I wanted to post this for other Rabbits to see. Running 9'of 5/8" heater hose with 3/8"copper inside to the tank in the trunk, gave me very little flow, and heat at idle, so it was changed to 3/4". This is working well now with a reading of 175 deg on the filter housing attached to my outboard motor tank.We bypassed the loop in the tank to maximise flow,so our tank isn't heated for the summer. Vacuum guage at the IP reads 1". Later I am going to put an adjustable flow valve in the 5/8" return, with lines either side of it to heat the tank slightly. The stock heat sensor at the IP inlet, reads one notch down from the engine coolant temp at highway speeds.
The IP return line is flexible 3/8"and goes almost all the way back to the tank to tee into the supply line exiting the filter( for a reheat). The filter/cooler assembly is a John Deere unit from the popular 219 engine. A 5/8"NF thread will allow a stock VW fuel filter to screw on the base of this modified unit. Injector lines are wrapped. Heater hoses pass under the 2 3-way valves and loop around just behind the rad to tie in at one of the cylinder head outlets and the overflow tank. Anyone interested who wants a pic will have to PM me with their E-mail address, I'm no good at posting pictures.

I would like some pics as I am going to convert my rabbit as soon as I get the title issues worked out
fothej@yahoo.com
Thanks

did you use 5/8 tees or 3/4 tees with the 5/8 heater hose?

I used 5/8" tees the first time, which is probably where the problem was.We were running out of time so we focused on making that 9'section the best heat exchanger possible with lots of flow.I'm begining to wonder if I ever have to heat the tank.The IP only has to suck cold WVO through 16"of 3/8"line to the filter. Even when I get WVO from my 300 gal settling tank in the winter,it pours well.

3/8 copper line inside a 5/8 tee is very close.

I'm getting ready to use 3/4 tees with 5/8 hose.

My old Benz I used 3/4 tees & 3/4 hose.

It's only going to flow as well and the smallest/tightest point.

Yep... In my old Jetta, I used 3/8 tube for a fuel line. There was too much vacuum, and it would suck air past fittings. It helped a bit when I looped the return, but it only really worked well once I switched to 1/2 line.

You can check out my 81 Rabbit conversion at www.frytech.blogspot.com . I used 3/4 inch PEX tubing for the coolant lines with 3/8 copper fuel line for my HIH. It has real good flow and heat exchange. You can see the valves I put in to either heat my tank or not depending on the weather.

JimB, very impressive, very nice work, lots of ideas you have given me. The use of ball valves and the homemade heat exchanger with the slide in filter heater are slick. I have a heated 12 liter tank in my Rabbit truck, in the same place as your heat exchanger on your car. My veggie filter is immersed in this tank, inside the coil, and attached to the inspection cover. Everyone's conversion is different, much to be learned.