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fuel coolant reservoir question

25K views 6 replies 6 participants last post by  rod.10853 
#1 ·
bought my truck last friday april 17th....an 08 f 250....started the learning process of whats under the hood..on the fuel cooler,is the system under pressure? i couldn't tell by looking into the peep hole if the quantity was there so unscrewed the cap and had coolant run out of the overflow..so was just curious about this...maybe just overfull ?? or is there pressure in there ???
 
#3 ·
the fuel cooler uses coolant to cool the fuel before it goes back to the tank. It should be pressureised by the cooling system... I think.
 
#4 ·
well....if you look at the capacities in the book it shows the engine coolant at 30 quarts and fuel cooler at 2 quarts....2 different systems...not inter connected....the fuel cooler his its own fill cap.
 
#5 ·
I was also looking over mine today (got mine a little over a week ago). The cap on the fuel cooler says it's 20 psi, higher than the 16 psi for the coolant system. I didn't have time to follow the lines but you are correct about the 2 qt. capacity. Seems like there seperate but can't figure out why or how. Need to do more investigation:thumbsup. This new engine is way different from the old 6.0. I thought the 6.0 was tough to work on, Ford didn't leave any room in this one:haha.
 
#6 ·
yea separate and it has a small electric pump, so it will get under pressure. 6.4 uses high pressure fuel not oil like the 7.3 and 6.0s and when it gets up to real high pressure it gets real hot.
 
#7 ·
Yep, it's a separate system. I recently had a whining noise coming from
the pump a few days after having Ford do a bed plate seal oil leak
repair job. I took the truck back to Ford for the whine, and the
mechanic said that it was due to air cavitation in the system that had
formed in the pump. Supposedly there was air working it's way through
the system after the engine had been pulled and flipped and all from
earlier bed plate seal work. Anyway, the mechanic took the truck back
and said he bled out the air and topped off the coolant and the whine
went away.

The whine stayed gone for about three weeks. It came back yesterday.
I took the truck back to Ford and questioned the mechanic more about
the system, and that's when he told me it's completely separate from
the engine cooling system. Also, he said that the fuel coolant reservoir
was low again and there was air in the pump. He said that now he thinks
that the system is loosing coolant from somewhere and sucking air in.
Also, he said the pump was loose and he went ahead and ordered a
new pump to be installed when it gets in stock.

I didn't get a chance to ask him any more questions, but I wish I
could have asked him exactly what he meant by "the pump is loose".
Also, where is the pump exactly? Is it down in front at the bottom
by the radiator? Because that is where it sounds like the whine is coming
from. Would this pump be removed and reinstalled during the bed plate
oil seal leak repair work? Finally, I had to drive the truck for about 100
miles with it whining. Does this mean hot fuel was being sent back to my
tank?
 
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