Why does my tractor have a fuel cooler?

[mcfarmall]

Seems like the warmer the fuel is the better off the tractor would be. My M5660 has a fuel cooler, yes a fuel COOLER that sits in front of the radiator. It's actually bigger than the hydraulic oil cooler which is a simple u-shaped piece of steel tubing with fins on it. The hydro cooler is in series with my power steering which is run off the tractor main hydraulic system and shares a common sump.

Additionally, the fuel cooler is on the low pressure side...simple rubber lines and hose clamps. I could understand it on the high pressure side as pressurizing fluids will make them hot.

The fuel cooler is what baffles me. Any input would be enlightening.

 

[MossRoad]

Your fuel heats up as it pressurizes and goes past the engine, then any unused goes back to the tank. Do this for hours and hours and your fuel in the tank can heat up dramatically. So cool it on the way back to the tank.

 

[Industrial Toys]

I was surprised to find that on my Duramax too. Mechanic tells me they use the fuel to cool the injector solenoids. Maybe similar.

 

[TMGT]

These are common rail diesels, the fuel can be pressurized to over 20k psi which builds a lot of heat and is cycled through the system constantly which also builds heat. The fuel tank isn't always capable of dissipating enough of that heat, especially at lower fuel levels.
Overheated fuel can cause a number of problems with pump wear and as IT stated, they use the fuel to help cool the injectors themselves.

 

[RickB]

These are common rail diesels, the fuel can be pressurized to over 20k psi which builds a lot of heat and is cycled through the system constantly which also builds heat. The fuel tank isn't always capable of dissipating enough of that heat, especially at lower fuel levels.
Overheated fuel can cause a number of problems with pump wear and as IT stated, they use the fuel to help cool the injectors themselves.

There's a good, concise answer.

 

[MHarryE]

Cool fuel has more energy density. Check any of the larger farm tractors and you will find fuel cooler along with ATAAC - Air to Air After Cooler. Just like the turbo heats the air when it is compressed, the aftercooler reduces the air temp before it goes into the engine so there is more oxygen to burn. Fuel also needs to be cooled for energy density. The only Kubotas I have lacking fuel coolers are the toys - the RTV and the GR2120.

 

[RickB]

Cool fuel has more energy density. Check any of the larger farm tractors and you will find fuel cooler along with ATAAC - Air to Air After Cooler. Just like the turbo heats the air when it is compressed, the aftercooler reduces the air temp before it goes into the engine so there is more oxygen to burn. Fuel also needs to be cooled for energy density. The only Kubotas I have lacking fuel coolers are the toys - the RTV and the GR2120.

The RTV and GR2120 aren't common rail engines. Fuel coolers in tractors and construction equipment were largely if not totally absent until common rail fuel systems came about. Charge cooling has been in the industry since the early 1970's, beginning with water to air coolers then air to air.

 

[TMGT]

Cool fuel has more energy density. Check any of the larger farm tractors and you will find fuel cooler along with ATAAC - Air to Air After Cooler. Just like the turbo heats the air when it is compressed, the aftercooler reduces the air temp before it goes into the engine so there is more oxygen to burn. Fuel also needs to be cooled for energy density. The only Kubotas I have lacking fuel coolers are the toys - the RTV and the GR2120.

Fuel density in these relatively low HP diesels isn't critical, its about fuel system longevity. Charge coolers are about maintaining power levels for forced induction, especially under heavy loads.

The smaller equipment you mentioned are not common rail and don't require or benefit from a fuel cooler.

 

[RickB]

Charge coolers are also very much about exhaust temperatures (EGT) and related engine component life at a given fuel delivery setting. A DT466 set at 250hp will live a lot longer with an intercooler than without.

 

[TMGT]

Charge coolers are also very much about exhaust temperatures (EGT) and related engine component life at a given fuel delivery setting.

Exactly, they can allow a higher output at lower egt's. Its all about efficiency and its amazing how efficient modern diesels could be (except for the add on emissions systems that require extra fuel to operate.......)