BMW Nickasil

[jackflash]

Most of us know that our cylinder bores are lined with Nickasil. It wears well but is some of the cause of oil useage until a relatively long break in occurs.

 

That said, I have always wondered what went wrong with, I forget what model years, the 540M BMW car engines that were produced. BMW replaced a large number of these V8's with Nicasil cylinders after they ran fine then suddenly began using excessive oil before 100K miles. Nickasil was not used anymore in their cars after that costly snafu.

 

I used to own an M Roadster and it was one fine running automobile but had the straight six and gobs of HP.

 

Anyone know what caused the Nickasil failures in the 540M's?

[PLW]

I believe the problem with Nickasil had something to do with the operating temperature of the cylinder and a chemical reaction between the combustion event and the cylinder. Air or oil cooled engines run at higher temps as opposed to water cooled engines so this was not a problem in the past. BMW had used the Nickasil cylinders for years on the airhead motors as did Porsche so no one foresaw a problem. BMW switched to aluminum-silicon for the car engines to solve the wear problem. The original "fix" for the Nicksil motors was an ECU reflash and a higher temp thermostat, which worked to some degree, but the real fix was a switch to aluminum-silicon.

[James Clark]

http://www.bmwworld.com/engines/nikasil.htm

[smiller]

Interesting article, and it leads to the question... is this still a potential issue for Nikasil cylinders or is the sulfur content of current fuels low enough to prevent the problem, or perhaps with some experience under their belt BMW changed the Nikasil formulation in a way to make the problem less likely? After all BMW motorcycles w/Nikasil do not seem to show any tendency towards abnormally high cylinder wear (meaning beyond manufacturing defects), in fact quite the opposite as far as I'm aware.

[Blue Beemer Dude]

I had one of those nakasil engined Bimmers, and had the engine replaced after the EPROM flash (on BMW's dime). The car never ran right after the EPROM flash either and they ended up buying it back. Long story. I recently discovered that Jaguar had the same problem with their engines in the 97-99 time frame.

 

My understanding of the issue is that it is the North American gas formulation that caused the problem, with its higher sulfur content than European gasoline. I don't think this has changed.

 

Michael

[James Clark]

Here's another FAQ.

 

http://www.e34v8.co.uk/nikasil.htm

[RFW]

Air or oil cooled engines run at higher temps as opposed to water cooled engines so this was not a problem in the past.

 

This doesn't explain the fact that the K100 in all its years of production had nikasil plating and has an outstanding reliability record, yet is water cooled.

 

As I understand it, there are several different process that are similar to Nikasil that were used. Some work better than others.

 

It is also worth remembering that the old Chevy Vega used "Aluminum-Silicon" technology and was a well-known oil burner.

 

Bob.

[RFW]

perhaps with some experience under their belt BMW changed the Nikasil formulation in a way to make the problem less likely?

 

Changing the "formulation" won't help. The problem is acidic sulphur byproducts of sulphur combustion corrode nickel. And it is the nickel matrix that holds the silicon carbide wear-resistant particles in place.

 

Bob.

[smiller]

Here's another FAQ.

 

http://www.e34v8.co.uk/nikasil.htm

Got to love this quote: "Secondly, and equally worryingly, BMW appear to be reluctant even to test engines, but will do it if you insist and pay them to do it. BMW dealers must have hundreds of problem cars going through their workshops every year which the mechanics know about but which they ignore completely. They appear to wait until the problem gets so severe the owner stumbles across the problem himself."

 

Sounds kind of familiar somehow.

[jackflash]

Here's another FAQ.

 

http://www.e34v8.co.uk/nikasil.htm

Got to love this quote: "Secondly, and equally worryingly, BMW appear to be reluctant even to test engines, but will do it if you insist and pay them to do it. BMW dealers must have hundreds of problem cars going through their workshops every year which the mechanics know about but which they ignore completely. They appear to wait until the problem gets so severe the owner stumbles across the problem himself."

 

Sounds kind of familiar somehow.

 

I wish I didn't agree with your statement but it seems to be true

[Thatman]

You guys do realize that every Honda motorcycle motor is Nickasil plated. That isn't why the BMW's take a long time to break in. I don't know what it is..but that ain't it.

[jackflash]

You guys do realize that every Honda motorcycle motor is Nickasil plated. That isn't why the BMW's take a long time to break in. I don't know what it is..but that ain't it.

 

Nope. Didn't know that. Good question then, why do BMW's take so long to break in?

[BUSTED]

BMW has been using nickle-silicon coated cylinders on the twins for at least 25 years. I've never had an oil usage problem. Even the 96RT that I changed to Mobil 1 at 965 miles,(78,000miles in 29 months), I never added oil between changes after the first service. I changed my current RT to Mobil 1 at first service and it doesn't use oil either.

[bmwmick]

BMW has been using nickle-silicon coated cylinders on the twins for at least 25 years. I've never had an oil usage problem. Even the 96RT that I changed to Mobil 1 at 965 miles,(78,000miles in 29 months), I never added oil between changes after the first service. I changed my current RT to Mobil 1 at first service and it doesn't use oil either.

 

Like Busted,

I changed to Mobil 1 at the second oil change. Never had an oil consumption problem.

Odd that BMW mandates the Police Motors MUST use BMW Synthetic from the 600 mile mark on.........

 

 

Mick

[RFW]

BMW has been using nickle-silicon coated cylinders on the twins for at least 25 years. I've never had an oil usage problem. Even the 96RT that I changed to Mobil 1 at 965 miles,(78,000miles in 29 months), I never added oil between changes after the first service. I changed my current RT to Mobil 1 at first service and it doesn't use oil either.

 

It's "Nickel / Silicon CARBIDE", not "nickel silicon". There is a huge difference!

 

Bob.

[smiller]

Changing the "formulation" won't help.

 

This doesn't explain the fact that the K100 in all its years of production had nikasil plating and has an outstanding reliability record, yet is water cooled.

 

It's "Nickel / Silicon CARBIDE", not "nickel silicon". There is a huge difference!

 

Bob, you seem to have a lot of subject matter expertise here. If none of the above factors apply then what do you think might account for the long life of Nikasil bores in BMW motorcycle applications?

[BUSTED]

I was wondering if you could post your source about the carbide reference. I've seemed to miss it in the BMW materials I have. They do refer to the coating in one BMW publication as, "Gilnisil, an ultra-strong nickel-silicon alloy combining minimal frictional loss, superior stability at high speeds, and a long-running life to reduce oil consumption to a minimum."

[RFW]

Bob, you seem to have a lot of subject matter expertise here. If none of the above factors apply then what do you think might account for the long life of Nikasil bores in BMW motorcycle applications?

 

Well, I really don't claim any specific expertise here, outside of a reasonable understanding of the basic metallurgy and chemistry issues.

 

The evidence seems clear that the basic problem is the result of the combustion products of sulphur in the fuel. The SO2 and SO3 produced result in Sulphurous and Sulphuric Acids (respectively) when combined with water (also produced by the combustion process). Most probably aided by a strong high temperature oxidizing envonment, this corrodes the Nikasil's nickel matrix. The Silicon Carbide component of Nikasil would not be directly attacked, but since it only amounts to about 4% of the total, once the nickel starts disappearing, the hard carbide particles just crumble away.

 

That much is pretty clear, but the problem is, as you have stated, why do bikes bave no problem and many cars do? The other puzzling thing is that nickel is well known to be very resistant to acidic corrosion! At least it is in a normal benign (non-oxidizing( environment. Clearly, this is a more complex problem than just simple acidic combustion byproducts causing corrosion.

 

Temperature is claimed to influence the problem, as evidenced by BMW's recalibrating the fuel injection of some affected cars for higher combustion temperature. Bikes, with their much lower mass engine blocks and much lower volume cooling systems, come up to temperature much, much faster than a big car motor. So this might be a cause.

 

The fact that some car owners had no problems at all, and others toasted their motors after only 30,000 miles, implies that there must be some connection with the way the car was driven, since in any given area there is no significant difference in suphur content in fuel. I also doubt that there is any significant differences in the Nikasil in one motor to another, since the problem is simply the corrosion of the nickel matrix, and nickel is nickel!

 

So it may be that cars that suffered worse from this problem may have seen a lot of short trips, where the motor spent a higher proportion of its time still "cold". Bikes, with their much lower mass motors and cooling systems, spend very little time "cold".

 

What is also interesting is that before a car or bike with a catalytic converter is warmed up, there are two things that occur that may cause the problem. The first is that the system runs open loop (the O2 sensor is not working when it is cold) and the system is probably running a bit lean (excess oxygen), meaning there is an oxidizing environment. The second thing is that there may be some liquid water droplets available (from combustion) that will allow the formation of acids from the sulphur oxides mentioned above. With a fully warmed up motor, only "superheated" water vapour is available, so it is likely no sulphurous or sulphuric acids can form, and the sulphur oxides simply go out the exhaust as non-corrosive ( albeit smelly) SO2 and SO3. All this also seems to point to problems that could occur before the motor is warmed up.

 

Anyway, that is one possible scenario. I am sure that BMW must have a better handle on it (whether they are saying they do or not).

 

Bob.

[RFW]

I was wondering if you could post your source about the carbide reference. I've seemed to miss it in the BMW materials I have. They do refer to the coating in one BMW publication as, "Gilnisil, an ultra-strong nickel-silicon alloy combining minimal frictional loss, superior stability at high speeds, and a long-running life to reduce oil consumption to a minimum."

 

Gilnisil is not the material in question here. It is (as you say) an alloy. But Nikasil is not an alloy. It is a coating made of pure nickel with 4% of Silicon Carbide particles distributed throughout. It is a MIXTURE of these components; it is not an alloy.

 

The aluminum alloy cylinder bores are plated with a proprietary "Nikasil" plating by the Stuttgart piston and diecasting manufacturer "Mahle Kolbenfabrik". This is basically pure electroplated nickel, with 4% of its volume made up with microscopic particles of Silicon Carbide distributed throughout the nickel matrix (God knows how the hell they do THAT!). As stated earlier, this is NOT an alloy, but a MIXTURE of nickel with SiC particles distributed throughout. Silicon Carbide is the "sand" in "Sandpaper, so as you can imagine, it is extremely hard and wear resistant. The overall thickness of the Nikasil layer is less than 0,1mm (less than 4 thousanths of an inch.

 

As for my source for info on Nikasil, it was something that I learned while working with the company Eberspächer near Stuttgart who is a major supplier of automotive components there. But I believe it is also mentioned in one of the websites others quoted earlier.

 

Bob.

[BUSTED]

The reference above to the Gilnisil coated cylinders in my post is a direct quote from BMW in an oilhead booklet. I have BMW items that go way back and did find reference to "nickel/siliconcarbide coated cylinders" in a 1982 showroom brochure. Imagine that!

[RFW]

The reference above to the Gilnisil coated cylinders in my post is a direct quote from BMW in an oilhead booklet. I have BMW items that go way back and did find reference to "nickel/siliconcarbide coated cylinders" in a 1982 showroom brochure. Imagine that!

 

After a bit of detective work, it turns out that Gilnisil is a proprietary nickel/silicon-carbide codeposition coating that is produced by the Italian company "Gilardoni". According to one obscure BMW link, the "Gil" in Gilnisil comes from the first 3 letters of the company's name.

 

It appeared to be a coating very similar to Nikasil, and is used (among other places) in that absurd looking R1200C BMW Cruiser bike.

 

Since Nikasil is a trademark belonging to Mahle Kolbenfabrik, it appears that Gilnisil is just another company's attempt to duplicate the Nikasil process under a different name.

 

Bob.

[sardineone]

The fact that some car owners had no problems at all, and others toasted their motors after only 30,000 miles, implies that there must be some connection with the way the car was driven, since in any given area there is no significant difference in suphur content in fuel.

I'm going to venture an educated guess on this one. How about oil change intervals . I'd say for the most part bike owners are very fond of their machines and aren't going to stretch an oil change to 6,000 miles just because the maint. schedule says you can. I can imagine some car owners might? So I postulate that cleaner oil from more reasonable oil change intervals might be the difference. Personally if my oil is dirty looking, I change it!

[RFW]

I'm going to venture an educated guess on this one. How about oil change intervals .

I really think that is not an issue. The problem is already attributed to the byproducts of sulphur combustion (in the fuel), that corrode the nickel matrix. Not sure how oil changes would make a difference here. But who knows.

 

Bob.