BIODIESEL IN THE COLD?

Be mindful of these three issues on your diesel before cold weather strikes and you’ll eliminate common diesel cold weather starting problems and at the same time help your diesel provide you with safe, reliable travels throughout the most challenging season of the year.

The Fuel Itself

Cold weather starting problems, sluggish diesel fuel, the necessity to use anti-gel additives . . . You’ve probably heard that the biggest problem with running diesels in cold weather is the tendency of the fuel to gel. No. 2 diesel (the grade recommended for most passenger vehicles) contains some naturally occurring paraffin (wax) and as the temperature drops, this paraffin crystallizes and affects the fluidity of the fuel and may cause hard starting and eventually lead to filter plugging. Unfortunately, this problem is exacerbated when biodiesel enters the equation—biodiesel tends to gel at a slightly higher temperature than diesel.

Luckily these problems are fairly easily solved. Regular diesel fuel is “winterized” or seasonally adjusted at the distributor before it’s delivered to the pumps. Winterizing is done by mixing pump No. 2 diesel with No. 1 diesel, its more refined cousin. Winterizing diesel fuel is done to maintain the cold weather flow characteristics, and the ratios vary depending upon regional distribution. To effectively use biodiesel in cold climates, it must be mixed with winterized diesel in varying percentages, which, once again, are regionally dependent.

Tip: It's a good idea to add diesel fuel cold-weather treatment or an anti-gel additive to ensure that you maintain the low temperature flow characteristics of the fuel. Available at auto parts stores and department stores, anti-gel treatment may be conveniently kept in your trunk and poured directly into your diesel's fuel tank before filling up.

There is ongoing experimentation and research on the cold-weather treatments for biodiesel blends higher than B20.

Are Your Glow Plugs Happy?

If your vehicle is equipped with glow plugs, they need to be in good working condition, along with the glow plug relay. Glow plugs are small electric heating elements (they look like mini spark plugs that are installed in each cylinder.) They are on a timed circuit and activate for a few seconds just before the engine is started. The colder it gets, the longer those glow plugs need to stay on to pre-heat the combustion chamber for a smooth start.

Tip: If your glow plug light on the dashboard doesn’t light when the ignition is switched on, that’s an indication that you may have a glow plug out—and a noticeable engine stumble will be another big indicator. Even one glow plug out may prevent the vehicle from starting.

Check that Battery

When it’s cold outside, everything is a little more sluggish—the fuel is cold, the engine oil is thick and even your car’s cranky. Will she start? Make sure the battery is in good condition. It needs to hold a good charge to provide adequate cranking amps—a diesel requires upwards of 1,000 cold cranking amps to get that engine running. A stout battery provides the sustained cranking power and duration needed to get the engine running in cold weather.

Tip: Check the label on the battery to see how old it is. Those pop-out dots should indicate the month and year it was installed. The label should indicate the life expectancy; they usually range from 48-72 months. If you suspect your battery is getting near the end of its life cycle, it may be a good idea to replace it before cold weather strikes.

For biodiesel cold weather issues, check out winter Rx for biodiesel, along with several quick fixes to get back on the road again.

Whatever scheme you decide on, be certain to do your own freezer testing to find out how your blend works. You should measure cloud temp (the temp at which the biodiesel starts to get wispy cloudy stuff (wax crystals coming out of solution)) and gel temp, the temp at which the biodiesel no longer behaves as a liquid when you tilt your container on its side. You can drive, for a time, with cloudy fuel. But eventually the wax crystals will plug your fuel filter and you will be walking. Once the fuel gels, you are totally beat. Cloud temp is usually just a couple of degrees above gel temp.

Oh yeah, and if your fuel clouds at 30F overnight, you might discover that it clouds at 37 F if you chill it/check it for a few days. Same with gel temps. An "overnight" reading of 17°F is no guarantee that it won't gel at 8 or 10 degrees (F) higher if you chill it for a week. Did I mention that this is a black art?

Here's what I do, which is a combination of blending with K-1, additives and cold processing to take the high temp waxes out.

1: Mix your washed/dried Biodiesel with some percentage of kerosene. I typically add enough kerosene to make true B-66. Do the mixing warm if at all possible and mix it well. By warm, I mean more than 60F.

2. Add 2x the recommended amount of Power Service DFS (Diesel Fuel Supplement) cetane improver. This comes in a white bottle and is available at most Wal-Marts and just about any truck stop. Mix well. Some sources say this step must be done at warm temperatures (like around 60F) to be maximally effective.

3. Cold processing. That's where you "refrigerate" your mix for a few days (which in my case usually means leaving it outside for a few days) and then siphoning out the liquid portion the next day and leaving the crystallized sludge portion for summer use. If I don't get 3 days of good cold weather, I throw a couple of cubies in the freezer for 24 hours. A longer chill period is much more effective than a short one. It's amazing how much more junk precipitates after a full day in the freezer compared with just overnight. Then I let it warm up a bit to clarify the liquid fuel and really settle the waxes. This improves yields a little. Make sure you do this so you can go right to the siphoning step without disturbing the jug. Siphon the clear stuff out and you're good to go. The finished product of course is no longer B-66, but something less than that, depending on 27 different things.

I use a siphon with a "J" shaped bend on the end that I made out of 2 copper 90's. It makes it much easier to siphon from the top down and not disturb the waxy sludge on the bottom. The colder you chill the mix, the better the anti-gel performance in cold temps, and the lower your yield. Interestingly, the precipitated sludge has more BTU's per liter, so you may notice slightly reduced performance on the winter blend. The "sludge" makes great summer fuel.

That's it for the fuel. Of course, there are other factors as well:

1. My car always sits in a garage overnight, along with my wife's car. This helps retain heat. Perhaps your car is exposed to the full fury of winter temps overnight.

2. I added a 120V coolant heater to my VW and use it religiously at or below freezing. So my engine does not start off stone cold in the morning. This increases under-hood temperatures and also makes my heater work right away, which is a nice bonus.

3. TDI engines like mine use a continuous fuel loop, so excess fuel (which is hot) gets returned to the tank. If it's cold out, it routes that hot fuel through the fuel filter canister. If your diesel doesn't do that, you could have a problem with wax crystals plugging the filter.

4. I have a Neoteric brand 12V fuel line heater activated by a rocker switch on the dash. This is in the fuel line just prior to the fuel filter.

5. Never fill the tank right full, so if you have a sudden -20F cold snap, you could dump a bunch of kerosene or winterized diesel in there, along with some more anti-gel additive. You'd at least stand a chance then.

6. I keep a quart jar of winter blend fuel outside on the way to the garage. That gives me a visual check of what's going on in the tank.

7. In some previous model years, they had a problematic fuel pickup in the tank that would plug with even trivial amounts of crystallization in the fuel. The newer design eliminates that problem. Who knows what your pickup looks like.

I am thinking about setting up a coolant loop to heat the fuel tank, like the SVO folks do. (I have since discarded this notion, since my formula has been 100% successful the last two winters.) Legal Eagle is seriously considering setting up a two tank system with heated fuel tank, fuel lines and fuel filter. That would be the cat's meow. Ask him about it.

Please note that you should mix your blend for worst case scenario temperatures plus a fudge factor of several degrees. You should not look at the forecast for tomorrow and mix your blend for that exact temperature. Or maybe you like living on the edge???

Here's the charts and links I promised:

Try this newer link (good as of 2/1/07): http://www.duffscience.com/bd_calculators.htm

The following numbers are all based on mixes with biodiesel made from new soy oil. WVO is found to work better for colder Clements

Please note that there is a whole other vibrant informative discussion about winter issues over