New Diesel Fuel Harmful to rubber gaskets?

[bear15]

Is the New Diesel Fuel Harmful to rubber gaskets? I spoke with a few Diesel mechanics who are reporting problems with the new Diesel Fuel in VW Diesel engines-- e.g. rubber gaskets & seals in fuel injector pumps degrade especially if the vehicle sits for longer periods of time. This repair is $500 - $600.


Any fuel additive suggestions?

[SVOboy]

They say it shouldn't be an issue for old cars: http://www.clean-diesel.org/vehicle_performance.html

I wonder...

[bear15]

Do you know of any suggestive additives?

Originally Posted by SVOboy

They say it shouldn't be an issue for old cars: http://www.clean-diesel.org/vehicle_performance.html

I wonder...

[omgwtfbyobbq]

I've actually heard the opposite. Diesel used to have additives that made the rubber swell, but the new usld doesn't, so after time those seals contract and the pump leaks. This seems consistent based an a couple bits of info I g00gl3d, but as with anything from the intern3tz, YMMV.

- increasing aromatics content increases swell in fuel system parts. Swelling of Viton and nitrile O-rings was within the appropriate ASTM standards on all commercial fuels tested except the 56 percent aromatics fuel containing 54 percent toluene;
- new and old rubber fuel system parts would not be expected to fail prematurely in fuels with total aromatic content of up to 50, or in 48 percent aromatic fuel containing up to 40 percent toluene, plus xylene;
- the amount of swell depends on the type of elastomer with Viton parts swelling significantly less than nitrile parts which in turn swell less than Neoprene parts;
- of the aromatic compounds tested, toluene causes more swell than xylene and mesitylene respectively;

From the NZ govt.

And from dodgeram dot org.

By definition, aromatic content is characterized by the presence of the benzene family in hydrocarbon compounds that occur naturally in the refining of diesel fuel. In the chemical make up of fuel, the heavier aromatic compounds of toluene, xylene, and naphthalene are also present. Limiting these aromatic compounds has the effect of reducing burning temperature and thus NOx formation.

Meaning that diesel fuel with a reduction in aromatic compounds in order to help out w/ emissions/NOx production, will also result in less swelling from seals exposed to blends that had higher levels of aromatics.

I've heard of painting the outside of the pump around the seal areas w/ xylene, or just replace the seals yourself if you can stand the work, but can't stand the price. There's also someone on ebay who's supposedly resealing pumps for much less than $500. GL!

[SVOboy]

Mehbe the old swelling that was holding the gaskets together is subsiding with the non-detrimental ULSD,

[trebuchet03]

Originally Posted by SVOboy

Mehbe the old swelling that was holding the gaskets together is subsiding with the non-detrimental ULSD,

I wouldn't think that the material would "unswell" -- but then again, I've seen some goofy things Somewhat newer stuff is made from neoprene, very new stuff might be something else... Non neoprene rubber hasn't been used for awhile

[omgwtfbyobbq]

Originally Posted by trebuchet03

I wouldn't think that the material would "unswell" -- but then again, I've seen some goofy things Somewhat newer stuff is made from neoprene, very new stuff might be something else... Non neoprene rubber hasn't been used for awhile

O rly? I have no clue myself since this stuff isn't anywhere close to my major, and even if it was, I probably still wouldn't know. But.......
Wouldn't rubber that swells from exposure to whatever blend of solvents, expand or contract according to the current blend of solvents? It doesn't seem like the solvents bond w/ the rubber, but instead that they fill it, kinda like a sponge... Course I'm a lay person, so I really do have no clue.

There's also posts like this and this.

How Will Diesel Change?

Diesel currently contains up to 3000 parts per million (ppm) of sulphur. The new lower sulphur diesel will contain at the most 600ppm and on average 500ppm of sulphur.

Reducing the sulphur content of diesel can result in changes to several fuel characteristics other than sulphur levels. Many of these characteristics, such as conductivity and lubricity, will be dealt with by the oil industry. This means there will be a smooth transition to the new diesel for most engines.

The desulphurisation process will probably also reduce the level of aromatic compounds in diesel. This reduction in aromatic content could affect some seals.

How Will the Change Affect Seals?

Seals in contact with diesel of high aromatic content often absorb the aromatic compounds, which makes the seals swell. If diesel with a lower aromatic content is then used, the seals may shrink back. The combination of seal shrinking and pre-existing ageing effects such as compression set or twisting can lead to seal failure and leaks.

[trebuchet03]

^^ that's why I wouldn't think it would... For gaskets/seals, a neoprene blend is used to avoid just that... Ideally, you don't want any effusion - but even worse is to revert back. The biggest problem (at least a few years ago - things have likely) with neoprene blends was the elastomer nitrile - which, alone, swells up terribly in oxygenated compounds (like acetone et. al.). From what I have been told, mfrs have been changing their synthetic rubbers to take care of that (the "might be something else"). So for newer designs (as mentioned in the OP), it shouldn't be a problem.... But shouldn't is a pretty big assumption

I really wish I had the resources to keep up to date on this type of thing (rather than a few years behind)... On of my material's professors liked this one statistic: "80% of the steels the auto industry used 5 years ago are now considered obsolete." I don't know if that's true or not - but materials are changing very frequently

[Lug_Nut]

I was warned that switching my used (500 ppm petrodiesel) TDI to B100 biodiesel would cause problems because the seals would, depending on who posted, shrink (or swell) and would create (or stop) leaks. Sorry to report that this hasn't happend to me.
Archival reports were that the switch from 5000 ppm sulfur diesel to 500 ppm diesel had the same warnings back about 20 years ago as with the more recent reduction from 500 to 50 ppm, "The sulfur is a lubricant. It's needed for pump life." Sulfur is also a friction material used in cutting fluids and match heads so who do you believe?
The removal of sulfur, the main difference in the now current 50 ppm fuel from two years ago when 500 was the fuel, may have prompted the addition of other compounds to compensate for any perceived loss of sulfur properties. These addititives, if any, may have an effect on the synthetic "rubber" compounds in the diesel vehicle's fuel system.
B100 biodiesel has no sulfur and no additives. I have no leaks since 2001 except for the self induced ones (forgot to tighten the hose clamps).

[Bill in Houston]

Originally Posted by trebuchet03

One of my material's professors liked this one statistic: "80% of the steels the auto industry used 5 years ago are now considered obsolete."

That statistic is now considered obsolete.

Just kidding. ;-p