Tuesday 4 July 2006

It all comes together... Conversion complete!

The final stage of the veg-oil conversion of the 300D has been completed! This stage was almost all plumbing work. It now runs on

  • Diesel,
  • any new vegetable oil,
  • any used vegetable oil,
  • biodiesel or
  • any combinations of the above!

The veg fuels are filtered to at least 5 micron before filling the tanks and then again by a pre-filter and an on-board water-removing CAV cartridge type filter.

In operation, I start the car on diesel. It takes 3 minutes for the 3litre Mercedes OM617 diesel motor to heat up the coolant suffiently to enable burning of the cooking oil to commence. I flick the on dash fuel selector switch and about 15 seconds later I’m driving along smelling like a mobile Maccas! When I stop and turn off the engine, if I’m not intending to restart within a couple of hours I’ll shut down on diesel to make starting easier. However, it will start OK on the cooking oil, but to avoid any damage to the injectors, a proper shut-down is preferable. I’m thinking of the possibility of using a turbo-timer to automate the shut-down.

Here are the final shots of the installation:


This one shows the brass tee into the heater circuit to take off coolant for the heat exchanger. I’ve discovered that quality brass fittings are expensive! This tee routs the coolant to the 26 plate heat exchanger, from where it returns it to the cooling system via another tee before the thermostat on the other side of the engine. As you can see, I can still access the oil filter quite easily, so servicing is not a problem.



This shot shows the brazed plate heat exchanger (imported from Taiwan via the US) with all plumbing connected. The coolant enters from the top and exits at the bottom of the exchanger. Fuel (waste veg oil or “wvo”) enters at the bottom and exits at the top. This is called a contra-flow setup, and makes the most efficient use of the heat from the coolant. I found that it was not necessary to move the windscreen washer tank or the self-levelling suspension system’s hydraulic oil tank, as all the hoses fitted comfortably around and under the tanks.


From the heat exchanger, the heated WVO then goes through the Delphi CAV filter and from there to the Pollak valve (US made) for distribution to the lift pump on the IP. The Pollak valve is controlled from a switch on the dash.


This shot shows the connection from the lift pump to the injection pump, or IP. The line is transparent to allow me to see if there are any air leaks in the system. Air leaks will immediately be revealed by bubbles appearing in the line. Normally this supply line goes to the stock Mercedes filter before being routed to the IP, but the fuel is now filtered before it enters the lift pump, so this is no longer necessary. The glass pre-filter on the diesel supply line is just to the left of the transparent line. This transparent pre-filter is important as it also helps to detect air in the system. Additionally, it is important as it monitors any algae (“diesel bug”) build-up in the tanks which is a natural occurrence in oil fuels, but of course must be eliminated.


It was convenient to utilise the stock three-way return-line banjo fitting on the stock filter housing to route the overflow lines back to the Pollak valve. However, to eliminate air and facilitate priming this particular set-up required that the venturi hole in the three-way fitting had to be blocked off. I did this using metal epoxy. The rear of the CAV truck-style filter for the WVO fuel circuit is in the foreground. I have been asked why I have the two filters, and not just the one? After all the Delphi does have 4 fuel ports. The simple reason is that fuel changeovers are more rapid this way, as the fuel in the filter does not have to be used up before full changeover occurs.


The WVO tank is in the boot. I have two of them for easy changeovers and handling. Honda bayonet fittings ensure easy, no-mess changing of the tanks. They are restrained by “occie” straps and a bar that slips into a recess under the tank. In due course, I may decide to use these outboard tanks for the diesel fuel and put the WVO in the main tank. At the moment, it has all to do with the ease of fuel handling, and this system allows me to refuel the tanks out of the car. It also allows me to use a brew-heater under the tank overnight in mid-winter to prevent the possibility that cold temperatures could gel the WVO.

2 comments:

Anonymous said...

great site, I have a 300TD wagon that I am about to convert to wvo. I've been using biodiesel for several years but this looks a lot easier!
Do you have a contact for where to get a FPHE?

oztayls said...

Yes, I chuckle to myself when I read about the hassles the guys have making Biodiesel. It can be so simple just to use straight vegetable oil (svo), new or used!

Check out eBay for those FPHEs. A friend of mine sells them. His eBay user name is aussieoudist. He sells a great 20 plate unit and is totally reliable. Contact him here
http://myworld.ebay.com.au/aussieoudist/

Regards
Bruce