Special Fuel Filters for Using Biodiesel

One of my readers, Bill, recently asked me a question about a previous article I had written about biodiesel which you can see by clicking here.

Here's Bill's question:

Dear John,

I appreciate your perspective on conversions. My wife's '99 Ram 2500 seems happy, except for the o-ring seal on the fuel filter cartridge, which, over (short~6 months)time will deform sufficiently to cause an internal leak in the housing, creating a fuel pressure loss in the system, which in turn causes a no-start condition.

New filter and (non-deformed) seal solves the problem. Have you encountered a need to install an alternate/"bio-diesel" friendly fuel filter assembly? I intend to contact Wix, who in my experience is an excellent filter manufacturer, regarding this repeated result. I have found their filters to work very well in the vintage racing gasoline engines I prepare.

Answer

Bill, thanks for your note and this great question!

No, I've not heard of a problem specific to a fuel filter. While there may be some suppliers out there saying their filter has been especially designed for biodiesel, I doubt whether there is need for any such filter. A typical engine fuel filter should provide sufficient protection for your engine whether you decide to run your engine with pure diesel fuel, a blend of diesel and biodiesel, or even 100% biodoesel.

As for leakage or broken seals in fuel filters themselves, from what I understand some car components manufacturers still use the old semi-natural black rubber chemistry in some fuel hoses, o-rings, and other seals. My suggestion is to contact some filter manufacturers and ask them whether the "rubber" components are actually rubber, a blend of rubber and something else, or pure nitrile. Pure nitrile (synthetic rubber) − the stuff from which rubber medical operation gloves are made − are the best bet. They are pretty impervious to most industrial common chemicals, and diesel fuel should be no problem for them. They don't need to be specially manufactured because most companies use nitrile components.

You're right, Wix is a great company. If you speak with them, there is a chance they may not let you buy directly from them, because you are not a bulk retailer. One of their retail outlets is a company called "Amsoil", and you can view their company info by clicking here.

When calling Amsoil, ask to speak with their technical service department and tell them the problems you're having. Make certain to ask them whether the "rubber" components are made or nitrile or some similar derivative. If you decide to buy Wix products from Amsoil, they will ask you for a "ZO" number - and you can give them my number, which is: 1275984

When folks speak of problems they are having with the cars, there are times when what they think is the problem is not actually the problem. Based upon the symptoms you're relaying to me, here are what might be some other problem sources:

Dirty Fuel

Depending on from whom you're buying the fuel − especially the cheap fuel stations − you may be getting dirty fuel, which in turn may clog the fuel filter. A dirty filter may cause the no-start situation you mention. Depending on how your truck's fuel system is designed and how it's supposed to interact with the fuel filter, with a partially or fully clogged fuel filter sometimes the fuel is sent directly back to the fuel tank with little to no fuel reaching the fuel distribution / discharge pump. Because your truck sounds like a newer one, what I'm about to mention here now probably won't apply to you: If excess fuel under pressure isn't sent back to the tank, chances are that fuel under pressure may break a seal and end up spraying around under the hood, or may cause a hose to break somewhere away from the engine. In this case, you would be changing out not only a fuel filter, but other components, too.

Water in the Fuel

Again the cheaper fuel stations may sell fuel that will have some water content. Because water is heavier than fuel, it will accumulate at the bottom of the filter and slowly rise upwards in the filter as more builds up. Over time, the water may fill up most your filter and finally work its way to the very top where the fuel pickup going to the engine is located. Depending on how much water has accumulated in the fuel filter, your fuel system may be sucking up a load of water.

In cases where water has built up so much, again you may have a "no-start" situation, or a successful startup followed by a progressive loss of power accompanied by a lot of "hiccups" in power while you drive along. In freezing weather, your engine may not start at all because the water content in the fuel filter may be frozen, and thus deny the passage of any fuel.

Most fuel filters have a drain port at the bottom that allow you to drain out water in the system. Make certain you open this drain plug every few thousand miles and let some fluid come out. See the accompanying picture of my diesel Jetta's fuel filter with an arrow at the plastic drain plug at the bottom of the filter. Every few months I open that sucker up and let half the filter's fluid drain out. Again, see the picture for the drain spot.

Dual-Stage Fuel Pumps

I've got a friend whose truck has two fuel pumps. One at the tank, and the other under the hood which sends fuel directly to the engine under higher pressure. When the tank pump went out on my friend's truck, he was still able to drive, but got much less power from the engine as a result of this. You may want to check whether your truck has this kind of fuel delivery setup − and if so − check whether both pumps are working properly.

While this isn't the full list of causes for the problems you're having, it sounds like you may be off to a good start in identifying your problem. Thanks again for the note. Good luck in finding the cause, and...

Safe driving!

- John

Sources / Suggested Other Reading:

John's other articles on biodiesel