Fuel cooler?

[sheepfarmer]

I've been staring at the parts diagram for the 3560 and in the section for the fuel system it shows a "fuel cooler". It looks like a little old fashioned steam radiator, so no doubt that's what it does. Can anyone explain to me why one would need to cool the diesel? We have just spent 3 months hoping it wouldn't get too cold.

At this point the fuel has been sucked from the tank and passed through the water separator by the first fuel pump, passed by a check valve, gone through a "black box" labeled "tank, reserve fuel", gone through the fuel filter, which sends half the fuel to one "supply pump" on the engine (associated with common rail) and half to a second pump "fuel pump". A line from this second "fuel pump" goes to the fuel cooler. It then returns to the little "black box" mentioned above.

I know pictures would help but computer is still out of commision. Diagrams I had were from Messick's if anyone is curious. I don't offhand see what could have happened to the diesel in that part of the circuit that would have heated it up.

Is this part another item that needs to be kept clean?

Thanks for any ideas!

 

[85Hokie]

I get why we need air to be cooled - the cool air is more dense - thus more O2 in the the denser air - but the fuel? I never heard of that. Gasoline can vapor lock if it gets too hot before the carb, but never have heard of cooling the diesel before the injectors.

 

[sheepfarmer]

Yeah it seems to be a far cry from my 8n that just had that one fuel line. I can see if we were dealing with a gas that compression heats it up, but I didn't think that would happen that much with a liquid? Part of the problem is that one can't tell from the parts diagram how something like a pump works, or what that "tank, reserve fuel" thing does. It is too small to hold reserve fuel, but the lines go a bunch of places.

 

[skeets]

I had a cold can on the street rod,, back in the OLD days

 

[Daren Todd]

As diesel fuel heats up, it expands and gets thinner. You lose horsepower the hotter it gets. Coolers used to bring the temps of the fuel back down for optimum and consistent horsepower and engine performance. Realistically though, you wouldn't notice it unless you were working the snot out of it all day long in hot weather.

 

[sheepfarmer]

Thanks Daren, I forget that these tractors might end up in Arizona being worked at 112 F by someone in an airconditioned cab.

 

[Tooljunkie]

Wouldnt it also make fuel detonate early? Just trying to wrap my head around it. Cooling the fuel would lower the flash point. Although a minute amount would make a difference.

 

[skeets]

My understanding is the cold fuel is denser and when shot into the cylinder you get a more efferent explosion on the compression stroke because the fuel is not already vaporized. There for you have more fuel and less air producing more power. Now that maybe wrong but that's how it was explained to me way back when

 

[nickelplated5s]

They are pretty common on newer diesels. Common rail, high PSI and trying to manage emissions. I'd bet yours is a coolant/fuel versus air/fuel setup. It will actually heat up cold fuel to where the system is optimized.

My Stupid Duty has either 7 or 9 radiators, can't remember right now.

 

[coachgeo]

Hot diesel should atomize better thus improve combustion was my understanding, but can see as illuded to above the improved vaporization might cause the fuel to ignite sooner thus cause a timing issue.

Irrelevant to that though is that hot diesel fuel looses some lubricity and in some IP designs; Fuel oil as lube, is the only lube it gets thus hot fuel shortens the life of the Injection pump. (one benefit of Veg. oil based fuels - Biodiesel etc. is even when heated to temps higher than diesel would reach... it is still a better lubricant for the IP.)

Also often fuel is expected to be a factor in providing some cooling to the IP. Thus in combination this may be in part why there is a fuel cooler available for hot temp climates.

Now could it instead be a coolant/fuel heat ex-changer (fuel heater) for winter use and the translation from Japanese to English got lost..... guess that is possible too.

 

[sheepfarmer]

Curioser and curioser nickel, 7-9 of these things on your truck would imply these coolers must do something important. But what do you mean by coolant/fuel versus air/fuel setup? Anyone know of any books or articles that would explain some of this? The diesel engines for dummies doesn't have some of this newer stuff in it.

It seems like the strategy for the common rail is to keep a steady high pressure flow going past the injectors, and the leftover goes around a complicated circuit. But it is hard to tell how the pump just before the cr works. Has more than one input.

 

[coachgeo]

Curioser and curioser nickel, 7-9 of these things on your truck would imply these coolers must do something important. But what do you mean by coolant/fuel versus air/fuel setup? Anyone know of any books or articles that would explain some of this? The diesel engines for dummies doesn't have some of this newer stuff in it.

It seems like the strategy for the common rail is to keep a steady high pressure flow going past the injectors, and the leftover goes around a complicated circuit. But it is hard to tell how the pump just before the cr works. Has more than one input.

Often the coolant/fuel exchangers are for "heating" fuel. Aka hot engine coolant flows thru a block of metal via passages that lie next to passages that move fuel thru the same block. Heat from the coolant is exchanged too/absorbed by the fuel raising its temperature.

Air/fuel would be designed like a typical engine or oil cooler. A fluid (in this case fuel) moves thru tubes that are cooled by air flowing across the tubes thus lowering the temperature of the fluid

 

[sheepfarmer]

Both of these pumps are located on an extension of the metal block that makes up the crankcase. This extension is about even with the pistons. There would be plenty of opportunity for heat to get transferred. As soon as I have a functional devirused computer again I will put up some pictures. Can't do it with tablet. Thanks everyone!

 

[nickelplated5s]

Been working too much but let's see if I can get them right.
1) primary radiator, air/fluid
2) secondary radiator, air/fluid
3) tranny, air/fluid
4) AC, air/fluid
5) intercooler, air/fluid but most run the compressed charge through air/air
6) EGR cooler, air/fluid
7) fuel, fluid/fluid
8) oil, fluid/fluid
9) ?, I remember an odd number.
It's a T4 motor and designed to run hard. Now my Orange L is an '09 and has 3 cooling systems, hydraulic oil, engine oil and traditional radiator.