How to fit a VDO temperature gauge to a Land Rover Defender
Looking around the internet, there is a lot of reported problems getting the water temperature gauge to work properly after swapping an old 2.5td for a 200tdi Discovery engine.
Ever since I have owned the Land Rover, the temp gauge hasn’t been right, so over the weekend I finally got around to sorting it out by installing an after-market temp gauge from VDO.
The VDO gauge has temperature markings in degrees Celsius, so it is a vast improvement over the original Land Rover gauge, and will allow you to keep a closer eye on temperature of the engine.
Getting the right sender
When you fit an after-market gauge you also have to change the sender unit on the engine as well. My Land Rover Defender has a 200tdi Discovery engine fitted, and the thread on the sender is different to a 200tdi Defender engine (don’t ask me why!).
So to use the old 2.5td sender (Land Rover part number PRC2505) on the Discovery engine, you need an adapter, which had already been fitted by the previous owner. This made it easy to choose the correct VDO sender, as the thread on the old 2.5td sender is 5/8 UNF.
If unsure, its best to talk to Brookwells or Paddock Spares.
Fitting the VDO sender
This is as easy job, the only tool you need is a spanner! Undo to old sender, and screw in the in the new VDO unit. You will loose a little water, but nothing to worry about.
I chose to add a new wire to the gauge as well, bypassing the old loom completely. This is an easy job too, as the wire goes straight to the gauge in the dash, and its as simple as poking the wire through the grommet in the bulkhead.
Fitting the VDO temperature gauge in the dash
The VDO gauge is 52mm in diameter, so is a direct replacement for the original Land Rover gauge. All the wires you need are already in the dashboard, but you may have to change a few connectors over like I did.
There are 3 wires to make the gauge work. They are:
- Switched positive – green (goes live when the ignition is switched on)
- Earth – black (Had to change the connectors on this wire)
- Sender
There are 2 other wires which feed the gauge light.
- Switched positive – red/white (goes live when you switch on your lights)
- Earth – black (I added in an extra wire to link this earth with the gauge earth)
Once wired up it was a case of taking the Land Rover for a run to see how the gauge performs.
The result was great, after a few minutes the gauge started to register, and then within 5 miles the Land Rover was up to temperature and was reading dead on 90 degrees Celsius. This is just right, as I have an 88 degree thermostat in the engine.
You can also watch the gauge move depending on the load on the engine. When working hard, (going uphill for example) the temperature rises slightly to just over 90 degrees, but when going downhill you will notice it reads just under 90 degrees. The original Land Rover gauge would never show these slight variations in temperature.
All in all a worth while job done, and its got me thinking about what other gauges I can fit to the Landy!
Tags: defender, How To, land rover, sender, VDO gauge, water temperature gauge
Views: 8,002
Great post and interesting to read that the temp sensors on the Defender and Discovery are different.
I know of guages to measure low water coolent which is a good one to have esp in warmer climates.
What about a guage that can monitor the gearbox temp?