How is this not a shared system other than the cap pressure fritz???

They bleed the same blood but the caps have different blow offs correct?

Denny

 

fuel cooling system is totally seperate from engine cooling system. Seperate tanks, seperate radiators, seperate pumps and no shared lines .

 

 

Great illustration Fritz.

Now it all makes sense! Thanx

 

Great pictures Fritz. Thank you very much. Will be saving those. What brought my question initially was my truck has red elc, and the fuel cooler still looks good. So I need to get that flushed.

 

Awesome pics fritz. Thanks man.

Seth, regarding the red elc...since you don't know when it was installed(or do you?) You could start fresh on that. I use Zerex ELC red. Good for 300,000...and 600k with the extender...though I would never go that long. Combined with a filter(which I still need to get)...you aught to be good for a good while.

 

Previous owner said it is around 40,000 miles old. I have seen the rotella stuff. I am trying to find an elc that is readily available but I haven't found one yet. One where no matter where I am at I can get some.

 

Napa carries the Valvoline ELC (red) that I use. Though I think you may have solved this issue by now.

 

So just to update on what I did on the secondary system. While I was replacing the front cover/oil pump/seals etc, I removed the 2 hoses from the secondary cooler which allowed entire system to drain the green coolant.

Filled back up with distilled water and went to turn on secondary cooling pump to circulate. Found that this was not operating(how long I have no clue). After testing circuit found that the ground was bad somewhere in the loom. I decided to just snip the ground wire and attach new wire and ground to frame bolt which fixed the pump and it started working. Sealed up the wiring connectors with heat shrink and bundled back into loom.

I did have a hard time getting the pump to "prime" as it would not move any water at first. I took off the hose at the upper fuel cooler and filled it, put it back on cooler and used a 5/8" piece of heater hose and pressurized the coolant reservoir by blowing into it and holding, and the pump took a different note and starting circulating that water.

I did this 2 more times to make sure green coolant was gone, then drained completely again by removing hoses etc. Filled back up with coolant same way, and I can now see it circulating in the small reservoir. So success.

I am not sure how long it has been without that pump working, most likely a long time or maybe it was sporadic but now we can hear it when key is on, and it has about a 5 second delay to shutoff once you shut the engine off so you hear it for a short time then also.

Glad we tested the pump first with it out to make sure it pumped, and verified electrical because a new pump is almost $200 from Ford.

Real simple to take pump out with fender liner removed. 2 Hose Clamps, 1-Electrical connector and it pulls out of the rubber grommet that is bolted to the lower shroud. Hope this helps anybody that is having issues with their secondary cooling system and not seeing any flow happening in the small reservoir. Also, it is a 20lb cap which was replaced new also.

 

Great info

can you check the cap spec.

mine had a 20psi cap and when I ordered a new one also got 20psi.


12 psi will lower the boiling point of the coolant some...but more importantly....a lot of coolant could discharge out the drain tube....there’s no recovery tank in this system so eventually significant coolant can be loss.

i made a mini coolant recovery tank using a oem Parts brake bleeder tank which is the size of a small coffee cup. Even at 20psi I get coolant evacuation when hot and then coolant recovery when cold.

just something’s ng to look into.

 

Fritz, You are exactly correct. It is a 20PSI cap. Motorcraft Part# RS-524

 

I used this method today and it worked great. Thank you for the idea. Did take your advise and ran a hose to a bucket to catch what’s being flushed out. What is the capacity of this system? I feel I only flushed at tops a couple quarts. I refilled with final charge to match my cooling system.

 

Dang hard to find specs on the 6.4l secondary cooling system. I did find a thread on another forum that states "Total coolant capacity in the 6.4 is just a touch under 33 qts...YES...over 8 gallons. All but two quarts is for the main cooling system with those two quarts going in the fuel cooler. " Which sounds about right from the amount I was able to put back in.

 

Also just a friendly reminder from my recent hiccups on a road trip that there is a bleeding procedure for the fuel cooling system after you refill. Research it. Will save you a LOT of time and headache.

 

And I understand it also has it's own dedicated pump.