Looping Fuel Return on a 6.9l IDI?

[mankypro]

One of the things I've been working on is getting my WO fuel temps a little higher (20-30'F), I currently get about 120-140'F from my set up which includes a coolant heated, in tank pickup and a Vegtherm mega in the engine compartment just before the filter.

The folks at Plantdrive are suggesting that I loop my return lines into my supply line and that it would increase my fuel temp by the amount I want by recirculating already heated fuel back to the IP instead of to the WO tank.

Here's my question, should I do this? I've read in a few places that Ford mechanics suggest NOT doing this because it can introduce air into the lines and other bad things.

If I decide to do this I was thinking of adding the T to the WO supply line BEHIND my 6 valve Pollak from my return line.

Any thoughts on this?

Frankly I'm considering just adding another Vegtherm since I have the extra amps to power it. But it's much more expensive than a few brass fittings.

 

[hheynow]

Loop your return. The advantages are numerous. The only problem with air getting into the loop is it has nowhere to vent, but every time I change my VO filter I know I'm introducing some air BUT it starts right up WITHOUT even a hiccup. The fix is putting a three way ball valve where the loop returns to the filter. When you have air (trust me you'll know it) turn the valve to the other position while the truck is running. A mixture of oil + air will spit out. Have a bucket ready. Once you see pure fuel exiting switch the valve back to the looped position. Life is simple!

 

[hheynow]

Frankly I'm considering just adding another Vegtherm since I have the extra amps to power it.

What rated relay are you using for the Vegtherm? The relay should ALWAYS be rated greater than the draw. I'd think twice about using one for both unless yours is rated at 80 amps.

 

[mankypro]

The VegTherm Mega comes with a relay whether or not I want one - I'd most likely just wire the second relay along side the first one since all the wiring is there already.

Where would you suggest I loop the return? You have a PSD so you don't have a 6 port pollak do you?

What rated relay are you using for the Vegtherm? The relay should ALWAYS be rated greater than the draw. I'd think twice about using one for both unless yours is rated at 80 amps.

 

[MIDNIGHT RIDER]

This is sort of a two-edged blade.

The I-pump requires a high volume of fresh COOL fuel cycling through the return system to keep the pump cool, plus the high volume also keeps it lubricated.

Granted, vegetable oil is somewhat slicker than ULSDiesel; but I am curious as to the long term effects of the raised temperatures of the fuel that is supposed to be cooling the pump, plus the decrease in circulation volume that will result from looping the line, UNLESS maybe that line was looped into the draw side of the lift-pump, thus maybe pulling the fuel through at a higher volume.

I don't know; I'm just curious.

 

[mankypro]

Isn't one of the fears of a split shaft the sudden temp change of cold fuel coming in contact with a hot IP? At least that's what I'm reading. In any case I don't switch over until my engine coolant temp is at least 160'F.


For the record I'm currently running WMO not WVO - but will run WVO if I can get my hands on enough of it.

 

[hahn_rossman]

I'd recommend using a coolant heated heat exchanger right before the IP. Most people use a flat plate one. Your WVO temperatures should be at least 160F to keep everything happy. The current thinking on looped returns is they do help, but especially if you have a three way valve plumbed in so that you purge air along with WVO at shutdown.

 

[MIDNIGHT RIDER]

I'd recommend using a coolant heated heat exchanger right before the IP. Most people use a flat plate one. Your WVO temperatures should be at least 160F to keep everything happy. The current thinking on looped returns is they do help, but especially if you have a three way valve plumbed in so that you purge air along with WVO at shutdown.

Instead of dumping in a cup, could not this purge be simply routed through the returns back to the tanks ??

 

[hheynow]

Isn't one of the fears of a split shaft the sudden temp change of cold fuel coming in contact with a hot IP? At least that's what I'm reading. In any case I don't switch over until my engine coolant temp is at least 160'F.

That's the best reason to put the FPHE after the Pollak (which I have) so after you flip back to purge, the fuel is already warm. A slow warm up as you drive and a warm down when you purge. Imagine a Colorado cold snap when you flip from 180*F WMO to 16*F rear fuel. That's an IP heart attack waiting to happen.