Vegetable Oil Conversion - Cockpit

Anyone who has spent time round older Land Rovers knows how little dashboard space there is for things. Add in to the mix the desire for a Car Computer and auxillary switches for accessories such as lights, compressors and inverters and space becomes even more of a premium.

I decided early on in the design process that I wanted my Vegetable Oil panel seperate to all other circuits and switches to avoid any confusion over function or accidental use. My Land Rover is ex military and has the large promiment light switch arrangement in the centre of the dash, but already being fitted with switches meant I could not keep the "clean" install aim i was hoping for if used.

Underneath the military panel the previous owner had enlarged the centre panel normally used for Rear Window Wiper control to take a radio. The two holes to hold the panel were still there so I decided to craft a metal plate and fit all indicator lights and control switches here. Working in IT I have a loft full of old computers and had come across a particularly thick walled Compaq from a few years ago and decided its metal case would make an ideal switch panel. I cut out a rectangle bigger than the size I needed and used a bench grinder to shape the edges and round the corners.

Once shaped I could measure from edge to edge and divide it by the number of components I had. This would give me equal spacing between each component. Once marked up the pillar drill made quick work of the 9 holes required. The 9 holes were as follows:

2 x Holes for Fixing Bolts
2 x Holes for Red LED Panel Lights
2 x Holes for Yellow LED Panel Lights
3 x Holes for DPDT Switches

They were all equally space along its length and mounting the components could begin. Once the components were secured on the panel I could begin to solder them up following a circuit I had designed using Crocodile Clips Electronics software.

This software allows you to construct a circuit diagram on the computer and then test it with power and voltage to make sure it functions correctly. It saves a lot of time and components as any mistakes are as simple as clicking the "undo" button.

My circuit was designed to control the 12v solenoids fitted in the engine bay, which only require power when running on Vegetable Oil. When on DERV from the original tank the solenoids are unpowered. This meant using DPDT On/On switches I could have indicator lights and an alarm system to indicate if I was sending Vegetable Oil back to the DERV tank. I copied the diagram into my notebook and worked from that in the shed.

I had decided to solder my connections on the switch panel to ensure good connections and to save space in the tight confines of the components.

The alarm function of the circuit requires a couple of wires to criss cross from one switch to another but it is a very simple circuit. Four fly wires were soldered onto the switches.

These four wires provided:

  1. Ignition Controlled Power
  2. Earth
  3. Supply Solenoid Control Wire
  4. Return Solenoid Control Wire

Labelling the panel was a source of much frustration. I spent a while looking at the different options but eventually borrowed an electronic label printer and set it to its smallest size. I am unsure how well they have stuck but I am pleasantly surprised at the hold they seem to have achieved to date. I had used a similar machine in the past but the labels faded due to sunlight shinining on them, but with limited options and the shaded posistion of the panel I decided to give them another try.

The middle switch, which is currently unused and unlabelled will be used to select which tank the fuel gauge is reading. Once happy with the labels I dismantled the military switch panel and sticking my hand down the back used bolts to secure the new panel in place.

The panel lights used have a cover which makes it harder than I'd of liked to see the LEDs during the day but they are not invisible and the angle of the switches, and the guage reading from the fuel temperature sensor will also indicate tank selection.

The power was taken from the usual "white ignition" wire just behind the panel, and the earth was attached to the substantial cable used on the military test sockets above the panel. Power was also diverted at this point to the two additional gauges detailed below.

The second and only other addition to the cockpit of the Land Rover pertaining to the Vegetable Oil set up was two digital gauges. Now I admit here when ordered I thought they were blue, and it was only when my non-colourblind sister mentioned they were purple was I alerted to their true colour.

The two gauges sit as close to eyeline as possible, and far enough back not to be hit whilst steering. They are small 37mm gauges with LED display read outs for the most accurate information possible. The left hand gauge of the two displays engine coolant temperature as it enters the heat exchangers.

The right hand gauge displays fuel temperature entering the injection pump (25 celcius is the default temperature when no sensor is connected). The gauges update quickly and are showing an increase in temperature within a few hundred metres of pulling away from cold.

The gauges are wired to the same "white" ignition wire as the switch panel, and come on with the ignition. The two additions of gauges and switch panel gives little indication of the modifcations in the engine bay but offer comprehensive monitoring of what is going on "under the bonnet".

On a side note the rather consistent temperature of 76 degrees celcius I have been getting from the engine coolant makes me wonder if my 200 TDi has a working wax thermostat fitted so I am going to fit a new one shortly.



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Graeme Shorten - L4NDROVER.CO.UK -
Copyright 2014