NIKASIL/Sulphur

[Dolmar_Tech_Mgr]

Does anyone have knowledge of chemical reaction problems (other than what BMW, Audi and Jaguar) with NIKASIL cylinders on small two stroke engines and high sulphur fuels that are sold in the US?

Terry

 

[bwalker]

I find that hard to believe since sulphur is found in all gasoline and motor oils. The main anti wear additive(zddp) used in four cycle engine oil has alot of sulfer in it. Diesel fuel has huge amounts of sulphur in it also.

 

[Dolmar_Tech_Mgr]

I too found it very interesting, but BMW seeming to have serious meltdown on cylinder blocks that used NIKASIL cylinders. The problems happened at 30000 miles on cars that had excellent maintanence records. BMW when so far as to stop using NIKASIL in the US engines. They either used ALUSIL or cast iron cylinder sleeves. It shocked me and I have seen some cylinder and piston siezure that just had no explantion. Example at hand I have 5 cylinders from a customer in AZ that has piston scoring on the INTAKE side. The scoring looks just like what you see on a lean seizure on the exhaust side. Oil is present but at this time I dont have the information as to what oil and what ratio.

Terry

 

[Dolmar_Tech_Mgr]

Oh yea, true that all gasoline has sulphur, but not all gasoline has high sulfur content. My brother works for BP and told me that all oil has sulphur, but some oil for different regions have more than others (SOUR CRUDE), Alaska area for instance has very high sulphur and the process to remove the sulphur from the oil is costly. The high sulphur gas is usually purchased from non reptuable Gas Stations, but more convience stores and grocery stores.
Terry

 

[eyolf]

As the oil in the crankcase ages, acid-reaction compounds may become concentrated. Drain oils are considered toxic waste for some reason, LOL!

Anyway, how much effect would there be because those compounds build up and remain in contact for extended periods of time?

 

[tree monkey]

i believe this is caused from the use of ethenal type fuels. washes the oil off the intake side of the piston through the intake port.

later scott

 

[stihltech]

ethanol

Now that the feds mandated ethanol, we maybe seeing this and a few other new problems.

 

[Mack]

Terry,
This sounds like something I've seen on outboards that have run on fuel with "dry gas" in it. or high alcohol content fuel.
The intake side of the piston looks wiped, as does the cylinder wall, the ring(s) look almost like they have rusted??
I would think that the nikasil process would be rather impervious to sulfur, isn't the nikasil a nickel silicon impregnation that bonds to the aluminum at a molecular level as opposed to a plating process?

 

[shooter]

Good point Mack!. NIKASIL is more than a common plating process.

However, BMW had some real warranty problems late 1998-1999, both USA and England. Read about the issues in this link:

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

Sulfur can play havoc with many forms of nickel plating. I have experience with similar problems in the rubber molding industry. Sulfur is a common cure agent for many rubber compounds in the Nitrile (Buna N) family & if a nickel plating is used on the mold cavities, it will begin to flake off within a couple of molding shifts.

But nickel plating has proved to be a very durable coating, especially when used on mold cavities for silicone & other rubber compounds with non-sulfur cure systems.

 

[Dolmar_Tech_Mgr]

I have seen the failures from alcohol and ethanol and those failures were on the transfer port sides with the water forming and the oil being washed out the sides were the first to go and then worked their way around to the exhaust side. I have never seen the intake port get it like this, but I surely am not doubting this. I guess I was really was going out on a limb, but the BMW problem just made me really think. And now I have a headache from such a practice.

Terry

 

[Crofter]

Dolomar Tech.

I'm sure you will be keeping on top of events in this regard. Keep us posted. perhaps there will be a workaround additive or something we can do for our saws. Maybe we will have to learn to make homebrew gas to get some without added ethanol or methanol.

Frank

 

[Mack]

Terry,
Sounds like BMW may have had some troubles with inconsistent combustion temperatures, and maybe a quality issue in manufacture as well. Bad gas is an easy out on a lot of problems, (and often rightfully so).
My understanding is that the sulfur would attack the bond, as opposed to the nickel itself. A simple plating process, which relies on a mechanical bond, that has suffered any wear or damage could allow this to happen. In the mold scenario, the flakes would be an indication of a failure of the bond, not of the nickel. If I understand the nikasil process, it should not peel or flake. At least not without taking a lot of aluminum with it.(Give me a break, it's been over 25 years since I took physical metallurgy!)
What were the jugs off of? I just think that a sulfur problem would be a ways down on the list of suspects. It would be interesting to have a fuel and oil sample to see just what they were running on.
Why don't you bring a BMW to the next service school for us to tear down?

 

[shooter]

Off Topic, but here is a chainsaw metal sign on Ebay for Dolmar fans:


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3658332350&category=10806

 

[Dolmar_Tech_Mgr]

Yea we use to ship those signs from our Sachs-Dolmar warehouse in Shreveport, LA from 1985-1995.

Terry

 

[bandmiller]

we may have to go back to cast iron liners, I would put up with a few more ounces to gain duribility.

 

[Dolmar_Tech_Mgr]

may not have to go backwards at all, but maybe forward with a newer style called ALUSIL - Aluminium and Silcone. BWM is using it now with success against Sulphur.

 

[Dolmar_Tech_Mgr]

Yea, I will just drive my BMW up from Georgia to Maine next time and we can all tear it down and evaluate it put it back together and me be on the way. That is if I wanted to drive that far and mostly if I had a BMW, Just a lowly tech manager, not like I'm a stihl saw salesman making the big bucks.
This website has been a very valuable source of information and there is a wealth of knowledge here and I could not think of a better place to go and ask NIKASIL vs Sulphur who will win?

Terry

 

[ehp]

not sure if this will help but sense i play so much with other types of fuel i have found one thing that happens everytime that i do it
if i mixes even 10% alcohol with high test gas , the normal oil will not mix with the fuel, it seems that the alcohol makes the oil turn to appearance of like it has fish eyes in the mix and if you leave it the mix normally starts to turn white, so with sulfur it could be more a oil thing than sulfur attacking the jug

 

[sedanman]

eph, In this case what do you do to mix oil with high alcohol content gasoline?

 

[bwalker]

Alusil (sp?) is a nickil silcon carbide coating just like Nicisil. I wouldnt be supprised if BMW had a bug in their process and blaimed it on fuel.
Also FWIW sulphur is always reduced during refining as the epa has set very stringent rules on sulphur ppm. All refiners must do this by law.