There are many things that you can check visually around the car but to monitor the engine effectively requires additional gauges. I decided to fit a comprehensive range of gauges to cover EGT, coolant and oil temperature and oil pressure.
The first step was to consider how to fit the gauges into the discovery dashboard which doesn’t lend itself to additions very well.
The standard 52mm round gauges are plentiful but other than a ‘pod’ mounted on the top of the dashboard I couldn’t see a way of fitting them. Running the capillaries from here would have been very difficult.
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When I saw the measurements of the display unit I felt that these would be ideal to fit in the overhead pocket above the driver. However once I got them and started to play around I decided to fit them in the centre console in place of the pop out cup holder as they just fitted so perfectly and getting the wires there was relatively easy. |
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TIP: If you’re thinking of doing this make sure you order the longer length sensors otherwise you will not have enough length to reach. The pressure sensor can be extended with normal auto cable but the others can’t |
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TIP: make sure you clearly mark either end of each sensor so you know which is which. This is most important with the 2 temperature sensors which are identical |
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Once these were bundled together I put jumper leads across all the common connections (+ve, -ve, headlight dimmer supply and alarm buzzer feed). The supplied instructions are very clear which is which and are very easy to follow (you can download them here). I left 4 lengths of cable running from each of these to connect up when ready |
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I refitted the cup holder frame back in whilst threading the sensor wires and my 4 trailing leads through the holes made. The sensors are simply connected to the back of each gauge, following the instructions, by spade connectors and terminal screws. Connecting the +ve & -ve will now give an indication on each of the gauges. It is difficult to label each of the gauges so I decided to use a different colour for each element. Red = EGT, blue = coolant and green = oil. It is easy to differentiate between the oil temp and pressure because of the variance in readings, with the oil pressure having a decimal figure on the display. The gauges were then pushed back into the holder frame. They are a good, tight fit and although I doubt that they will come loose I shall secure them. I will detail how I do this later. The next step was to connect the sensors. |
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The EGT sensor can go before or after the turbo although most people fit it before as this gives a better indication of any potentially dangerously high temperatures that could damage the turbo. On a Tdi the simplest place to fit this is into the EGR blanking plate. I had already removed my EGR and so this was straight forward. Be warned these bolts can be a swine to remove. Make sure you soak them well in penetrating oil well in advance. I found it easier to undo them when they were hot (although you obviously need to be careful). Once removed I drilled the plate with an 11/32” drill (8.7mm is equivalent) and tapped the hole with a 1/8 NPT tap. Most aftermarket, automotive sensors are 1/8 NPT. However don’t blame me if yours aren’t. |
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The gasket was fitted and the plate bolted back on. The sensor cable was tie wrapped against the bulkhead. When you start the engine the temperature immediately rises to 150-200 C and is incredibly responsive to throttle movement. Normal driving gives a temperature range of 350 – 600 C although if you ‘floor’ the throttle it can easily exceed 700+. As a result of this I don’t intend to alter the fuelling of the car (something I had planned to do). It is easy to control the temperature with only a minor movement off the accelerator causing a significant drop. I try to drive with the gauge reading between 400 – 500 C using the gauge like the old fashion vacuum econometers. Level cruising at 55 mph shows about 470 C on the gauge |
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Following the experience in Morocco I wanted a more accurate water temperature gauge. At the same time as fitting these gauges I also fitted a low coolant alarm. The supplier of that system, Haydn, provided an in-line sensor housing which fitted into the top radiator hose. This was tapped with a 1/8 NPT thread and the water temp sensor was fitted here. The cable was tie-wrapped under the radiator top shroud and around the inner wing. This gauge register ambient temperature for the first 2-3 miles until the thermostat opens (thus showing that the thermostat is working). After this it then shows a steady 79-80 C. |
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Oil temperature and Oil pressure The engine is already fitted with a low pressure sensor which is mounted in the oil filter housing. If I was fitting only one gauge I would have used a tee piece in this position and added the gauge there. However to measure oil temperature it is better to have the sensor directly in the flow, rather than down the end of a tee. As I wanted to fit 2 gauges a tee on a tee did not seem like a good idea.
The best time to do this is when you a re planning to change the filter anyway, during a service. It is difficult to get a spanner in there to tighten the plate, but with a bit of perseverance it’s possible (you will need a 1” spanner). The filter thread size is 3/4 UNF 16, make sure you get the right size. The sensor fitting took about 15 minutes from start to finish.
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The oil pressure varies from 18-20 psi when idling up to 55-60 psi when travelling along. The pressure is always a bit higher when the engine is cold. The oil temperature gradually rises up to about 91 C. In the event of a coolant loss the oil temperature will give the best indication of the actual temperature of the engine. |
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The filter sits about 1" lower than normal but there is still plenty of clearance above the diff and axle. |
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EGT alarm comes on at 700 C and goes off at 690 C Water coolant alarm comes on at 100 C and off at 95 C Oil Temp alarm comes on at 110 C and off at 100 C I haven’t set a high alarm for oil pressure. I will monitor the ‘normal’ temperatures over time and these set points may alter. The end result is a nice neat installation which almost looks like it was designed to fit. The displays aren’t too bright so as to distract at night and they are automatically dimmed with the dashboard lights. |
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With the exception of boost pressure, I now feel really comfortable that I know what is going on inside the engine at all times and I will get an early warning of any potential problems. From start to finish this whole job has taken about 2 days to complete due to the fiddliness of the task and the need to get things right. Please note; you do have to spend a bit of time ‘programming’ each gauge to match the sensor fitted. This is done with the 3 buttons on the front. It is quite straightforward but you do have to follow the sequence correctly. If you don’t you can end up with some very strange readings (for the first 20 miles my engine never went above 36 C!). I would recommend this to anyone who is thinking of fitting additional gauges. |
In the end I discovered 
Auber sell everything I needed so in the end I ordered 4 display units (1 red, 1 blue and 2 green) a ‘K’ type thermocouple (EGT), 2 P100 temperature sensors (oil & water) and a 70 psi MAP sensor (oil pressure). The total came to $377 (about £240) which is comparable to other options. It took about 10 days for the items to get here.
The first step was to pass all the sensors through the bulkhead between the engine and passenger compartments. I did this high up on the driver’s side just outboard of the brake reservoir.
I then taped the four gauges together using insulating tape (I needed small spacers between the units at the back to keep them straight. I use some 1mm scrap plastic bits I had kicking around). 
Next I removed the pop out cup holder from the dash and dismantled it completely. The bank of gauges fitted almost exactly where the slide out part came out. I used a dremel to shape the plastic a little bit and to cut a slot for the wires.
Exhaust gas temperature
The sensor fitting was inserted and the compression nut and olive fitted on the probe. The sensor shouldn’t touch the side of the manifold so I bent mine slightly with 2 pairs of pliers (do this after you put it through the fitting or you may have trouble). Another tip here is to drill the hole higher on the plate as this will give you more room due to the angle of the manifold.
Coolant temperature
I turned to the world of the ‘boy racer’ and bought a 
TIP: Fit the sandwich plate to the temperature sensor first to prevent the sensor cable twisting. Then twist the pressure sensor cable in the opposite direction so that it ‘untwists’ as you screw it in. Then fit the plate to the filter housing. This will keep the cables much neater.
Once fitted the filter simple screws on as before. 
Each of the gauges can be set to display fahrenheit or centigrade (I prefer C) or psi or Bar (I prefer psi) and is capable of having a high alarm set which operates a red light on the front of the gauge and can activate a 12v buzzer. I have set them as follows:
I bought a .
