Alternative Fuel: Waste Vegetable Oil ( Wvo ) Gear Pump

Parts and Tools:
1. SBC oil pump $22 at any parts store. Just ask for the standard pump for an '85 blazer with a 350 engine. You might find a free or cheap used pump at you local engine rebuilder.
2. 45/64" drill bit $25 from McMasterCarr # 29415A34
3. 1/2" NPT tap $17 from McMasterCarr # 2525A115
4. 1/2" drill bit from the home store
5. 1/2" freeze plugs (need 2) from the parts store
6. 1/2" NPT nipples from the home store
7. A small punch from the home store
8. Quality thread sealer from the home store or plumbing supply. Don't buy the cheapest one you can find. These pumps can put out some serious pressure.

You'll also need a drill, hammer and pliers. You might find better prices if you shop around. The flee market is a good place to find the tap and drill bits.

Remove the four screws and take the gears out of the body. Secure the small half of the pump body in a vise. Use the punch to drive the 1/8 inch pin out of the bypass port. There is a spring behind the pin that will come out when the pin is removed. Keep the pin and throw out the spring. Drill out the bypass port with the 1/2" bit. You only need to drill about 3/4" deep. Make sure you bang out the chips after each step or it can jam the gears. Install one of the freeze plugs in the port. Use a bolt or small socket to drive in the plug. You don't need to drill the port if you can find a 3/8" freeze plug. Drive in the plug and reinstall the pin. The plug should not back out, but we have the pin, so put it back.

The stock intake port is also in the small half of the body. It is the 1/2 port oposite of the by-pass post. Drill out the intake port with the 45/64" bit. The depth will depend on your tap. I have to go about 1" deep. If the hole is not deep enough the tap will bottom out and your pipe will not start. Thread the hole with the 1/2" NPT tap. Put some thread sealant on the pipe nipple and install it in the intake port. You are done with the small half of the body.

Secure the main section of the pump body in the vice. Install the other 1/2" freeze plug into the factory output port. I think it is easier to install from the inside ( see pic ). Make sure you drive the plug straight into the port. If it goes in at an angle it could leak. I like to peen over the output edge of the port to be sure the plug can not be forced out by the pressure of the pump.

Drill and tap a hole on the flat part of the body. It helps to drill a pilot hole with a smaller bit first. Again the depth of the tap depends on the pipe nipple you are using. If you tap too deep, the nipple can hit the gears. If you do not tap deep enough the nipple will be hard start. I suggest you drive the tap in a few turns, remove it and try to dry fit the nipple until it starts. If the nipple threads in too far and hits the gears you can "save it" by cutting a couple threads off of the nipple with a hack saw or grinder.

The wall of the pump is thin. I like to put thread sealant on both sides before I thread in the pipe nipple. Make sure it doesn't cross thread when you start it.

Reinstall the gears. I put the hollow gear dry, but I like to use some grease on the drive gear. The grease helps to keep down the amount of oil that seeps out of the drive shaft.

The thread sealant I like to use is called Blue Block. It's also a gasket maker. It might not be needed, but I like to put a thin coat where the two parts of the body fir together.

Match up the two parts and tighten the screws. Spin the shaft with a screwdriver. Sometimes there is a burr from drilling that will make it tough to turn. A few turns should do it, if it's still tight take it apart and see what's wrong.

These are positive displacement pumps. They will self prime and will continue to build pressure until the motor stalls or you blow a hose. There are more threads making contact on the lower pipe fitting. I like to use the lower pipe for the output if the pump is going to be used to produce some pressure (like pushing through a filter). The pumps are reversible so if it clogs while dumpster diving you can reverse the drill and push the chunks back out.

You can drive the pump with any 1/3hp and larger motor or just use a drill with a 1/2" chuck. I made this coupler by drilling out a 3/8 pipe nipple with a 1/2" bit and using two 1/8" roll pins. The coupler is pinned to the shaft on the motor, but the other pin fits the slot on the pump. That makes it easy to remove the pump for another job. My 18v cordless DeWalt drill will fill a 5gal bucket with wvo in about a minute in the cold of December. It pumps about 25-30gal before the battery dies. Thinner oil will pump faster. 3/4 heater hose can be pushed right over the pipe nipples or you can brass hose barbs instead of pipe fittings. This pump has a fitting that will allow a garden hose to be screwed on to the output of the pump. The intake hose needs to be strong enough not to crush under the suction. It will pump faster if you use larger hoses.