Can someone explain what exactly happens when diesel fuel gels up

Only thing I would add is wind chill does not affect truck.

 

Article from agweb.com
Diesel Fuel Gelling
Nov 08, 2018
Gelling of diesel fuel occurs when wax, a normal, necessary component of #2 diesel fuel, crystallizes at low temperatures. The “cloud point” of a particular formulation of diesel fuel is the temperature where crystals of wax begin to form. The “gel point” is the temperature when enough wax crystals develop to transform the fuel from liquid to semi-solid.

Gel point for # 2 diesel varies, but ranges between 10 and 20 degrees F. Wax crystals in chilled diesel fuel measure 50- to 260 microns. That's a definite problem for modern Tier IV Diesel engines that have final fuel filters that filter down to 2 microns.

Cloud and gel points can be lowered well below 0 degrees F. by blending #1 diesel fuel, kerosene or aftermarket anti-gel fuel additives with winter-grade #2 diesel. Cloud point for straight #1 diesel can be as low as -40 degrees F., but using straight #1 diesel is not recommended because of the higher cost-per-gallon and lower lubricity of pure #1 diesel fuel. Adequate fuel lubricity is critical for Tier III and Tier IV Diesel engines.

The best prevention to cold weather problems with diesel-fueled engines is to switch to winter-grade diesel fuel before the first frost, and begin adding anti-gel fuel additives when temperatures fall below 20 degrees F. Home brewing winter-grade diesel fuel by adding #1 diesel fuel or kerosene to winter-grade #2 fuel yourself is an option, but carries expensive risks.

Engineers note that modern Ultra Low Sulfur Diesel (ULSD) #1 diesel fuel and USLD kerosene have less lubricity than old-school #1 diesel fuel or kerosene, increasing the possibility of problems with Tier III and Tier IV diesel engines which are extremely finicky about lubricity. Home-blends of #1 and #2 ULSD fuels may not meet the lubrication needs of fuel injection systems on modern diesel engines. Experts recommend using special aftermarket diesel fuel additives to lower cloud and gel points without reducing the lubricative quality of the fuel.

So, for all you old-timers who used to blend kerosine, or #1 diesel fuel, or even gasoline with the #2 diesel fuel you ran in your old 4020, 706 or 190XT---that strategy could be very, very expensive if you try it with the Tier III or Tier IV Diesel engines in your newer trucks or tractors.

 

And for the record.

Fuel filters WILL be full. They're supposed to be full.

How does one buy #1 to mix with #2 if #1 isn't sold?

There's only 1 pump. Whatever blend is being sold is what you get. And why would you wanna mix a summer blend with winter blend?

 

Some northern fuel stations sell keep at the pumps. Only one I remember is in ND though.

 

Make a note of the mom and pop stops that still have #1 when it’s cold and fuel there. Plenty of places in the colder climates still sell it, just not the big chains.

 

Your fuel filter(s) are where most fuel problem occur. These are an early indicator of

1. The quality of fuel you've take in since last change
2. How long since fuel filter(s) were last changed

So if you're concerned about this recent fueling history or truck maintenance delay, then adding a sufficient quantity of fuel treatment ahead of time is prudent, then run truck a half hour before stopping

 

Great thread. This is something I deal with frequently every winter. In EVERY case it ISN'T gelling fuel that is the issue, it's water separated from the diesel that hits the first of the two fuel filters, freezes, and clogs the pores of the paper.

As you described, there's a loss of power, you might notice you can't get over 1500 rpm's, then it degrades to 1400 rpm's, etc. If it gets really bad you can't even idle your truck.

I get an oil change and PM every 10K miles, especially in the winter. About a month ago I was closing in on that 10K mile mark when I was running in temperatures down to 10°F. Loss of power, etc. I knew the score and limped it to a truck stop with a shop and had them do a full PM. Right as rain after that.

Last week I experienced the same symptoms, strangely at 40°F. I limped to make my delivery and parked at a truck stop. I changed the fuel filter that receives fuel from the tanks (primary or secondary?) and the problem was solved. After further research I found out that water in your fuel can begin closing up the pores in your paper filter above freezing.

I did that last fuel filter change myself. IMHO every driver should have a GOOD filter wrench (NOT the idiocy of aluminum Road Pro wrenches that bend and become useless the first time you try them), a gallon blend of diesel and Antigel, and spare filters. I have clips to secure a large garbage bag under the old filter before I carefully spin it off.

If you know how, open up the old filter after you get it drained. I would bet good money that what you WON'T see is the filter covered in what looks like strawberry sherbert. THAT would be a fuel gelling problem. I would bet that what you WILL see is a blackened paper filter covered in ice. That's the problem. Ice will prevent fuel flowing through that first filter, starving your engine of fuel, and you will likely also have fault codes like "Low Fuel Rail Pressure" coming at you.

ALWAYS carry a set of replacement fuel filters, a blended gallon of diesel, and a good fuel filter wrench. Search YouTube for videos on how to replace a fuel filter, that's how I learned how to do it.

I have replaced that first fuel filter about 2-3 times a winter between PM's. I am considering getting a high end water separator to reduce that hassle.

 

I can't see locals. That would be bad for business. Specially if they got sued for the repair bill.

I saw once. And I think it was ND also.

 

I think the Pilot in Grand Island Nebraska has number 1 diesel

 

Your right. It’s all about the ambient temperature.
I get a laugh when I here people talk about wind chill temperatures.

 

A brisk wind will serve to lower the temperature of the under-hood area [of an off engine] faster (but not more) by pushing residual warm air out and cold air in it’s place. But once at actual air temperature, wind has no affect on engine block temperature one way or the other.