There has always been the thinking when it comes to older diesels, that more fuel means more power. This thinking is also usually accompanied by the old ‘she’ll be right’ mentality. The big downside to winding more fuel into any diesel is it often creates excessively high EGTs if not done correctly, and that of course can be detrimental to your motor.

One of the most common mods these days in any truck is the fitment of an EGT gauge. Whether it’s in your old 12HT 60 Series or in a new D-MAX, it’s a cheap peace-of-mind mod that takes an hour to fit. Your EGTs can be monitored with your new gauge, but it’s not going to alter the engine’s tune. So it begs the question; what is involved in setting your engine up so you don’t have to worry about how hot it’s going to get under full load?

Let’s look at five ways to reduce your EGTs. They aren’t all going to cost you money, some are just things that everyone can do to keep the temps down and all are guaranteed to make for a longer lasting engine.


EGT stands for Exhaust Gas Temperature and it refers to the temperature of the gases as they come out of the head. Temperatures can be measured differently between turbo and non-turbo engines depending on the location of the temperature probe. The EGTs on a non-turbo engine can be measured at different positions, either in the collector on extractors or in the exhaust manifold on engines with a factory manifold. Where the EGTs on a turbo engine are usually measured at the turbo dump pipe.


Every motor is different in the way it makes power and how it deals with the heat of combustion, so what is considered ‘safe’ can vary between vehicles. Understanding that, if your EGTs max out at 450°c – generally speaking – it’d be safe to say your engine is making healthy, reliable power and shouldn’t experience overheating issues.
At 550°c it’s time to back off the loud pedal because you’re starting to enter warmer waters. Some cooling systems won’t be able to deal with that much heat long-term. The engine will be making good power but you will have to drive it cautiously when fully loaded or driving up long hills and if you’re seeing 650°c or higher regularly, it’s hot. It’ll go like a bat out of hell but it’s only a matter of time before something lets you down.

[dropcap]1[/dropcap]DRIVING STYLE
Backing off the loud pedal is the cheapest and easiest way to reduce your EGTs. As easy as it may seem for us to say this, it actually works. Even with an aggressive rich tune, if you know the limits of your motor and cooling system, you can prolong the life of your engine just by knowing when to back off.
A perfect example is you know THAT kind of hill; it is a nice big gradual slope that is a 5th and punch it kind of hill. That is unless you are loaded with the missus and kids plus a weeks’ worth of gear and a full tank of go juice, then it becomes a wind her up and work it up the hill, kind of hill. This is when your EGTs could easily pump up around 550°C to 600°C.

To stop this, just drop down a gear and wash off a bit of speed. Yes you will be going that bit slower, but the engine won’t be getting over fuelled and working hard to try and burn it all. Instead, it will be burning everything that gets pumped into it by revving that bit harder. The benefit of this is that it will be sucking plenty of air in through the turbo and be pumping the spent gases out quicker rather than labouring to get the fuel in and the gases out.

[dropcap]2[/dropcap]SERVICE YOUR AIR FILTER
A cheap fix for excessive EGTs is changing your air filter regularly. When the filter is blocked the engine isn’t getting the right air to fuel ratio and then begins to run rich. This is because your injector pump still puts in the same amount of fuel, whether your filter is clean or blocked, but if it can’t get enough air it will run hot. It’s as simple as cleaning or replacing your filter element every time you service your 4WD.

[dropcap]3[/dropcap]EXHAUSTING WORK
If you’ve extracted more power out of your engine, such as by fitting a performance chip or larger turbo, you may have issues with excessive EGTs if you don’t also upgrade your exhaust. This is because the engine is not able to push the exhaust out quickly enough. One fix for this is to get yourself an exhaust system. A good rule of thumb is half to three quarters of an inch bigger in diameter than the factory exhaust. That said, the more power the engine is making the bigger the exhaust needs to be. This will allow the gases to flow, reduce back pressure in the system and in turn reduce your EGTs.

[dropcap]4[/dropcap]FIT AN INTERCOOLER
If your 4WD is turboed, fitting or upgrading your intercooler will go a long way to reducing EGTs. Turbos by nature produce heat when they compress the intake air, and the job of an intercooler is to cool it back down. It is possible to lower EGTs by as much 50-100°c by fitting the right intercooler.

[dropcap]5[/dropcap]TUNE IT UP
A good tune carried out by someone that knows what they are doing is the most effective way to reduce your EGTs. Getting your fuel pump set-up whilst on a dyno with all the probes and gauges attached is a sure way to have all the air/fuel ratios, injection timing and EGTs set so it delivers the right amount of fuel at all times. Whether it is on an old mechanical pump or a newer common-rail one, you will always have the same result from a bad tune: too much fuel put in and too much heat coming out.


If you don’t have an EGT gauge in your truck, get one. Even a standard engine can develop problems (such as a leaking fuel injector) that can lead to engine damage, and being able to see it coming gives you a chance to do something about it. A quality gauge will give you that extra peace of mind. It’s seriously cheap insurance!

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