Here's a new reason for the fuel additives, as it looks like switching betwen LSD, ULSD and BD **may** cause the fuel pump seals to harden and not recover.
From the Berkeley BioFuel Oasis website -
Ultra Low Sulfur Diesel Warning: [back to top] Possible Fuel Pump Failure in VW TDIs, post ‘99 Mercedes SDs, or any diesel with an injector pump lubricated with fuel - We’ve seen a sharp rise in injector pump failures, a previously rare occurrence, since California switched to Ultra Low Sulfur Diesel (ULSD) in October 2006. ULSD is causing problems in all types of diesel engines around the country because of its lack of lubricity and seal-shrinking properties. After surveying our customers and talking to diesel engineers and mechanics we’ve reached the following conclusions:
How could ULSD cause fuel pump failure? Injector pump seals: The original formulation of petroleum diesel caused pump seals to swell, and biodiesel swells seals even more. ULSD causes the seals to shrink and harden. Too many changes can damage the seals and the pump will leak fuel and/or suck in air. Most of the failures due to damaged seals have occurred in cars that have run on all three types of fuel. Three or four fuel changes are simply too many. Injector pump seals that are only exposed to two types of fuel, biodiesel and ULSD, are apparently not failing. It is likely that injector pump seals that have never been exposed to the pre-’06 blend of diesel will be OK.
Mechanical wear: ULSD is very low in lubricity, which is not good for pumps lubricated with fuel. Both biodiesel and ULSD attract water, and water causes rust, which is abrasive.
Recommendations:Cars that have run on pre-’06 diesel:
- Avoid running ULSD after switching to biodiesel. If you cannot get biodiesel when you are on the road, add the ULSD when you’ve still got at least 1/4 tank of biodiesel so that you are running a blend and not making an abrupt switch.
- Use a diesel fuel conditioner, such as Stanadyne, when you do not have access to biodiesel. 3 oz. of conditioner per tank of ULSD will replace the lubricity properties of biodiesel.
- Consider a preemptive injector pump rebuild, especially before a road trip that will take you away from biodiesel sources. A planned repair is a lot less expensive and inconvenient than an unplanned one. The new seals that have never been exposed to pre ‘06 sulfured diesel will theoretically be less likely to fail
Cars that have not run on pre-’06 diesel, or had injector pump rebuilds after October 2006:
- Current evidence shows no problems with switching back and forth between biodiesel and ULSD, but be cautious anyway. Avoid abrupt switches in fuel types whenever possible; blend fuel types between changes. Biodiesel swells seals and ULSD shrinks them, so switching back and forth can theoretically strain seals. ULSD has only been around for a year - It may simply take more time for problems caused by fuel changes to surface.
- Use a fuel conditioner when running ULSD.
All diesels running either biodiesel or ULSD — avoid rust:
- Keep your tank full overnight when the days are warm and the nights are cold. Less air in the tank means less water condensation.
- Use a fuel conditioner.
- Add a water separator to your fuel system .
Don’t get ripped off If your injector pump does fail!
- First, try switching back to biodiesel. Several people have reported that running at least 30% biodiesel re-swells the injector pump seals and stops the leaking. Let the injector pump absorb the biodiesel for 24 hours or more before giving up.
- Avoid the dealer unless you can get the repair done under warranty. VW dealers typically charge $3k to replace your injector pump and fuel injectors and purge your entire fuel system. The same repair done at an independent garage typically costs half or less of what VW charges. Dealers are also notorious for diagnosing all fuel system problems in cars with biodiesel stickers as injector pump failures, and have recommended $3k repairs when they simply failed to bleed the air out of a new fuel filter.
- If something doesn’t feel right always get a second opinion before agreeing to an expensive repair.
Where to go for Injector Pump Rebuild:These business only rebuild pumps and do not work on cars. Have your pump removed and send it to:
- Diesel Fuel Injection Service, 8922 NE Vancouver Way. Portland, OR 97211. (503) 235-1947.
OR
- Diamond Diesel, 2550 East 12th Street, Oakland, CA 94601, (510) 532-8500AND
- Use Viton seals: Viton TDI injector pump o ring seals are available from dieselgeek.com. They also sell the basic Bosh rebuild kit if you want to do the repair yourself.
