOT prevent Bore Scoring!
The myth that the tiny stream of oil, aimed specifically at the underside of the piston crown, in order to cool the cylinder charge, somehow will magically prevent bore scoring has been de-bunked and lost in the mess of a thread. It does not and will not. If this was even an engineering consideration, the oil squirters would be pointed at the thrust side of the cylinder bore/piston.
There is mounting evidence disconnecting the oil pressure solenoid, may do more harm than good at this point. Lower tensioners may be wearing at an accelerated rate. https://mbworld.org/forums/w212-amg/...ml#post9200847
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.
