Gear Guru: Everything you need to know about 4×4 gauges

By Evan Spence 8 Min Read

With all of the electronic wizardry inside of your engine these days, it’s more important than ever to keep a close eye on things. With your stock 4X4, you’re lucky if you even have a simple temperature gauge. Maybe an oil pressure or voltmeter if you have an up-spec model. While that might be fine for your average user, it’s most definitely not enough for the four-wheel driver who demands a lot from their vehicle.


With a few extra gauges installed, you are not only providing yourself with vital information. You are protecting your engine from a potential catastrophe. Here is the Unsealed 4X4 guide to the gauges your four-wheel drive needs, and the best ways to install them.

Voltage gauge

A voltage gauge is going to help modern four-wheel drivers in more ways than one. Not only can you monitor the voltage levels of your starting or auxiliary battery (if fitted) while stationary to avoid discharging them too low, but you can keep an eye on their state of charge as well. Your vehicle’s alternator generates charge. If the alternator is faulty, it will actually overcharge. This will quickly cause your batteries to self-destruct, as they literally start to boil. In most cases, the culprit will be a component called a voltage regulator. Without a gauge fitted, you wouldn’t notice a thing until it was too late and the battery was destroyed. This is not what you want to find out at the start of a week-long beach trip in summer, with a fridge full of food and drinks that need chilling.

Boost gauge

There are two main types of boost gauges, mechanical and electronic. Mechanical boost gauges are quite simple to install and require a feed from the vehicle’s vacuum line. Electronic gauges work in a similar manner. But the vacuum line is run to an electronic sensor and an electrical cable is then run to the back of the gauge to send a signal. The advantage of electronic gauges is the fact there is no chance of the vacuum line being crimped or damaged while being run through the vehicle’s firewall.


Modern turbo-diesel engines rely heavily on turbochargers to get them moving. Drive any small-capacity but high-output turbo-diesel engine and you will know what we are on about! Because so much pressure is placed on turbochargers, things can start to go wrong very quickly. Especially if not monitored. This is why we always recommend fitting a boost gauge to any modified turbo-diesel-powered vehicle.

EGT gauge

An EGT gauge monitors the air-fuel ratio of the vehicle. To install an EGT gauge, a probe is required to be inserted into the vehicle’s exhaust system. This measures and reports temperatures. For a more accurate response, the preferred method is to install the probe in the exhaust manifold before the turbo. However, the majority of installations will be post-turbo into the dump pipe. This is purely because it is an easier location to access, and many aftermarket exhausts will even come with a spare welded-in ‘bung’ so a probe can simply be screwed into place.

Ensure to research safe EGT levels for your vehicle and pyrometer location. If the probe is installed in the manifold, expect to see higher EGT levels compared to installing it in the dump pipe. This is because the turbo will actually cool exhaust gas temperatures as they flow through it.

Water temperature gauge

Have you ever noticed the temperature gauge found in your dash cluster tends to hover around the same place all the time? And only spikes when things get really hot? Most of the factory-installed water temp gauges have a ‘dead spot’ where nothing much happens. All of a sudden you’re in the red and it could be to late for your engine!

Both mechanical and electronic water temperature gauges are available. Choosing the one that works for you will come largely down to personal preference. The consensus is mechanical gauges can be more accurate. But are more involved to install as a capillary tube and bulb (what measures the water temperature) need to be mounted somewhere on the vehicle. Digital or electronic gauges tap into the vehicle’s temperature sensors. And are easier to install if you have a comprehension of 12V wiring. If not, a professional auto electrician will be able to handle everything.

Oil pressure gauge

An oil pressure gauge measures oil pressure on the output side of the vehicle’s oil pump. Oil pressure is what keeps mechanical parts from making contact with each other. Decent oil pressure will ensure internal moving components have a layer of oil film between them to avoid failure from a lack of lubrication.

If low oil pressure is experienced, it could be due to large clearance irregularities or wear on main bearing journals. It could also be due to low oil levels in the sump, meaning the engine is burning oil or has a leak.

Installation will vary depending on the choice of an electrical or mechanical oil pressure gauge. Many people stay away from mechanical in this instance, as an oil line will need to be run inside the vehicle. If something goes wrong, the idea of having hot oil spraying the interior of a vehicle is particularly unappealing.

Professional install

The positioning of an automotive gauge can be just as important as the actual gauge itself. After all, there isn’t much point in having a gauge to monitor things if you put it somewhere completely out of vision. Legalities play a part here too, as you can’t install gauges on the dash, above steering wheel height and in some states, even mounting them to the vehicle’s A-pillar is a big no-no. Look for spaces in the dash that are blank or even have accessories such as an analogue clock which you might not use all that often. Get creative and remove those unwanted accessories if they make space available for your gauges. This way you’ll have all the information you need to know what your engine is doing, while keeping it running smoothly in the process.

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