I was changing the oil in the dmax yesterday and decided that I could not figure out what this is. Its in front of the fuel tank underneath the truck. It sure looks like a fuel radiator to me. Surely its not to "cool" the fuel. (Wouldn't that cause a problem in cold weather with fuel gelling? So what is it and what is its purpose?


http://www.dieselplace.com/forum/uploads/andrewfessler/2004-10-05_135114_whatisthis.jpg

Fuel cooler indeed on the return side.





Mac

I noticed mine was full of mud and crap so I used the wash to get rid of most of it. What else can be used to clean?


Ben

I'd like to hear the theory on this fuel cooler too. In cold climates I didn't think this was a real good idea either. Why cool it down more to get closer to the cloud point and then somewhat reheat when it gets to the filter?


I'd like to know the temperature drop across the inlet/outlet and how much it really does cool.

Not only does the Bosch Common Rail system put a lot of "pump heat" into the fuel because of the high compression, but return fuel also cools the injectors and the two FCM electronics packages. This puts a lot of heat into the return fuel. The fuel cooler removes some of this heat before the fuel returns to mix with the "cold" fuel in the tank. It's not 100% efficient, will not cool your static fuel any colder than the exposed tank and as soon as you crank up you start moving heated return fuel through it into the fuel tank. I've been through some pretty cold winter conditions and this is no problem at all even in extremely cold temps. Very hot fuel with no removal of return fuel heat in hot climates CAN be a problem and lead to overheated injectors and electronics packages.

Idle chatter is right, there's a lot of heat in the fuel system after the truck has been running for a while. The cooler can't cool the fuel below ambient temp anyway so it dosen't matter in the winter. If your truck start's in the morning then it will just get warmer from there. The cooler passages are big enuf that fuel won't gel in there like it can in the pleats of the fuel filter.


On my big truck with a CAT engine which uses a return system also, at the end of the day in the summer time you can't even touch the aluminuim fuel saddle tanks with out worrying about getting your hand burn't.http://www.dieselplace.com/forum/smileys/smiley18.gif


Heat is more of a problem with the fuel systems on our truck's and that's the reason for the cooler.


My .02 &nb sp; Diesel DragonEdited by: Diesel Dragon

At 29*F ambient temp fuel can be as hot as 98*F after driving for 45 minutes on the interstate.

I think it also helps to reduce condensation and the resulting water in fuel issues.

Its an auxilary satellite antenna.

Its an auxilary satellite antenna.


No PC its just another place where fuel will be leaking from YOUR truck!http://www.dieselplace.com/forum/smileys/hihi.gif


Ah just kiddin ya.http://www.dieselplace.com/forum/smileys/smiley36.gif


Its for picking up a signal in China.http://www.dieselplace.com/forum/smileys/smiley2.gif


Blake

The fuel cooler is used to keep the return fuel temperatures down to an acceptable level where the cross-linked polyethylene tank will not start to deform around its retaining strapshttp://www.dieselplace.com/forum/smileys/smiley19.gif. The maximum continuous temperature of the return fuel (inside the rail and cooling the EDU) is 226 deg F. This is more than enough to cause deformation of plastic fuel tanks. It is my understanding that for MY05 The General is going to a steel tank and eliminating the fuel cooler as a cost reductionhttp://www.dieselplace.com/forum/smileys/smiley5.gif.


BTW - I have seen the front side of plastic fuel tanks on Case IH MX Magnum tractors sag over 0.5" when going from cold empty tanks to completely full and setting in the sun for 2 hours. It should be noted that these were new tractors and that the tanks will continue to "harden" as they absorb moisture from the air and finish curinghttp://www.dieselplace.com/forum/smileys/smiley32.gif.


Regards,

Well there is one other benefit to trying to cool the fuel going back into the tank. As Amric noted, it helps to reduce water issues due to condensation, but also heat and moisture make a lovely environment for the bacteria that can grow in diesel fuel...http://www.dieselplace.com/forum/smileys/smiley11.gif

ok good information. The reasons make sense to me now. At first though, it seemed rather bazaare to have a fuel cooler. Maybe someday when I get some time, I'll crawl under there and use my infrared temperature gun and see what the temp is.


Thanks all.

It is my understanding that for MY05 The
General is going to a steel tank and eliminating the fuel cooler as a
cost reductionhttp://www.dieselplace.com/forum/smileys/smiley5.gif.



If I understand you correctly.......my '05 should have a steel tank and
no fuel cooler. I'll be crawling under the truck to take a look
and will report my findings but I don't believe they made this change.

I've drove my truck in -44°F ambient temps and had no issues with fuel gelling or fuel related problems due to the cold.

seen snow pack into the cooler and cause the fuel to wax.
restriction. also seen the sock on the fuel tank module plug in cold temps.

GM tech department told me is is installed to avoid heat expansion and get this (so the fuel will not ignite)
As my GM dmax instructor said what idiot at the engineering department felt diesel would ignite from return fuel. its not gas....seen some leak and cause driveability issues.

Lay your hand on the fuel rails when your truck is hot and running.
That is what's returning to your tank. I don't think it's (hot diesel
fuel) a fire hazard but it could be a component failure/performance
issue.

Hmmm, very interesting Goldsburg.


Transfer Flow sure went to a lot of trouble to design their steel tank to wrap around that cooler. If the cooler is really there to protect the plastic tank, Transfer Flow could have instructed for its removeal and then made their tank hold another 5-10 gallons probably??

It is my understanding that for MY05 The
General is going to a steel tank and eliminating the fuel cooler as a
cost reductionhttp://www.dieselplace.com/forum/smileys/smiley5.gif.



If I understand you correctly.......my '05 should have a steel tank and
no fuel cooler. I'll be crawling under the truck to take a look
and will report my findings but I don't believe they made this change.





Update: My '05 has a plastic tank and the fuel cooler

It is my understanding that for MY05 The General is going to a steel tank and eliminating the fuel cooler as a cost reductionhttp://www.dieselplace.com/forum/smileys/smiley5.gif.




If I understand you correctly.......my '05 should have a steel tank and no fuel cooler. I'll be crawling under the truck to take a look and will report my findings but I don't believe they made this change.


Update: My '05 has a plastic tank and the fuel cooler



Okay!!! So maybe it didn't get implemented on the GMT800 (yet)http://www.dieselplace.com/forum/smileys/smiley18.gif. I work with the GMT560 "stuff" in my position (with an OE using the Duramax), and maybe the comment I heard from our Powertrain Engineer was for GMT560 (Medium Duty stuff) only.http://www.dieselplace.com/forum/smileys/smiley24.gif


I guess this will teach a newbie to post "insider" information that is heard from a "close" position to GMPThttp://www.dieselplace.com/forum/smileys/smiley19.gif Just thought that I would pass along the explanation from GMPT that was given to an OE using this stuff...


BTW - I have performed some very interesting cooling, powertrain performance, and other Duramax related tests that have provided me with contradictory evidence to some of the comments I have seen on this Forumhttp://www.dieselplace.com/forum/smileys/hihi.gif


Regards,

Okay!!! So maybe it didn't get implemented on the GMT800 (yet)http://www.dieselplace.com/forum/smileys/smiley18.gif.
I work with the GMT560 "stuff" in my position (with an OE using the
Duramax), and maybe the comment I heard from our Powertrain Engineer
was for GMT560 (Medium Duty stuff) only.http://www.dieselplace.com/forum/smileys/smiley24.gif


I guess this will teach a newbie to post "insider" information that is heard from a "close" position to GMPThttp://www.dieselplace.com/forum/smileys/smiley19.gif Just thought that I would pass along the explanation from GMPT that was given to an OE using this stuff...


BTW - I have performed some very interesting cooling,
powertrain performance, and other Duramax related tests that have
provided me with contradictory evidence to some of the comments I have
seen on this Forumhttp://www.dieselplace.com/forum/smileys/hihi.gif


Regards,



Relax! Nobody was tryin to show you up! You made a
comment that got me to thinking if my truck had it or not. I
didn't know either. Now we both know (as does everyone
else). That's how we all learn.



How'bout sharing some of your "interesting cooling, powertrain
performance and other Duramax related tests that have provided you with
contradictory evidence to some comments you have seen" so we can all
benefit.

Edited by: skoryaro2

You are all wrong.


This is a "muffler bearing" radiator. Keeps them cool.


http://www.dieselplace.com/forum/smileys/smiley36.gifhttp://www.dieselplace.com/forum/smileys/smiley36.gifhttp://www.dieselplace.com/forum/smileys/smiley36.gifhttp://www.dieselplace.com/forum/smileys/smiley36.gifhttp://www.dieselplace.com/forum/smileys/smiley36.gif

Not only does the Bosch Common Rail system put a
lot of "pump heat" into the fuel because of the high compression, but
return fuel also cools the injectors and the two FCM electronics
packages. This puts a lot of heat into the return fuel. The
fuel cooler removes some of this heat before the fuel returns to mix
with the "cold" fuel in the tank. It's not 100% efficient, will
not cool your static fuel any colder than the exposed tank and as soon
as you crank up you start moving heated return fuel through it into the
fuel tank. I've been through some pretty cold winter conditions
and this is no problem at all even in extremely cold temps. Very
hot fuel with no removal of return fuel heat in hot climates CAN be a
problem and lead to overheated injectors and electronics
packages.



Am I missing something?? During the quick peek that I took at the
fuel cooler it looked as though it was an "air cooling" system and not
"water cooled". Which obviously means one would have to be moving
forward for the cooler to begin working. If that's the case, then
does the fuel "overheat" per-se during an extended idle? Or are
fuel temp.'s much lower when idling? Or is the engine fan providing
some risidual air flow??

If you want a little adventure, look under your hood and follow the routing of the fuel system lines. That will shed some light on this disussion for you.


Also, diesels produce a lot less heat when idleing than running down the road so there's not as much heat build up in the fuel or anything else. In fact, there is quite a difference of opinion about how long you ought to leave them idleing since a number of problems can be associated with letting them get "too cold", but that's a whole 'nother thread, or several...http://www.dieselplace.com/forum/smileys/smiley9.gif


edit info:


Do a few searches if you're interested in that topic, it generated quite a bit of discussion around here.Edited by: Zeeb

Am I missing something?? During the quick peek that I took at the fuel cooler it looked as though it was an "air cooling" system and not "water cooled". Which obviously means one would have to be moving forward for the cooler to begin working.


Yep, it's an air cooler, and air flow will certainly greatly improve the efficiency, but it will "radiate" convectively with no air flow. I was mostly responding to the concern that it would "freeze" and gell the fuel, but it is in line to only recieve heated returning fuel. The possibility of overheated electronics is the basis for recommendations not to run your fuel tank down too low in hot weather, because you loose the "thermal sump" of a cooler fuel volume in the tank to mix prior to return to the engine. I've only heard of concerns for overheated injectors and FCMs, have heard of no confirmed failures, so I think the system works as designed.