Alternative Energy: How to Make a Heated Waste Vegetable Oil WVO Straight Vegetable Oil SVO Fuel Tank

Parts:
1. Sprayer tank from Northern Tool, Tractor Supply etc.
2. Heat exchanger coil I was getting them here, but they no longer list 5/8"
http://www.aquaticeco.com/subcategories/696/Sweetwater-Heat-Exchangers/heat%20exchanger/0 I will update if I can find a new source.
You can also make a coil from 3/8" or 1/2" bendable tubing. Some people use a stainless steel flexible dryer gas line. One of the best things to use is a few feet of PEX tubing from the plumbing supply. It comes in different sizes and works with compression fittings.
3. 5/8" compression to 1/2"NPT fitting (need 2) from the home store
4. 5/8" compression to 1/2"NPT 90 degree fitting (need 2) from the home store
5. Hose barb (need 2) 1/2 female NPT to whatever size hose you are using
6. 1/2 conduit nuts (need 6) from the electrical section at the home store
7. 3/8" compression to 1/2" NPT fitting from the home store
8. Small piece of 3/8 aluminum tube. Steel or copper will also work
9. 5/8" drill bit
10. 3/8" drill bit
11. 3/4" drill bit or step bit.

This technique can be used on any tank that you can get your hand inside. I installed one of these coils into the stock front tank of my '89 F250. I removed the stock sending unit to get inside the tank. I adjusted the coil to fit through the hole and positioned it near the stock pick up tube. If you can not get into the tank, you can cut an access hole at the highest point on the tank. Make a sheet metal patch and secure it with a gasket and sealant. You don't need to heat the whole tank. You just need to warm enough WVO to feed the engine.

The two 5/8" compression to 1/2"NPT straight fittings need to be drilled out so the coil can pass through them. You could use file if you don't have a 5/8" drill bit. I secure them in a vice because the bit will catch and jam while you are drilling. You may need to wobble the bit and bore the fitting a little more to get it to slide over the coil. Drill out the 3/8" compression fitting with the 3/8" drill bit. The piece of 3/8" tube needs to slip through it.

Find a convenient area on the tank to locate the fittings. My tank was from Northern Tool and has a nice flat spot near the fill hole. Drill three 3/4" holes. You can use a cheap paddle bit made for wood. Two holes are for the coil and the third hole is for the pick up tube. Locate the pick up tube so it will fall into the center of the coil. I have a 1/2" NPT tap so I used it to thread the holes. You can just force the fittings into the plastic. They will cut their own threads. Clean the plastic burrs from the inside and outside of the holes. A knife or file work well. Thread a 1/2" conduit nut on to the 1/2" NPT side of each compression fitting and tighten them down. Some people use washers or Orings to seal the fittings to the tank. I like to use Blue Block gasket maker. RTV or 100% silicone caulk will also work. Apply plenty of sealant to the 1/2" threads and screw the fittings into the tank. Be sure that they go in straight. When it starts to cross thread, stop and start over. I turn the fitting one rotation, stop and look at it from the side to be see if it is getting crooked. Screw it down, but don't over tighten and strip the threads. Apply plenty of sealant to another 1/2" conduit nut and tighten it to the fitting from the inside. Use a wrench to hold back the fitting from the outside as you tighten it from the inside to prevent damaging the threads. Install the other 2 fittings.

Adjust the coil so it will fit into the tank and sit just above the bottom of the tank. I like it to be about 1/2" up from the bottom. Put the coil in the tank and slip the ends through the compression fittings. Adjust the height of the tube sticking above the fittings. Dry fit the 90 degree fittings to the tube to make sure the tube is high enough to fit completely into the 90 degree fittings. I like to leave about 1/4" of tube between the fittings. Tighten the compression nuts to the straight fittings. Use a hold back wrench to prevent the fittings from turning in the tank. No need to over do it. If it drips you can always snug it later. Double check the clearance from the coil to the bottom of the tank once both fittings are tight. Slip the pick up tube into the 3/8" fitting. Adjust it to sit about 1/2" from the bottom of the tank and tighten the compression nut. I do not want the metal to be able to rub and wear through the bottom of the tank.

If your coolant hose matches the size of the coil you can push it right onto the coil without installing hose barbs, but be careful not to crush the tube by over tightening the hose clamps. Depending on the application you may want straight or 90 degree fittings on your hose barbs. I used 90 degree fittings because it matched how my heated fuel line met up with the tank.

I like these tanks because yo do not need a sending unit. WVO can cause a sending unit to gum up and fail. You can see through these tank, so I just pop the trunk every couple days to check the amount of fuel. It is easy to drain and clean the tank if you get some bad fuel. The opening is big enough to reach in with a rag. You could fill the tank with plastic golf balls or wiffle balls if you want to have a baffle. I drove the car hard with only a couple inches of WVO in the tank. It never sucked in any air so I di not install a baffle.