Mitsubishi Triton Problems

Any diesel engine can be a bit noisy; that’s just the way they work. But if a new noise has surfaced, then something has definitely changed under the bonnet. First thoughts would be a hydraulic lash adjuster (also known as a lifter) that is failing and making the noise.

These lash adjusters maintain the correct valve clearance (which otherwise alters as the engine heats up and cools down) but one that fails will allow the valve clearance to grow, at which point you get a ticking noise at the top of the engine as the valve and lifter collide.

If this is the case, you’ll need to replace the offending lifter and best practise suggests you replace all of them at the same time as one failed one suggests they’re probably all worn. But it’s also important to make sure it really is a dud lifter you’re dealing with. A diesel engine has lots of potential sources for such a noise, so make sure you rule out a worn fuel pump or any other mechanical problem before ripping the lifters out.

There are a lot of possibilities here. Either there’s a problem with the actual shifter for the transfer-case (that selects two or four-wheel-drive) or there might be something amiss inside the transfer-case itself. But before you try anything else, make sure that the transmission is in Neutral. Many vehicles will not shift into or out of four-wheel-drive while the transmission is in Drive or Reverse. So stick it in Neutral and see what happens.

From memory, the 4WD selector in your ute is a mechanical lever, not one of those newer rotary knobs. So at least you won’t be trying to overcome an electronic selection problem that occurs in these later versions.

According to website howsafeisyourcar.com.au, this version of the Triton has side air-bags in both the front and rear seats. Fitting side airbags was a great move by ute makers and reflects the fact that these vehicles are being used both as family cars and as company cars where OH and S requirements require a high safety rating.

This sounds like a case of a split fuel pick-up pipe in the fuel tank. When the tank is full, the split in the pick-up is covered by fuel, so the pump works normally at supplying the injectors with fuel. But when the level in the tank falls, the split is exposed and the fuel pump suddenly finds it’s much easier to suck air rather than fuel. And engines don’t run too well on just air.

This could be interpreted by a scan-tool as a fuel leak, so a check of the tank’s pick-up tube seems like a good place to start looking. Any actual fuel leak large enough to cause this problem would, presumably, be visible, but it’s worth a check of the fuel rail and return lines as well. Failing that, you could have a dud sensor that is telling the computer there’s a fuel shortage and sending the car into limp-home mode to protect the engine (which would also explain the loss of power). It would also be worth checking to see that the new Suction Control Valve (SCV) is working properly, even though it's brand new.

If you had a loss of drive in every gear, the suspicion would be that the transmission is low on fluid or the torque converter is not working properly. But if it’s only reverse gear that is playing up, the chances are that the bands or clutch pack that locks the transmission into Reverse is allowing the gears inside the transmission to spin without actually transferring torque to the output shaft (and thence to the wheels).

That said, there could be other internal problems that could cause this, so a visit to a transmission specialist is the best advice. Don’t delay it either, as continuing to drive the vehicle in its current state could do more damage to the transmission.

Diagnosing electrical problems remotely is a hiding to nowhere, but conventional wisdom says the wiring, earths and related switches are the first place to start. But modern vehicles also rely on body computers to control some of these functions, so that's worth a check, too.

I can only hope you raised and logged this issue with Mitsubishi when it first started happening. If you did, you have what's called a pre-existing condition under the factory warranty terms. If the problem first surfaced five years ago, that would place the flickering occurring from about 2019. Which means, as a 2018 vehicle, it would have been covered by the Mitsubishi warranty. Even if the car subsequently runs out of warranty, a pre-existing condition is still legally required to be fixed by the car's manufacturer.

DPF technology is fast becoming the bane of turbo-diesel owners. The filter is designed to trap some of the nasty exhaust emissions of a diesel engine and then automatically burn them off at high temperature periodically, emptying the filter in the process. But way too often, this isn’t happening according to the script and filters are either clogging up, requiring a manual clean-out or, in extreme cases, complete replacement.

This is possibly what’s happened to your car and explains why both the DPF and check-engine light have illuminated. It’s the car’s way of telling you you need to act. While it’s generally true that vehicles like yours that do more highway kilometres than city running have fewer DPF problems, all turbo-diesel fitted with such a filter have the potential to give trouble. An electronic scan of the Triton should show whether the DPF and check-engine light are related.

The 2.5-litre turbo-diesel engine fitted to the 2010 Triton uses a toothed rubber timing-belt which requires periodic replacement. Most mechanics reckon the belt should be changed every 100,000km and because of the design of the engine, the belt that drives the engine’s balance shafts should also be replaced at the same time.

The first thing to do is to ascertain whether the suspension has sagged or not. This can be measured quite simply and the results will tell you if the springs have lost tension or not. A canopy fitted to the Triton shouldn’t really make any appreciable difference to its ride height, nor should the world’s biggest dog, but it must be factored in. Neither should towing a box trailer have any long-term effect on a vehicle rated to tow anything up to 3100kg.

If the springs have sagged, then it’s back to Mitsubishi as you have a legitimate warranty claim.

If they’re within specification and you want more rear spring, there are plenty of aftermarket companies that can supply a spring that will lift the vehicle to the height you require. Be aware, though, that there are different limits on how high you can lift a vehicle depending on what state or territory you’re in, and major modification in this department may require an engineer to sign off on the changes.

This sounds like a classic case of worn synchromesh rings inside the gearbox. These rings are designed to make smooth, easy shifts between gears but as they wear (or even break) they lose that ability and the gears become difficult to change. It’s also common for this problem to be worse on downshifts compared with upshifts which is why you can shift all the way up to fifth, but have trouble coming back down through the gears.

My money is on third-gear synchromesh being your problem. By shifting from fourth back to second and then third, you’re effectively `borrowing’ the second-gear synchromesh to soften the shift into third.

Unfortunately, the fix is a gearbox rebuild. But before that, it would be worth changing the oil in the gearbox and checking out a gearbox additive that helps with shifting feel and smoothness. If that makes a difference, great, but you may still ultimately be looking at a new or rebuilt transmission.

The other thing to know is whether the gearbox is reluctant to select reverse gear with the engine running. If it is, you might instead be dealing with a worn clutch which is much cheaper to replace.