Andrew's Cars.
I have owned a number of cars since my first in 1987 including a Peugot which ran on cooking oil. My current transport is a Citroen C3 Pluriel.
Principle of Converting a Diesel Engine to Run on Vegetable Oil.
Problems Running a Modern Car Diesel Engine on Vegetable Oil
My cars, in chronological order:
Oct 1987 - Feb 1988
Citroen Dyane 6
Feb 1988 - Jun 1988
Citroen AX GT 1.4
June 1988 -
Citroen Dyane 6
Citroen 2CV6 Special Beachcomber
Citroen GS
Vauxhall Chevette L
Saab 900
- Nov 1996
Citroen BX Athena
Nov 1996 - Feb 1997
Vauxhall Cavalier
Feb 1997 - May 2003
Citroen Xantia LX
Feb 1991 - Aug 2000
Citroen 2CV Special
Aug 2000 - July 2001
Citroen AX GT 1.4
August 2001- October 2006
Peugot 405 Style 1.9D
Converted to vegetable oil October 2002. First used on the road with vegetable oil in December 2002.
I chose the car above for conversion because it is relatively simple as modern diesels go. It is normally aspirated (non turbo) and uses a Bosch injection pump to deliver fuel to mechanical injectors (i.e. it is not a common rail diesel).
May 2003 -
Citroen Picasso SX HDI
October 2006 -
Citroen C3 Pluriel
Principle of conversion of a diesel engine to run on vegetable oil.
Most modern Diesel engines run on mineral oil. The first diesel engine shown to the world by Rudolph Diesel in Paris in 1901 (?) ran on peanut oil. Modern automotive diesel engines are designed to use mineral oil. With the exception of older Mercedes diesels, modern cars need a few modifications to run on vegetable oil because vegetable oil is more viscous than mineral diesel fuel and has a higher flash point. I wanted to run my vehicle on an environmentally friendly fuel.
Problems Running a modern car diesel engine on vegetable oil
At ambient temperatures vegetable oil is more viscous than mineral diesel fuel. Thus, the injection pump must work harder to draw the oil from the fuel tank. The vegetable oil also has a higher flash point (the temperature at which it ignites). If it is used in a cold engine, the engine is difficult to start and liable to suffer from coking up. The extra load placed on the pump from sucking the more viscous oil can cause it to fail. It would appear that Lucas-CAV injection pumps are particularly prone to this problem while Bosch equipment is less prone to it.
To resolve the viscosity problem, the vegetable oil can be heated. At 80 degrees C, cooking oil has the same viscosity as mineral diesel fuel at 15 degrees C.
The oil can be heated with engine coolant, electrically or using heat from the exhaust. I opted for the engine coolant because its temperature is controlled (a great deal of engineering has gone into ensuring that the engine coolant temperature is maintained at about 80 degrees C) and it places no additional load on the engine.
Experience of members of the vegoil-diesel discussion group and many others around the world has shown that Bosch diesel injector pumps and their derivatives are suitable for conversion to vegetable oil.
In order to ensure that the engine can be started easily and there are no problems with coking, I decided to retain the existing mineral diesel fuel system to start and warm the engine.
Vegetable oil is kept in a second tank in the boot, supplied with heat by a branch from the engine cooling system. A copper pipe acts as a heat exchanger inside the vegetable oil tank.
Many thanks to Joshua Tickell, author of "From the Fryer to the Fuel Tank" http://www.veggievan.org/book/ and all the members of the UK vegoil-diesel group on http://www.groups.yahoo.com/
The coolant flows from a point in the engine bay supply to the interior heater (the hose here which goes off the left of the Fig. 1),
Fig 1. Engine Bay Right Rear.
through a hose, inside which is the vegetable oil supply pipe (hose-in-hose), which ensures that the oil temperature is maintained on its way from the tank. The coolant flows through the vegetable oil filter (left hand side of Fig 2) and then through the tank heat exchanger and then is returned to the return side of the heater (through the hose on the top left of Fig 1).
Fig 2 In The Boot. Vegetable Oil Tank and Heated Fuel Filter (tank lagging removed for clarity).
Fig 3 Engine Bay Left Rear. End of the hose-in-hose. Here hot coolant flows from the engine into the oil heater circuit via the hose-in-hose. A domestic central heating radiator air bleed valve is fitted here to permit the removal of air-locks.
Before conversion, the mineral diesel fuel was drawn from the tank by the injector pump via the fuel filter and supplied to the injectors under high pressure. About 90% of the fuel drawn from the tank is returned to the tank unused. After conversion, supply of fuel to the engine is controlled using two Pollack electrically actuated valves (Fig 6). A six port valve switches the feed and return to the pump between the original and vegetable oil tanks and a three port valve switches the return between the original and vegetable oil tanks. This permits vegetable oil flushed from the pump and injectors before the engine is stopped to be returned to the vegetable oil tank to reduce contamination of the mineral diesel fuel used to start the engine.
Fig 4 General Fuel Feed Layout under the Bonnet. The injector pump is just below the centre of the picture. The original fuel filter is at the extreme right of the picture.
Fig 5 Close-up of Valve Arrangement.
The top valve is the 6-port one. Top half is the fuel return side. Bottom half is the fuel supply side. The red hose is the temporary vegetable oil return hose (to be replaced with an alternative in a more suitable material).
The bottom valve diverts the diesel return to the vegetable oil tank while flushing before stopping the engine after running on vegetable oil.
Fig 6. Insulated Hoses Run Through Passenger Compartment. This was done to avoid drilling holes in the bodywork.
Plumbing Diagram
Electrical Diagram
There is no appreciable difference between running on mineral diesel fuel or vegetable oil. In use, the engine is started on mineral diesel fuel and run until normal operating temperature is reached. By this time, the vegetable oil line and fuel filter have been heated with the engine coolant. The driver then operates the switch which actuates the six port valve. Fuel is now being drawn from and returned to the vegetable oil tank. About a quarter of a mile before stopping the engine, the three port valve is actuated with another switch to divert the mineral diesel return line to the vegetable oil tank. The six port valve is then switched to mineral diesel position. Mineral diesel is now being drawn from the original tank and flow returns to the vegetable oil tank so that no vegetable oil reaches the mineral oil tank. When the engine is stopped, the three port valve is returned to its original position, sending the mineral diesel fuel return back to the mineral oil tank.
Parts and Assembly:
Vegetable Oil Tank.
Source: http://www.marineonline.co.uk/
42 litre marine fuel tank constructed from high density polythene.
Modifications from original spec:
Added heat exchanger made from 15mm copper pipe.
Note: Make sure the heat exchanger can be inserted into the tank through the aperture. I had to cut this one in half and then join it together again inside.
Be sure to pressure test the heat exchanger to make sure it doesn't leak.
Added fuel gauge sender. Salvage from another car of the same model.
Heater hose for the hose-in-hose.
20mm ID car coolant hose from Braunston Bottom Lock boat chandlers.
Heater hose for the coolant return from fuel tank.
16mm ID car heater hose from Braunston Bottom Lock boat chandlers.
Fuel line for hose-in-hose and fuel return line to secondary tank.
12mm OD nylon hose from Regent Hose, Milton Keynes.
Pollack Motorised six-port valve.
from JC Whitney www.jcwhitney.com
Pollack Motorised three-port valve.
From JC Whitney www.jcwhitney.com
Sundry plumbing parts.
Parts required for the hose-in-hose.
2x straight 15mm to 12mm compression reducing connectors. Used to make the join between the inner hose (fuel) and the outer hose (coolant). The smaller end of the compression fittings must be drilled out to permit the 12mm hose to pass through instead of simply joining the end.
2x 15mm - 15mm - 22mm tee adapters to join the compression reducing connectors to the 20mm ID car heater hose and 16mm ID car heater hose.
Parts required for the secondary tank heat exchanger.
2m 15mm copper pipe.
2x ball valves. The valves themselves were not required. The tails used to attach the valves through the side of the toilet cistern were used to connect the heat exchanger to the plumbing outside the secondary tank.
2x washing machine tee valves. These were used to fill the heat exchanger and vent air from it.
2x 15mm tap connectors. Used to connect the heat exchanger to the ball valve tails inside the tank.
1x straight 15mm compression connector. Used to connect the two halves of the heat exchanger together inside the tank.
Heated diesel fuel filter.
Local scrap yard. Taken from Peugot 504 2.3D.
Modifications from original spec:
Removed thermostatic valve from coolant inlet and drilled out to 10mm ID.
Electrical.
Connectors, wire, changeover relays, buzzers and lamps from Maplin Electronics.
In the UK, running a car on the road a liquid road fuel on which duty has not been paid is an offense for which HM Customs and Excise will prosecute you if you are caught doing it. .
