Tasos specifically talked about full-pressure cold-starts in Antartica (my exaggeration) as being potentially harmful to the pump. And I also don't like the idea of pressure surge suddenly at a certain RPM. The test I did with the external pressure gauge on a warm engine with the solenoid disconnected showed a smooth increase until the maximum pressure (~47psi) at ~1500 RPM. While my absolute psi measurement may have been crude with an inexpensive pressure gauge, it still showed well controlled behavior of the oil pressure.

 

@S-Prihadi , with regard to the white paper, again the goal is engine efficiency, which sounds nice, but is misleading. Normally, improved efficiency implies improved power, so it sounds nice. But there is an intentional disregard for (i.e., ignoring) unintended consequences for the sake of better gas mileage. Reading between the lines, the obfuscation of consequences becomes readily apparent once you start looking for key words and phrases, like "improved efficiency" and "reduced energy input". Never is mechanical longevity mentioned as a goal.

That's like pure water is the best medium for heat transfer in the cooling system, but using only water can lead to parts corrosion and even freeze damage in cold climates.

 

Jetta,

What I want to show in the VVT white paper is how painful it is for them VVT OEM dealing with newer engines having reduced ( regulated ) oil pressure.
So even the VVT OEM is complaining
Their words is kind, they said CHALLENGE .... lol

 

Well, duh, that is simply "Woke Wording" as to not offend anyone. Now, who would like an undeserved participation trophy? ;-)

That said, like so many others. I am three weeks into having mine disconnected and can not wrap my head around why the car accelerates in "C" better (understand the physics and all)....just odd that MB would do that right out of the gate (I have to assume they KNEW scoring would be an issue - AFTER the warranty period if all went well for them).

 

Is cylinder scoring a problem for non-AMG engines?

I mentioned before, high performance cars are expected to wear out sooner than regular cars. So, attributing cylinder scoring to the bogus efforts to squeeze out a one or two more MPG is purely speculation (in a courtroom) or anecdotal, at best. Now, if someone comes back and shows similar scoring on a non-AMG engine, my reasoning doesn't work.

Or, since this type of 2-stage oil pump is used by other manufacturers, do they show similar scoring problems? If so, then we have a stronger case for the oil pressure management scheme being the culprit. If not, then we have narrowed down the problem to AMG engines, which is a big problem for AMG.

 

As far as I know, M278 is a "run-of-the-mill MB engine" and is well-known for cylinder scoring. Perhaps we need other criteria to separate them, NA vs Turbo?

 

All we can do around here is speculate. Some of our speculation can be informed by certain engineering data, experiments, anecdotes or other engineering reasoning/logic/intuition.

Yes, non-AMG engines score. Do they score as often? I dunno, probably not?

Mercedes is not the only automaker to use, and have difficulties with, cylinder coatings. Mercedes is not the only automaker to use, and have difficulties with, direct injection.

In the critique community, we commonly see issues being caused by a multitude of issues. There is almost never a single variable smoking gun to make all of our problems go away.

Some variables that I believe contribute to scoring:
- Driving hard on a cold engine (differential thermal expansion)
- Extremely long oil change intervals and perhaps some oils are better than others
- Fuel quality (maybe not much of an issue in most Western countries, but I've heard rumblings of sulfur content being a contributor, for example).
- Direct injection itself tends to aggravate cylinder scoring issues due to wash down
- Cylinder coating material choice AND/OR variance in application (i.e. QC)
- Piston/cylinder tolerances
- A piece of debris (like a chunk of carbon that falls off an intake valve) gets in there and you can imagine the rest
- Yes, perhaps this oil pressure control strategy also contributes
- Detonation, poor gas and/or aggressive tunes can rock the piston, damaging the cylinder
- It's been speculated by Tasos (and others) that the M278/M157 rod/piston geometry is the opposite of what it should be (in terms of which end is fixed and which end has axial play at the bearing)
- I'll make one up, but it's probably worth something: open deck block designs, such as the M278/M157, can have less stability in the bore over time and over stressing conditions

Now is one of these maybe a stronger contributor? Sure. Is it just ONE of these things? No chance in hell.

 

It would be interesting to see some statistics regarding M278/M157 longevity. While the issues regarding bore scoring and such are well known (at least on the internet), is it really as big a problem as has been communicated on these or other forums, or are we just hearing from the unfortunate few?

In this day and age, cars last about 200k miles on average. My last 2500 HD Chevy truck had almost 400k miles on it when I sold it - the engine and trans were still original and I towed heavy with it (6.0L gas and 4/spd heavy duty auto). The truck is still going.

From a reputation standpoint, I’d think that Mercedes-Benz would want to maintain their claim to superiority - there are cars out there with well over a 1m miles. Supporting items might break, but the drivetrains have stood fast.

So what’s the real answer?

 

Generally I think powertrain longevity has decreased as we entered the aggressive fuel economy/emissions regulation era (circa 2005 for CAFE in the US).

There is no free lunch. You can have efficiency, cost, reliability or performance. Pick.....two? Sometimes three?

I think the issue is probably overblown, yes, but there are real casualties annually for the unfortunate few.

My list wasn't intended to make any declaration on actual statistics, only possible causality for when an issue actually occurs.

 

Someone asked about other Manufactureres using 2 stage oil pressure solenoids. Toyota uses that on their 3.5 L v6 in several models ( SUV and cars trucks )

Issues with knock on startup, VVT ( oil pressure fed ) and piston slap . Note just like MB there is NO oil pressure sensor, its just a ECU routine. There is a oil light but its just a on off switch. Cylinders are Iron ..NOT coated....

Yes I have a 2020 Toyota Highlander FWD with the v6,yes it has teh solenoid, No i have not tried to disable that as it is unknown what position it defaults to.

Link for you guys to the Care Care Nut going over issues and engine removing :

 

To be honest, I was shocked when I read about the M276/M278 using an open deck block/cylinder arrangement. I rebuilt 3 or 4 Renault engines in the 80's that used the open deck, replaceable steel sleeve and they were a nightmare. Usually, due to overheating, poor assembly, or overstress (due to "hot rodding") those engines will leak water/coolant between the block and the sleeves beside the classic blown head gasket. I assumed MB had figured out the "open deck" issues and moved into that approach; however, 300+HP vs 100+HP is quite a different beast to tame.

Interesting you mention that as well, similar to Tassos when comparing M177 vs M157. He said something about a closed deck preferable to an open deck.

 

Glad to see the discussion moving forward. Many of the possible contributors that @kevm14 mentioned are within our control to counteract, such as long drain intervals and driving hard when cold. I'll be changing plugs soon on both my M276.825 3.0 bi-turbo and my M276.925 3.5 NA cars. I'll try to get a scope inside the cylinders to see what they look like.

I gotta be honest with you guys that I don't feel so bad about having a V6. For 99% of the driving I do, 400hp and Agility mode are fine. I don't challenge Dodge Demons, Corvettes, 911 turbos, or even Honda Civics. I'm not a wimpy driver, so more power would be more opportunity to get into trouble. (That's my story and I'm sticking with it.)

 

, I am with you 100%. I do not drive WOT, but WOB (wife on board) and she does not like me above 100mph, so I have to behave . Even with a V6, I got my $300+ ticket already, and I do not plan to get another one.

 

I think these engines fare better than average considering open deck and power levels. I want to say the "typical" open deck casualty is head gaskets and I have pretty much never heard of that on these. I believe the M113 and M273 were also open deck which is where the M278/M157 lineage actually dates back to.

 

Dodged a bullet.
I used an autometer 2277 m12 adaptor several weeks ago to check my oil pressure with a mechanical gauge to verify that this works on the m157.
This past weekend I attempted to reinstall the gauge in order to make a video showing the pressures with and without the mod, but well before the threads were close to bottoming out it broke. I think what happened was this gets installed behind the charge pipe and i was using a 15* swivel extension that must have needed 16* or something lol. luckily it was only 2/3rds threaded in, so it was easy to unscrew the broken piece by hand. Upon inspection, the adaptor is very thin in the place where it broke.
Just a word of caution if you're using the same adaptor, would have been terrible and messy to happen while driving.

Anyway, Calibenz, S-Prihadiand JettaRed videos and research have provided an overwhelming amount of evidence for me.
Taosos and others concerns have been addressed IMO.
1. To much pressure on cold start ups? Negative, in fact the Mercedes description back up by real world videos here show the engines cold start WITH high pressure and about a minute later drop to low pressure on a cold start. Thus there is no extra strain on the pump.
2. Double pressure? (2 bar vs 4 bar) just like I and other here though, oil pressure is always linear (climbs with rpm until the pressure relief setting) its just linear under high pressure or low pressure. The exception being with the low pressure version there is a massive jump, i would call it a shock or stress at 3500rpm. If there is anything in this discussion that IMO could be harmful to the pump is would be this on/off function.
3. oil killer? Im going to disagree with an asterix. Oils are very good these days. Pressure does not kill oil, heat does. Does this mod create more heat? no. In fact i would argue the stock setup creates more heat. two examples, Imagine a scenario after an enthusiastic drive above 3500 rpm. The oil pump function would be identical in both scenarios, but now youre just cruising at 1500rpm. In the normal function, the oil is flow is reduced through the cooler, thus is cools slower. Also this pistons are now allowed to dry, thus they heat up and get very hot, I would guess 450+? so next time the rpm goes over 3500rpm and the piston jets come on, that oil is being sprayed on very hot metal, which would over heat that oil, causing it to prematurely break down.
The asterix is simply i agree, 10k miles is way to long between oil changes. longest ive ever gone on any car is 5k.
4. lastly, its hard to "override" something i am sure MB spent millions to engineer and create. extreme caution is advised and this thread is evidence of it. another thing that came to mind is who else does this? is the oil pump in my F355/F430 like this? what about lambo, corvette, porsche, r8s, etc? nope. how about any other ultra high performance or race car? nope.

 

Inside the LT2 | Issue 134 | Corvette Magazine (corvette-mag.com)

​​​​​​​It's more common than you think. It's just that the Germans tend to lead the way (aka take the risks) when it comes to stuff like this. Sometimes it pays off, sometimes it doesn't.

 

Yeah, right. A performance car owner is worried about the cost of 2 quarts/5K miles, and an extra gallon per fuel tank every fill.

Also, the LT2 has a rev limiter at 6600 RPM. Does it mean the pump only works at full pressure between 5500 -> 6600 RPM?


I think the bean counters and the marketing boys are running the sanatory these days. They should just stay away from the engineers and let them do their work.

 

Toyota licenses its proven designs from best German companies.

They having the oil pump control solenoid does not guarantee they abuse it.

You can most likely expect a failsafe design like we have.

> How to be positively proactive:
​​​​​​Use a scanner to track the status of your pump solenoid :

• idle RPM
• 1500 RPM
• 4000 RPM

There's a chance they don't randomly abuse low pressure to create chaos.

Double check when your TOYOTA solenoid is active.

++++++ VVT Design :


"long story short!!'
@S-Prihadi This enlightening white paper has all the smarts necessary to understand the importance of oil pressure for VVT operations.
It even talks about the 3D mapping that I think bugs down with random oiling.

I did not know any of that when I pulled the mystery plug. It's good to read confirmation

Low pressure is clearly identified and solutions discussed. The hydraulic VVT phasers are identified as economical compared to better electrical VVT with fast response regardless of pressure consideration.

This was an opportunity for us to kill two birds with one stone. We cancelled both laggy acceleration performance and superheated dry cylinders.

I think that's a whole lot of good at once.
​​​​​​

 

This definitely looks like a case of AMG developing the engine and software the way they desired it, then had MB Corporate come back through their design to add in these little emissions/"efficiency" tidbits. Given that the AMG designed M156 does not have any design or emission/"efficiency" design, I doubt they thought of adding or enabling this solenoid function. As has been detailed here, the VVT and the overall engine health can only be benefitted and ensured with proper lubrication. There is no reason to be starving parts of the engine of lubrication while ALSO programming the shifting behavior to keep the RPMs below the RPM threshold that allows full pressure oiling.

As I've outlined before, these types of cars post-AMG being acquired are almost all designed to truly last the life of the warranty period. MB could care less about any of us who bought these second or third-hand. The cylinder scoring issue would either 1) be covered under their warranty if discovered while on their leasing program or still under warranty 2) only truly become a problem after the warranty while being driven to a standard car's usage (commuting, a few long distance trips per year, etc.). The long-term health and viability of these platforms are essentially only theoretically known based on calculations and limited accelerated testing periods done before production.

As I've also stated in here before, these types of discoveries and innovations like the new intakes, cifdig's intake/charge pipe he's developing, the Blackboost thermostat mod, the always-on fan mod, this mod, etc are essential for keeping these platforms alive in an era when they are essentially built to be expendable.

UPDATE ON MOD:

I've been unplugged for about 1500 miles now.

Throttle response is still astoundingly improved, it just picks up and goes even at lower RPMs.

The lurching/surging when taking off from a stop when in S/S+/M modes still has not occurred since unplugging.

The oil temps are much more stable, especially when in M mode and staying within the fun RPM range. There is fewer dramatic spikes in temperature when going to redline and when they do occur, they equalize much faster than I prior to unplugging.

The most critical to engine health I have noticed is that once I park the car, the engine area of the car no longer feels like blast furnace when you are near it. This definitely tracks with the fact that the cylinder walls are now getting oiled across the RPM range, thus allowing the oil to transfer heat away from the block through the oil cooling system. I'd theorize that this will significantly extend the life of the plastics in the engine bay that are no longer being cooked and experiencing such severe heating cycles and heat soaks.

I have noticed a noise when coming of the gas and letting the RPMs fall while coasting with no throttle applied. I don't think it's related to the mod and I hope it is not of concern. But that is to be diagnosed later.

 

The M176 is said to be an inherently AMG design (meaning the M176 and 177 were designed at the same time by the same people, more or less). It uses this 2 stage oil pump system.

I don't know why everyone looks past government regulations. They created the entire environment that incentivizes manufacturers to make decisions like this, chasing fractions of an MPG. GM AFM, high coolant temps on the ragged edge of overheating, SUPER low tension rings and questionable cylinder coatings, direct injection, below-reasonable oil capacities (looking at you, Honda). Oh I almost forgot, TOTALLY unreliable diesel engines which used to be the most reliable thing you could buy. Surely, the consumer would never trade off 0.4 mpg for engine longevity concerns. The argument is, what's a failed engine when we are saving the planet? What's a dead ICE when the ICE is the root of all evil? This is the world we have created for ourselves.

 

That's exactly my point and I expounded upon that in an earlier reply. They mandated "efficiency" percentages for a manufacturer's fleet produced per year. This is why they can still make their "halo" cars that are still the V8s and above. It's why the lower-tiered OVERSTRESSED engine designs slow crept up the line-up from cheapest to most expensive of the MB (and other manufacturer's cars).

Which is why I said it looks like AMG designed the whole system of this car to function like it is now with the solenoid unplugged, i.e. no poor throttle response, no lurching/surging when in sportier modes. The engineers who CARED about designing an awesome engine and platform in the performance spirit, made what they wanted, then the MB Corporate overlords came through and put in all their emissions and "efficiency" nonsense.

And yes, the ultimate goal of governments is for you to HAVE to ditch your ICE car simply because you cannot repair the issues that they are forced to inherently design into them now. It's the same effect of the insane Oil Change Intervals (OCI) that these manufacturers are doing. Plus, all these "sealed" systems or the "Lifetime" fluids. HAHA yes, the "lifetime" is definitely not much more, if not rated to the exact mileage of the manufacturer's warranty period. People buying these new cars are buying a disposable item, meant to last only to a certain failure point that will ultimately make the cost of repair/replacement not worth the investment for all but the diehards (basically where the W212 user base is currently). Almost every W212 BiTurbo engine being bought the last few years is now at a point in life that approx. $2-8K worth of preventive maintenance and service intervals are due. That's almost an eighth to a quarter of the value of these vehicles nowadays. It will eventually ONLY be the most diehard enthusiasts who are willing and capable of rebuilding this engine and doing/paying for electrical work to be done that will hang onto these.

Heck, I had a guy who wanted an oil change to be performed after a 1000 mile break in period he had done. He bought a brand-new Tacoma and when he asked the dealership to perform this, they refused because it wasn't in Toyota's procedure to allow it. Every engine should have a break-in period with an oil change to follow. Just goes to show that even the "reliable" brands are now buckling to governmental pressures.

 

I’ve noticed the same… but not all the time. I’m pretty sure it’s the ABC on mine. It followed the shudder and vibration that came with my bad pulsation damper. Changed the damper… mostly quiet but sometimes is complains just a little. My SL drives like an absolute
beast and does what it supposed to do so I’m definitely not concerned.

 

Because some of the government regulations are impossible to meet w/o cheating? VW was just caught, but manufacturers cheat to meet regulations

https://www.reuters.com/business/aut...ns-2022-11-17/

Sometimes they cheat the regulations, sometimes they cheat us by producing cars with an expiration date.

 

Hey guys…

Looking at fb this morning (M157 marketplace), someone chimed in to say they changed their oil and unplugged. After a short time, it was noted that the freshly changed oil was considerably darker than normal (the user reported that he plugged the solenoid back in). Anyone experienced similar?

My thinking is that the detergent package is doing its job cleaning all the crap off the pistons, but without seeing it/smelling it for myself, I can’t really say. If oil temp is stable, then it shouldn’t be a “cooked oil” situation - just cleaning. My thought would be to perform more frequent oil changes to see if the condition improves.

Anyway, just an interesting observation. Thoughts?

 

Thank you for that information, and I agree with you that likely the engine is being cleaned now, in particular the piston rings.

I will ask my Indy to comment on the oil color or else. He usually comments on the quality of the replaced oil. I already have 600 miles on mine, and due for an oil change this week anyway.