ULSD (Oct 2006) and Distributor Pump Seals leaking

[Dorado]

Our NB TDI has been running for 4yrs and 35k miles on B100 and Low Sulfur Diesel, with no leaks at all. I kept a neat engine bay and a good eye for leaks because the original pump leaked and was replaced under warranty at 14k).

Now, over the last month (Sept - Oct 2006), the wife has been letting the tank go quite low and filling up with only BP diesel fuel, which over the last month or so is likely 80-90% ULSD (according to oil industry press). I have topped the tank off with biodiesel and PowerService DFS, but not before it unfortunately (!) has run just on ULSD for a few days and a few hundred miles.

Well, one month has been enough to have the middle seal on the injection pump begin leaking towards the engine side.

So check your injection pumps (2003 and earlier US TDI's), and follow the new hot threads on replacing the seals on these pumps:

http://forums.tdiclub.com/showthread.php?t=146953

 

[Gothmolly]

Might be bad luck - B100 and ULSD should be roughly equally aromatic-free.

 

[Bob_Fout]

Our NB TDI has been running for 4yrs and 35k miles on B100 and Low Sulfur Diesel, with no leaks at all. I kept a neat engine bay and a good eye for leaks because the original pump leaked and was replaced under warranty at 14k).

Now, over the last month (Sept - Oct 2006), the wife has been letting the tank go quite low and filling up with only BP diesel fuel, which over the last month or so is likely 80-90% ULSD (according to oil industry press). I have topped the tank off with biodiesel and PowerService DFS, but not before it unfortunately (!) has run just on ULSD for a few days and a few hundred miles.

Well, one month has been enough to have the middle seal on the injection pump begin leaking towards the engine side.

So check your injection pumps (2003 and earlier US TDI's), and follow the new hot threads on replacing the seals on these pumps:

http://forums.tdiclub.com/showthread.php?t=146953

Did you notice a drop in MPG, physically see the fuel leaking out or smell fuel in the engine bay?

 

[Dorado]

No smell or big performance difference, although I have to admit I haven't been myself the principal user of the car for the last couple of months.

But I just looked around the injection pump with a good flashlight and noticed the middle seal had leaked towards the back of the car, towards the engine. I know it's the 'middle seal' just because of the recent thread here on fixing leaking pumps by replacing the seals.

 

[oilhammer]

Just in the last year, my own '91 Jetta, my friend's '82 Rabbit, my brother's '89 Jetta, and most recently a '97 Passat have all had pump leaks. So it is a good idea for everyone to keep a close eye on them.

 

[Georgeseq]

For some refineries there has been a significant difference in aromatic levels between LS and ULSD, which can cause seal shrinkage and resulting leaks. Some refineries have kept close watch on their ULSD aromatic levels, keeping them at LS levels and no resulting issues with seals.
George Morrison, STLE CLS

 

[Dorado]

A post here on goverment warnings about ULSD, also points to the difference in aromatics:

http://forums.tdiclub.com/showthread.php?t=156285

Fuel System Seal Leaks - Non-nuclear industry operating experience using ULSD shows an increased incidence of fuel system leaks at points where elastomers (O-rings) are used to seal joints, with most leaks occurring at the fuel pump and injectors. The evidence to date suggests the problem is linked to a reduction in the aromatics content of the ULSD which affects seal swelling, as does seal material and age of the material.

 

[Drivbiwire]

Before pointing fingers at 1 month of ULSD consider the quality of your B100, any methanol content in that fuel would destroy the seals.

With that variable thrown into the mix, blaming ULSD is pointless. FYI, ULSD (less than 30ppm per VW) is what these cars are designed to run on in the first place since 1998 and the introduction of the ALH motors and EGR.

DB

 

[oilhammer]

Except that none of the leaky pumps I have come across have had any bio in them at all.

It'll all blow over soon, same as when they added the oxygenates to the gasoline and electric fuel pumps started dropping like flies.

I can say that I have seen more leaky Bosch VE injection pumps in the last 9 months than I have the previous 9 YEARS, so there is certainly something to the ULSD causing leaks. However I think it is simply a case of the fuel switch, not the fuel itself. In other words, if you have a leaking pump, and it is fixed, it is not likely to leak again with the new fuel.

Can't say the same for the crappy gasoline... We got oxygenated gas in the STL area in April of '99. Within 6 months of that, I had replaced more electric fuel pumps on all types of cars (mainly GM, Ford, and Chrysler) than I had in my entire life up until that point. High alcohol content, additives like MTBE and hexane, as well as all the other crap the EPA crams down our throats, really plays havoc on nylon and viton fuel pump internals. But, at least when you're broke down on the side of the road you'll be able to breathe clean air, right?

Luckily the newer fuel pumps are better...for the most part...

 

[McBrew]

any methanol content in that fuel would destroy the seals.

Hopefully, there is no methanol in the biodiesel they are using. Since methanol washes out to easily, I doubt that there is much/any to be found in commercial or washed homebrewed biodiesel.

 

[tditom]

For some refineries there has been a significant difference in aromatic levels between LS and ULSD, which can cause seal shrinkage and resulting leaks. Some refineries have kept close watch on their ULSD aromatic levels, keeping them at LS levels and no resulting issues with seals.
George Morrison, STLE CLS

George- can you give us brand names? TIA

 

[bhtooefr]

Temporary fix from the days of the HSD -> LSD switchover:

Add those aromatics right back in!

 

[oilhammer]

That's fine for the old IDI diesels, but the TDI's tiny injector holes will coke shut.

 

[Dorado]

Before pointing fingers at 1 month of ULSD consider the quality of your B100, any methanol content in that fuel would destroy the seals.

With that variable thrown into the mix, blaming ULSD is pointless. FYI, ULSD (less than 30ppm per VW) is what these cars are designed to run on in the first place since 1998 and the introduction of the ALH motors and EGR.

DB

Valid criticism. But in our case, we have used B100 from only one source for three years and 35k miles, going through many tanks of only B100, and sometimes going 4-6 months on B100 alone. There were never any leaks (and I'm very sure of that). During that time we also had fillups of LSD with low blends of Biodiesel, and that did not cause any leaks.

I think the 'blame' is actually being placed on LSD (well over the 30ppm per VW) that 'swelled' our pump seals to begin with.

The way I look at it, my use of much biodiesel was not enough to prevent swelling of distributor pump seals from the infrequent use of 500 ppm sulfur LSD for 3 years and 35k miles.

 

[Georgeseq]

We went through the same situation with seals when we reduced from High sulfur to low sulfer. Seal shrinkage. It is not the change in sulfur level but simply the aromatic level affecting the seals. We replace the seal with exactly the same seal material which will then take on the new "set" for ULSD aromatic level...
George Morrison, STLE CLS

 

[Grady]

Some info from Cummins re seals and the fuel change.
http://www.blueridgediesel.com/CUMMINS%20TSB_082905%5B1%5D.pdf

And some more . . .
http://www.hoglundbus.com/pdf/IA-0906.pdf