£ C43 £ AMG £

Same applies to all Mercedes that have NIKASIL coated bores, this is a copy and paste below.

Nikasil cylinder bore linings are particularly vulnerable to fuel (gasoline or petrol) with a high sulfur content. The sulfur in the fuel breaks up the Nikasil lining in the cylinders, thus causing a loss of compression. Once the lining is damaged, excessive bore wear of the soft, underlying alloy occurs very quickly. Some Nikasil engines have failed in as little as 30,000 miles. And the effect is cumulative, so if the engine has ever been run on high sulfur fuel, the damage may already have been done and premature bore wear may result.
Some symptoms of the Nikasil problem are rough running at idle and difficult cold starting, both due to loss of compression. In severe cases, the loss of compression is so bad that the engine loses power. Oil consumption increases dramatically as oil is sucked up the side of the leaky pistons. In extreme cases, the compression decrease is so severe the car will not start in cold weather, especially M52 6-cylinder engines.
Over the years, BMW has provided replacements with steel, cast-iron or Alusil lined engines, at considerable cost to the manufacturer. Often, disgruntled owners have borne the brunt of these replacement costs, and prospective buyers are at risk, too.
The Nikasil coating process was developed by the German firm Mahle, originally for use in the Mercedes Wankel rotary. Audi, BMW, Ferrari and Jaguar have all used Nikasil engines in their production cars. Porsche used Nikasil in their turbocharged 917 - 935 series of race cars. In racing two strokes, both Morbidelli and Rotax have had great success with Nikasil. Nikasil has been used in thousands of professional grade chainsaws, motorcycle and marine engines, and even many NASCAR Winston Cup and Formula One engines.
Nikasil has been used in high performance engines because it allows the total elimination of poor-cooling cast-iron, and it is harder and more oleophilic (oil-liking) than cast-iron. Nikasil offers superior lubrication, reduced friction, and superior wear characteristics.
The Nikasil cylinder coating is a nickel and silicon carbide matrix coating about 0.07mm (.0025-.003") thick. The Nikasil treatment coats a layer of nickel-silicon carbide, usually by electrolytic deposition, to the inner surface of aluminum cylinders. The nickel matrix is very hard, yet it is relatively ductile. Dispersed through the nickel are particles of silicon carbide less than 4 microns in size. These extremely hard particles make up 4% of the coating and form a multitude of adhesion spots where oil can collect. Beside providing a long wearing surface for the piston and rings, the silicon carbide particles contribute to longer engine life by ensuring good cylinder lubrication.
So why is there a problem? BMW reportedly did not discover the problem with Nikasil in their original testing because they used only high-quality fuel. Sulfur should be extracted from fuel before it is used, but since it is a costly process, oil companies may not remove as much as they should. Once BMW was aware of the Nikasil crisis, BMW replaced the cylinder blocks and also tried to ameliorate the problem by re-programming the DME to ensure higher combustion temperatures.
Take the vehicle to a qualified mechanic for a "leakdown" compression check. The leakdown test detects a lack of effective sealing (loss of compression) in one or more cylinders.
If you take the vehicle to a dealer, the mechanic can quickly check the idle quality using a BMW diagnostic computer system. BMW extended the warranty on Nikasil engines up to 6 years or 100,000 miles, whichever comes first.
Remember, the higher the octane, the lower the sulfur. If the previous owner had always used high octane fuel, then you may never have a Nikasil problem. Beware if the prior owner always bought the cheapest fuel!
Because of the quality of the fuel in certain locations, some areas are more likely than others to have high sulfur fuel. Unfortunately, the USA and the UK are two of these areas. These also happen to be two of BMW's largest markets! Incidentally, Germany and Continental Europe appears to be largely unaffected by the Nikasil problem.
Everything else being equal, if you are in the market, you want a car with an Alusil engine (the M62).

shooter

This was an interesting read. As I'm newer to the German car market, is there a good source that described which cars have which engines? In short, my '08 E63, what the heck is in there?

£ C43 £ AMG £

All 55k engines have this plating as far as I know, hopefully someone can chime about the E63.

In short, refuel at a reputable fuel station with a high octaine fuel

I think that this explains, I am the forth owner, always used 99OCT fuel, but the 90k miles done by the other owners could have been a mixture of cheap supermarket fuels. This may have caused damge and explains why I need to top up at least 1lt of oil ...........less than every 1000miles

MarcusF

All factory M112 & M113 (320/430/500/55) engines have Alusil sleeves. This is in the MB press releases as far back as 2001 (probably older, but I thew the old stuff out ages ago). The M156 (63) uses TWAS. Neither of which is Nikasil.

When Mahle builds a Nikasil coated sleeve, they dip an aluminum sleeve in an electrolytic bath of nickel, silicon and other metals for about an hour. The electrolytic reaction causes a silicon-nickel coating to adhere to the aluminum surfaces.

When Mahle makes an Alusil sleeve, a high-silicon content aluminum alloy sleeve is dipped in an acidic bath. The acidic bath etches away the aluminum on the outer surface, exposing a very hard, very long-wearing, silicon surface.

Mahle is the supplier of Mercedes-Benz sleeves.

citylightva

I know the 6.3 is LDS and Twin Wire Arc Sprayed coated. I also know I have no f'in clue what they are talking about, except that I understand the twin wire spray coating....

220S

I just now read an AMG tech bulletin on the M156 and they say the "cylinder walls use the revolutionary LDS coating." Is TWAS the process or also the name of the coating? Hopefully LDS isn't discovered to be susceptible to other issues down the road, LOL.

fwiw, here's a overview on Alusil, Lokasil, and Nikasil. The guy is a well respected manufacturer of cylinders for Porsches.

http://www.lnengineering.com/whynickies.html

Here's part of it:

I've heard of problems with Nikasil™ and high sulfur fuels in the US.
Refining the Alusil™ process is a major focus of automotive engineering today due to the price and complexity of Nikasil™ plating, hence the proliferation of Lokasil™ or similar high-silicon etched aluminum blocks used by many manufacturers . Some attempts to modify the tried and true, yet expensive, Nikasil™ process resulted in chemical incompatibility with high-sulfur fuels. It seems that there simply is no way to make it cheaper without compromising quality and durability. BMW had problems with their 8 and 10-cylinder aluminum Nikasil™ blocks as did Jaguar in the US where the fuel has a high sulfur content, whereas Porsche had zero problems in the 2+ decades Nikasil™ was used. Many also neglect the fact that BMW also uses Nikasil™ in their motorcycles, to this day, without fail. Peeling coatings can be caused by many factors including improper prep or poor plating response of the aluminum alloy used. When the coating is applied properly the nickel will bond stronger to the aluminum than the aluminum bonds to itself or about 25,000 psi. In other words, the coating has higher tensile strength than the aluminum does. Because of this bond, when seizure occurs and plating comes off, there is often aluminum that comes off with it. Coatings will most often peel as a result of substandard materials being used, or when a processing error occurs. The best solution is to use the best materials possible and to monitor the plating process very closely and to have good quality control checks.

I had a few Porches with Mahle Nikasil cylinders. One went to 138k before I sold it. Maybe guy from LN Engineering has a point, that the way it's coated is the real culprit

Apparently all fuel is low sulfur now and so it's not an issue anymore (?) Since 2004, in the US, the EPA has set in place the Tier 2 Vehicle and Gasoline Sulfur program for low sulfur fuel.

"Today’s gasolines do not contain high enough levels of sulfur to cause any problems with these coatings, so that chapter is ancient history. Even so, nickel silicone carbide coatings can be damaged by nitrous oxide or racing fuels that contain nitro methane. The ingredients in these fuels can react with moisture to form nitric acid, which will strip the coating right off the surface. If the application is a performance engine used in drag racing, washing down the cylinder walls after a run with gasoline can minimize any adverse effects if the engine is nitrous boosted or runs on nitro methane. Otherwise, nickel silicon carbide coatings are not affected by pump gas, alcohol or dry fuels such as propane or compressed natural gas."

Good article here:
http://www.enginebuildermag.com/Arti..._coatings.aspx

MarcusF

According to the 63 press kit, the M156 is world's first production engine to feature cylinder bores with twin-wire-arc-spray (TWAS). As you said, it is both the process and the coating. TWAS is a process that creates a very low friction surface, which is twice as hard as conventional steel. The application involves using water at high pressure to roughen the cylinder walls. Afterwards, high voltage is run through two metal wires, which begin to melt. An atomized gas is then used to spray the metal particles from the meted wires on to the cylinder walls. Afterwards, the cylinders are honed.

I have no personal experience with TWAS. I just read the factory press clips.