Fuel heated through IDI pump return?

[veeman]

As the weather starts getting colder, I'm experimenting with running blends of biodiesel (homebrew) and normal petro diesel.  The overall issue is that B100 (straight bio) tends to gell up in colder weather and very well could cause clogged filters, etc in sub-freezing temps.

Anyway, a friend told me that his 2000 TDI has a recirculation loop in his fuel line that somehow heats the fuel filter as the car warms up.  Sounds like a good idea...

In our IDI cars, we only have a recirc line back to the tank after the pump.  Can anyone tell me how much (if any) fuel is heated in colder weather during its journey from the tank through the filter to the pump, to the injectors and then back to the tank?   You'd think that the hot engine would warm the pump and all components and eventually warm the fuel.

I'm just thinking that perhaps during my 30 mile commute, the engine will help warm the fuel and send it back / mix it in with colder fuel in the tank.    This would help the situation, but I'm not sure if the effect would be significant.

It seems that during normal driving, my 1.6TD will use / recirculate a gallon of fuel back to the tank in around 6-8 miles.  Don't ask me how I know.  That means that fuel is constantly being circulated back to the tank (and refiltered)...

More info / theory here:  

http://www.vwdiesel.net/phpBB/viewtopic.php?t=738

Any thoughts?  I've got some "cold testing" data from my biodiesel and how it reacts in blends if anyone's interested.

[jtanguay]

it does make a huge difference.  the main thing, is that the heated recirculated diesel goes back through the filter (at least on my vehicle it does...)

heating the filter is the best idea.  If you really want to get into it, you can machine three plates of aluminum and have an identical flow pattern machined into the center piece + outer inner pieces.

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kind of like that.  The aluminum will absorb a lot of the heat from the diesel fuel, and transfer it to the cooler diesel going to the motor.

www.powerservice.com makes a really good anti-gel that is compatible with biodiesel  I think that would be a lot easier.

[anarchyx34]

I've seen several IDI's that had this setup. All you need it seems is the correct fuel filter, and the "insert" for the filter.

[burn_your_money]

Couldn't you just take the return line from the pump, extend it, wrap it around the filter a bunch of times, wrap the filter in insulating tape and then hook the return line up to where it normally goes?

[745 turbogreasel]

I've noticed better injectors seem to return a lot less fuel than old ones.  www.greasel.com sells a 12V 'fuel filter heater' AKA battery heating mat that seems pretty nice.
It ties to the filter using bootlace technology.