2015 GL450 Running Rough




heat stressed pistons cracks - Some bs excuse for improper car exploitation. If your sticker at fuel cap says "92 and above" so your lowest choice would be at least Sam's Premium 93 or above. Splitting tank in half with regular or riding regular isn't going to work. Cracked pistons due to detonation only.
scored dry cylinder walls, - big time bs, just because "he had a dream", reason for scoring is wear of protective piston skirt coating, which is due to excessive carbon buildup, which is due to many factors, but the major one is burned oil - which is basically too much of it
leaking chain tensioners - bs, tensioner going out because of constant pulsing feedback from valve train, as a matter of fact instead of suggested timing chain replacement i would just replaced tensioners first, because most of them stuck in certain position due to internal wear
knocking VVT worned pins - bs, pin only used during startup, once oil pressure buildups it is out of lock position, camshafts on m278/m276 is not VVT or VTEC kind, angle continuously monitored and adjusted, not in steps,
dry shaved camshafts - bs, just a metallurgy of manufacturing process,
seized HPFP dry pistons - bs, - never seen one even on dead engines
vaporized oil coating valves, 02, cats - bs, guys obviously don't know how this engine operates or designed
burned CPS feeding oil-in-harness... - some bs words to make himself an export on subject he barely knows.




It will seize, like any other engine. Specifically speaking it will spun last main or cylinder 4 and 8 connecting rods due to farthest distance from oil supply
Do piston squirters shut off below 20Psi with individual ball-on-spring valve?
Same way as 1000 other cars by other manufactures, just to make sure you don't loose oil on idle
How do squirters only "cool extreme loads" - Normal loads no need oiling ?
Oil squirters initially been implemented on diesel cars to cool down pistons, later been added to AMG kind engines, and with the progress took a place with any high performance builds and regular turbo cars as well. However In extreme turbo boosted Coyotee's sprinklers blocked off due to excessive oil drag force on pistons to save some horsepower. Depends on situation, in this particular engine they just cooling pistons, runoff from connecting rod bearings will have more than enough oiling on cylinder walls.
Do you think normal oil pressure can help restore normal wear schedule?
Would not. Wear due to excessive carbon buildup and improper exploitation
Do you think it is beneficial to drive on low-oil pressure??
Just save energy here and there, as long is supply enough oil to keep oil wedge - you ok
Why is so much burning oil getting vaporized through the intake ?
That is main question of the subject guy have no f-king clue. Mercedes implemented no return fuel system, so your runoff from fuel injectors goes back into crankcase, and then evaporates back into intake through positive pressure crankcase ventilation. For that particular reason latest copies of owner manual specifically says - in operating in cold environment wait till engine reaches full working temperature, to make sure that you not saturating engine with injector runoff gasoline. That is the reason for oil smell being gassy and your engine looking extremely clean after long abuse.




Here is an example of detonation damage to MB piston. This is 4 cylinder turbo banger 250/450AMG. And that is driving on regular gas. The real reason - since this is cast iron cylinder engine.
What else can you tell about this piston from second picture?




heat stressed pistons cracks - Some bs excuse for improper car exploitation. If your sticker at fuel cap says "92 and above" so your lowest choice would be at least Sam's Premium 93 or above. Splitting tank in half with regular or riding regular isn't going to work. Cracked pistons due to detonation only.
scored dry cylinder walls, - big time bs, just because "he had a dream", reason for scoring is wear of protective piston skirt coating, which is due to excessive carbon buildup, which is due to many factors, but the major one is burned oil - which is basically too much of it
leaking chain tensioners - bs, tensioner going out because of constant pulsing feedback from valve train, as a matter of fact instead of suggested timing chain replacement i would just replaced tensioners first, because most of them stuck in certain position due to internal wear
knocking VVT worned pins - bs, pin only used during startup, once oil pressure buildups it is out of lock position, camshafts on m278/m276 is not VVT or VTEC kind, angle continuously monitored and adjusted, not in steps,
dry shaved camshafts - bs, just a metallurgy of manufacturing process,
seized HPFP dry pistons - bs, - never seen one even on dead engines
vaporized oil coating valves, 02, cats - bs, guys obviously don't know how this engine operates or designed
burned CPS feeding oil-in-harness... - some bs words to make himself an export on subject he barely knows.
You obviously have hands-on experience so I respect your position.
These cars as not stacks of parts. The dynamic system interactions are essential. Try to pick-up what you ignore when opportunities knock... I won't attempt to sway your bubble - It's fine.
I don't think engines blown by cheap gas are related to MB oiling issues. The vast majority of Benz owners are educated, not careless ignorants.
Last edited by CaliBenzDriver; Oct 19, 2023 at 11:08 PM.
M17x and M256 seem OK so far. It seems like a stretch to think these will be OK long term.
An MB with M17x and no 48V system is the only current MB I would consider - not many models to choose from. W205 C63, early W213 E63 post-M278, late W222 S560.
But oil vapor separators need to changed as regular maintenance items, or blow out the RMS.
Such garbage.
Last edited by chassis; Oct 20, 2023 at 04:04 AM.
I would also check to see what codes are being thrown to make sure the timing is within specs. If indeed the shop replaced the camshaft they should have also advised to replace the adjuster as it was likely the cause of the rattle. The chain tensioners have been attributed to the rattle but as I understand it, they are not usually the culprit. Have a reputable shop take a look at this. They will pull the codes and also turn the engine to see if the adjuster is faulty.




I would also check to see what codes are being thrown to make sure the timing is within specs.
If indeed the shop replaced the camshaft they should have also advised to replace the adjuster as it was likely the cause of the rattle.
The chain tensioners have been attributed to the rattle but as I understand it, they are not usually the culprit. Have a reputable shop take a look at this.
They will pull the codes and also turn the engine to see if the adjuster is faulty.
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