Thursday, May 10, 2012

Tangled mess O’wires and a Pollak

I’m working on converting my motor home project to run on waste vegetable oil. Since it’s raining again, I’m test wiring my 6 port Pollak valve inside. Stop snickering, that’s what it’s called. What it does is allow me to switch from one fuel tank (diesel) to the other tank (veggie.)
The idea is that once the engine, and the WVO reach proper temperature, then the engine is switched from diesel to WVO. Before shutting the vehicle down for a long period of time, the switch is thrown back to diesel to wash the veggie out of the engine. That’s a very important step if you want to be able to easily start the vehicle again.

Rather than bolt the valve under the vehicle and then connect all the wires, I wired it up on the kitchen table first. A 12 volt jumper pack suppled the power to run the valve. After wiring it up just like the diagram indicated, the valve did not work. Bummer. At least I discovered this in my kitchen instead of lying on back under the vehicle with rust and dirt falling in my face.

This is where a multi-tester pays for itself. One by one all the wires and the switch were tested for proper continuity. That eliminated any bad wire connections. The switch, however, wasn’t doing what it was supposed to do. Either the switch was defective or the wrong type of switch was shipped. They are cheap enough so I’ll be picking one up at the auto parts store. With any luck they’ll have one that matches the other switches on my dash.

Bypassing the switch and getting power directly from the battery ran the valve just fine. When the valve switches over, it make an audible click. Blowing through the ports confirmed it was switching over.

There has been some negative talk about Pollak valves on the WVO forums. Some say they can’t stand up to the heat from WVO. Since I had 400,000 trouble free miles from my valve on my Mercedes Benz conversion, that wasn’t a concern of mine. Not only that, the manufacturer warns to use a filter so the oil in the valve is clean. My installation had the filters after the valve. Sometimes my fuel, both veggie and diesel, was pretty dirty. All those trouble free miles speak for themselves.

A more valid comment is that the Pollak valve dumps some veggie into the diesel tank when it switches over. While it’s not a problem in the summer, but the added veggie can cause hard starting in the winter. This is true. My easy solution is to run the diesel tank nearly empty and then fill with fresh fuel. My other solution is to drive to Florida in January. That works pretty good too.

I like to keep my veggie diesel conversions as simple as possible. I’m reusing a lot of parts from previous vehicles. It was tempting to reuse the old Pollak valve from my Benz conversion, but after 400,000 miles of service, that could be asking for trouble.

Sadly, the 19 gallon veggie tank that I pulled from my 240D Benz didn’t fit the place where I want to install it in the motorhome. The condition of the tank was also a bit worse for wear. (those same 400,000 miles.)

Fortunately, the 12 gallon tank I had salvaged from my old 300D Benz conversion could be reconditioned and reused. Only had about 100,000 miles on that one. It’s a bit smaller that what I’d like, but it’s free. Carrying a few extra jugs of veggie in the back is no big deal. Later on I could always install a bigger tank.

Well, if only the rain would let up, then I could install a few things.



  1. Interesting. I ran my diesel with a 15-20 percent veg oil mix and lost a lot of power I'm committed to trying again though, sometime soon... guess I could put in another tank and make the required engine modifications easily enough... thanks for posting that...

    1. Lost a very tiny bit of power running wvo in the Benz. The F250 truck didn't lose enough power to notice. You might have had fuel supply problems with the thicker blend, starving the engine.

      It also will plug diesel fuel filters as veg will clean the engine, tank and fuel lines. All that crap has to go somewhere. I keep spares handy. Eventually it settles down.

  2. Good thinking on your part to test everything out before doing a full install!

    Keep us posted on what you find and how it goes, OK?

  3. Smart move putting it together inside first, like you said.
    Pollack electrical parts are common, I always used to go to their website to get the wiring schematics for hooking up trailer wires with the various plugs available for different systems. I had it printed out at one time, note to self, do it again and have it laminated.
    Very handy.

    Best of luck to ya.

  4. I got the switch working today. Then cleaned up my work: wire ties, shrink wrap connectors, in-line fuse.