Mechanical Tips


More Power

By Nathan Johnson | 14 September 2023

Since the creation of the internal combustion engine, finding ways to generate more horsepower, kilowatts and torque from them has been forever evolving.

So, let’s break down these terms and what they represent in an engine.

Horsepower: This is a measurement or a rate at which work is done and customarily used to reference the output of engines and motors. The term was adopted by a Scottish engineer, James Watt. He was determined to compare the output of a steam engine to that of a draft horse. So, with a bunch of mathematical equations, he worked out how many horses it would take to get the same output as the steam engine. Therefore, we have the term Horsepower.

Kilowatts: Modern-day measurement of the horsepower saw them convert the output into

Watts, and by definition, 1 Kilowatt equals – 1000 Watts, 1 HP equals 0.7457Kw.

Torque: Referred to as a moment of force. It is said to describe the moment of change of angular momentum imparted to an isolated body. It was Archimedes who used levers to push and pull a linear force applied to a body. Torque can be considered a twist of an object relative to a chosen point. A few mathematical equations later, we have a measurement for torque, usually measured in Foot Pounds Ft-lb and now commonly measured in Newton Meters Nm.

How do we generate more power (insert video of Tim the Toolman grunting)? With modern-day advances in Electronic Fuel Injection, finding or delivering more power from an internal combustion engine, can be very simple but, at the same time, very complex.

When your motor vehicle was initially designed and built, an engine map was loaded into the Electronic Control Unit (ECU): the map tells the engine when to fire injectors and or ignition coils, how to adjust the Variable Valve Timing (VVT) and in some cases when to shut down cylinders to increase fuel economy. All this and more is happening inside the ECU; it sends and receives information from sensors all over the engine and transmission to give you the optimal driving experience required to enjoy driving your car.

By adjusting the engine map, we can move the timing at which the engine fires and how much fuel it can deliver, adjust valve timing to stay open longer or shorter, take away throttle lag in the throttle pedal and throttle body, adjust transmission shifting, and loads more variables. Some performance gains will require modifications to the engine, which your desired outcome will determine. You may want to be able to run a race-defined fuel like E85 and a pump fuel like ULP98; if this is the case, for example, you may require a fuel system overhaul to be ethanol-compatible.

Other mechanical upgrades maybe tuned-length exhaust headers, high-flow catalytic  converters and tuned exhaust systems, and cold air induction with an air filter with high flow capability. In looking for a much higher increase, you may want to upgrade to a supercharger or turbocharger used to force the air into your engine, resulting in much higher power increases.

All of the above is relative to petrol fuel-injected vehicles. What about modern-day diesel?

The modern-day diesel is no slouch; technological advances, like the petrol engine, have also evolved. Once a diesel engine was a true workhorse, they loved to load and lug along, being

able to generate high torque at low RPMs. The slow burning of the diesel fuel combined with a long stroke in the diesel engine delivered that torque.

Now, to deliver a more efficient diesel engine, I will go out on a limb and say there would be a few that do not have a turbocharger attached to them. The ability to squeeze more diesel and air into the combustion chamber gives the engine more power, much quicker and can run more efficiently. The turbo provides each cylinder with as much filling as allowed, and the Common Rail Fuel Injector sprays a high-pressure atomised diesel that mixes with that squeezed-in air to create the firepower the engine requires.

How do they increase the power of these engines? Like the petrol engine, the ECU has a map set out by the manufacturer. The relative tuner can adjust the map to change the timing of componentry in the machine, allowing more turbo boost, opening the injectors for longer to deliver more diesel and changing a few signals to and from the ECU on select sensors around the engine bay.

You may need mechanical upgrades as well with diesel tunes, and typical upgrades include larger diameter exhausts to assist in letting the exhaust flow much better, cold air induction like snorkels, larger surface intercoolers and, in some cases, depending on your desired outcome, bigger common rail injectors and turbo upgrades.

Consider more upgrades to drivelines and brakes for petrol and diesel power increases. Talk to your preferred tuner about these upgrades, and they can suggest what will work for

your setup.

Mechanical Failures

Mechanical Failures

By Nathan Johnson | 1 September 2021

Why did that brand-new part recently installed fail so soon? – Mechanical failures, a question that is always asked when this occurs, and rightly so.   

In essence, nearly all mechanical components fail in their lifetime. Whether that life is a few kilometres or a few hundred thousand kilometres, it will eventually fail.  

I have had the pleasure of working with some very clever Mechanical Engineers in my time, particularly during my tenure in the mining industry. These engineers gave me an insight into Condition Monitoring, and the benefits of looking at oil samples, filtergrams, vibration analysis, and Non-Destructive Testing (NDT) reports. 

The consideration in particular which caught my attention is the life of the machine components and how the planners work out when to change them before failure. 

The way it was explained to me was straightforward; it’s ‘The Bathtub Principal.’ 

The life of any component can be very long or very short. It is measured by expecting a new or reconditioned part to fail very early (infant mortality) or at the end of its life (worn out). The probability is relatively high at the start and then becomes very low as the part moves past the infant mortality period and into service life. It then becomes quite high again at the end of life when it becomes worn out. 

When it comes to using quality parts on your vehicle, it is always sound advice to understand the warranty that comes with the components and what the manufacturer will cover when it is time to lodge a claim against a faulty part. Buying your parts from the world wide web is becoming popular, driven by a desire to save on costs. We see a large number of mechanical failures from parts bought this way. My advice is to buy from a reputable company with a warranty that is comprehensive and easily accessible, ensuring the business can be contacted when you need them.  

As the saying goes… poor man pays twice. 

Oil Catch Cans and Diesel Filtration

By Nathan Johnson | 26 April 2021

A common add on to most newer 4WDs is an Oil Catch Can and a Secondary Fuel Filter. If you are sitting on the fence regarding fitting up either of these features, please read on.

Oil Catch Can

Let us start with why we would install a oil catch can. One of the first emission controls to become popular on all petrol and diesel engines was a system called Positive Crankcase Ventilation (PCV). This allows the positive pressure created in the engine’s sump to make its way out via a PCV valve usually mounted in the valve cover of the engine. This positive pressure released via the PCV valve has oil mixed with it and requires the engine to keep this oil contained, so it does not end up on the pavement whilst driving or parked. The PCV valve is connected to the air intake piping/manifold so the engine can burn this vapour off and out the exhaust it goes. It sounds straightforward, and yes it is.

Now let’s enter into the 20th century, and we are now governed by a worldwide set of emission control rules for our motor vehicles set out by a governing body that’s role is to lead us to zero or close to zero emissions.

Let me introduce to you the Exhaust Gas Recirculation System (EGR). The EGR is exactly what the description says it does. You may be wondering why we would want to recirculate our exhaust gasses? This is to further reduce noxious gasses from our engines. It has been said that if we recirculate the exhaust back into the combustion cycle, it will reduce those noxious gasses, therefore, reducing our carbon footprint. In a nutshell, the exhaust is sent back to the intake manifold, and at certain operating conditions, the EGR valve will let the engine eat its own exhaust.

Now mix these two together, (PCV and EGR), and what we end up with in most diesel engines is a very thick paste that blocks up your manifold, restricting airflow and impeding your vehicle’s performance.

So what does the oil catch can do to help? It takes away the oil that is the by-product of the PCV and sends it through a filter allowing the vaper and pressure to return to the intake. This means that the EGR can operate as intended, and the PCV is now being filtered. The catch can is then drained at your service intervals.

The Secondary Fuel Filter

Doesn’t my vehicle already have a fuel filter? Why would I need a second filter?

To put it bluntly, Australia has inferior diesel fuel quality. I do not believe that we make any diesel anymore on the east coast of Australia, and therefore the majority of it is imported vie vessels from overseas. This type of fuel handling, in my opinion, is very loose and would introduce many contaminants into our vehicles.

The standard filter on your 4WD is very good; most are filtering at 5-7 microns, even the aftermarket filters we often use during scheduled servicing are the same to meet OEM specifications. They do have a sediment function, and most have a warning light to advise you of either sediment or blockage. What they don’t do very well is separate out moisture. Moisture in the diesel fuel system is not ideal, and the diesel acts as a lubricant. A secondary filter of good quality will do that very well.

So do I fit a Pre or Post Filter? 

A diesel guru once told me that the pre-filter is a better option than the post, but they both have significant benefits, water separation. A pre filter will typically be 30 microns of filtration, and this allows for great flow to the OEM filter, and the 30 micron filter will catch all the big items and let what will pass go through to the OEM filter, knowing that it has a finer filtration rate of 5-7 microns. The pre-filter has also separated a lot of the moisture, and now the OEM filter only has to filter the fuel and not worry about moisture.

A post filter would have a similar setup though the filter would be 5 microns instead of 30. The same guru as above said to me, ‘why would you want to filter your fuel twice at the same level. The only benefit would be the water separation’. I see his point, but if you are using a filter that is not 5 microns in the OEM housing, then this set up is excellent as a second defence.

In my opinion, the pre-filter is my go-to option.

  • It separates the water early, allowing the OEM filter to just worry about fuel, and if any moisture does make it through, it will be trapped by the OEM filter.
  • Allows better flow to the OEM filter.
  • Catches the big contaminates.

There is always plenty of discussion around pre and post-filtration, and there are benefits to both of course. If you are having these discussions and have one or the other installed, you are already winning.

Johnson’s 4WD supply and install the Direction Plus range of Oil Catch Cans and Secondary Filter products. To discuss your options, please contact us via our socials, our website, on the phone or drop into the workshop.

Buying a Used Car

By Nathan Johnson | 10 June 2019

When buying a used car, making sure you’re not buying someone else’s problems can be tricky. Hopefully with these tips and tricks, you can have the confidence to buy a great used car that will provide you and your family with reliability for years to come.

Planning and understanding expectations is key. Critical items you should address before commencing your search include: 

  • Budget
  • Expectations
  • Research
  • Vehicle condition
  • Finance check
  • Purchase price
  • Start from scratch servicing


Make sure you have a clear idea on what you would like to spend on your used car and take into consideration that you may want to do an initial service immediately, or there could be repairs required to ensure the vehicle is in safe, roadworthy condition. Be sure to also include initial registration and insurance costs as these will all be required at purchase time to protect your asset.


This is where you need to really decide what your needs in a car are and what your wants might be. For example, you may ‘need’ four doors and a boot and you may ‘want’ an automatic instead of manual. Being able to articulate the non-negotiable items on your needs list will assist the process in ensuring you get exactly what suits. If some of the wish list items make it into your purchase, happy days!


It is important to understand what your expectations are and conduct research to find out if you are going to be able to find your ideal car, within your budget. The following websites provide fantastic search options which look at items such as auto vs manual, style of vehicle, age of vehicle, number of kilometers etc. When comparing your budget, expectations and the research, this will assist you in understanding what you are likely to be able to afford for your money, even before you begin your search.

Vehicle condition 

When you think you’ve found the right vehicle that warrants your time and attention to inspect, ensuring you understand that the way in which the vehicle is presented is not the only contributing factor to whether the vehicle is a good buy, is essential.

If you are not mechanically trained, take a friend or family member with you for support, as well as a torch as there are some key items you can check for yourself, before obtaining an opinion from a qualified tradesperson. Some key items to check are:

  • Use your torch to look under the engine for oil leaks. Don’t just check the top of the engine as it can be common for some sellers to degrease the top of the engine for sale purposes. 
  • Check the dipstick as grey or milky oil can indicate an engine problem.
  • Check the coolant by taking the radiator cap off. There should be no oil in the coolant, and it should be brightly coloured and clean. 
  • A quick check of the radiator cooling fans and the battery for corrosion and other damage is also essential. 
  • Check that there is a spare tyre, jack and toolkit. 
  • Inspect the paint and panels on the vehicle for colour differences and panel alignment. If panels don’t fit properly or doors don’t open and close with ease, this could indicate the vehicle had been in an accident. 
  • Check the tyres for adequate tread (3-4mm) as well as uneven wear. There could be an issue with the alignment, steering or suspension if the wear is not consistent. 
  • Inside the car check for wear and tear on the upholstery, trim and carpets. Of course, when purchasing a second hand vehicle there is going to be general wear and tear, but as long as you’re comfortable with the state the inside of the vehicle is in, that is ok. 
  • Check all the seatbelts to ensure they work properly and look for car seat bolts if required. 
  • If you take someone with you when inspecting a car, ask them to help you check that all lights and accessories work. Do this by turning the key onto accessory and testing every feature on the dash including hazard lights, indicators and brakes. 
  • When you test drive the vehicle, listen for noises, rattles and knocks. This can be a good indication of a problem. Also watch for excessive exhaust fumes when starting the engine and idling. 
  • Take good notice of the dashboard when test driving to look for any warning lights that may appear. 
  • Test the brakes a few times on the test drive as well as they should feel firm.

When you decide that you want to proceed with an offer and you need a tradesperson to double check the vehicle, don’t hesitate to contact Johnson’s 4WD Repair Shop as we offer a mobile mechanical service and can complete a pre-purchase inspection for you from as little as $110. We can also assist you or the seller in obtaining a Roadworthy Certificate.

If there are some items that need attention and the seller is open to negotiation, a reduction of the purchase price on the proviso that you fix what needs to be repaired could see you walk away with an affordable and reliable vehicle within budget and which meets all your needs. If the seller isn’t negotiable and there are too many expenses resulting in the purchase price of the vehicle increasing significantly after the transaction is complete, it may be best to move on to another vehicle.

Finance Check

If purchasing from a private seller, it pays to complete a REVS check online. This will show you if the vehicle is currently held as security with a finance company or bank. If it is, the vehicle isn’t legally able to be sold. A REVS check will also show you if the vehicle has ever been ‘written off’ in an accident.

You can obtain a REVS check from here:

Purchase Price

Negotiations on the final purchase price can begin once you have completed the above steps and are confident in the vehicle you are making an offer on. Making an offer too soon can result in backwards and forwards negotiations and may result in wasting your time as well as the sellers. If you make an offer and the seller’s counteroffer is the advertised price, unless you are really keen on the vehicle, it may be best to move on and resume your search.


Be sure to write a receipt if the transaction is completed by a private seller and be prepared to complete a Registration Transfer with the QLD Department of Transport and Main Roads.

Receipt template examples can be found online with a quick google search. The seller should have this ready for you but it always pays to be prepared in case they don’t.

TMR Registration Link:

Start from Scratch Servicing 

After the purchase, it pays to know where your vehicle’s service history is at. If a completed logbook has been provided with the car, it will provide you with an overview of what has been completed to date, by who (you’re looking for a reputable workshop / mobile mechanic here) and will give you an indication of what is coming up.

If the vehicle does not have a logbook and the service history is not available, the ‘start from scratch service’ is what you will need. By starting from scratch, this will ensure all the oils and filters are changed and replaced, as well as service such as spark plugs, coolant, drive belts etc. Once this has been completed, you’ll have peace of mind that from then on, every service due can be done as per the manufacture’s recommendations for the intervals. Even without a logbook from the manufacturer, this information can be sourced by your trusted mechanic.

Pre-Purchase Inspections, Roadworthy Certificates and Start from Scratch Servicing can all be undertaken here at Johnson’s 4WD Repair Shop. With one on one service you can trust, quality and affordable workmanship, online booking options, free pick up and drop offs as well as text message reminders, the maintenance of your vehicle is made easy and hassle free.