Mitsubishi Triton Problems

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.

Sludge build-up in oil is definitely an engine killer. But with a full and correct service history, this really shouldn’t happen. That it does, is possibly down to long service intervals (driven by consumer demand for less maintenance and down time) and possibly even the way the vehicle is used. If it’s worked hard (towing, for instance) in high ambient or dusty temperatures, then sludge can build up as a natural result. The way a modern turbo-diesel recirculates some of its exhaust gasses also mean soot can combine with oil vapours from the crankcase to cause a build-up of black gunge, and that’s not good either.

I’d be keen to see what the oil analysis shows. If the oil was lacking some of the additives it needs to keep a diesel engine clean, then that may show up.

If you can prove the service history to Mitsubishi’s satisfaction, I’d be asking for some kind of help in the cost of repairs. Whether or not the company plays ball is debatable, but it would definitely be worth a try with low mileage like this and documentation of correct servicing for all of its (short) life. If the vehicle is still under the factory warranty and you have a full service record for it, then it’s pretty clear you have a valid warranty claim, barring any negligence or mis-use on your part.

In many cases like this, the clutch is the culprit. The problem appears as though it’s the gearbox at fault, but the reality is that it’s the clutch not releasing properly that is preventing you shifting gears cleanly and easily. When the clutch is either worn or out of adjustment, it can remain partly engaged even when your foot is fully on the clutch pedal. When that happens, the gears can be very difficult to select.

Try this: The next time a gear becomes hard to select, turn the engine off and try it again. If the gear suddenly slips into place easily, then you’re probably looking at a worn clutch or one that is out of adjustment. Poor adjustment can be the result of low clutch fluid levels (in a vehicle with a hydraulic clutch) or a cable or linkage that is poorly adjusted. Your vehicle has a hydraulic clutch, so a leak from either the master cylinder, slave cylinder or any of the plumbing could have allowed the fluid level to drop to the point where the clutch is no longer disengaging fully. This is precisely where I’d start looking in your case.

Remember, however, that while a worn clutch might be the most likely cause, that doesn’t rule out a problem with the transmission internally or a problem in the gear selector mechanism.

It all depends on whether you have the petrol or turbo-diesel version of the Triton, Jeff. If it’s the more common turbo-diesel engine, it’s fitted with a timing chain which should last the life of the engine.

But if you have a very late-2018 build example of the Triton cab-chassis with the 2.4-litre petrol engine, then it will be fitted with a toothed timing belt which should be replaced at least every 100,000km.

The sound of air hissing on a turbocharged engine is often down to a leak in the intake trunking that takes air from the turbocharger, through the intercooler and into the engine. As this air is under pressure (from the turbo) you’re likely to hear it above the rest of the engine noise. If it’s only a small leak, you might not notice the fall-off in performance (or boost as you’ve described it) but it will only get worse as the damaged part of the trunking deteriorates further. Eventually, you’ll start to feel the leak’s effect as it allows more and more air to escape rather than being forced into the engine.

Checking the boost pressure with an accurate gauge will tell you if any boost is going AWOL, as can an electronic scan which might throw up a low-boost fault-code. But if you can hear the noise and have found the leak, replacing that section of plumbing is the logical first step. If that makes the noise go away, you’ve solved the issue.

Sometimes the leak is down to a split in the trunking, other times it can be as simple as a clamp that has been loosened by the constant pressurisation of the system every time the turbo boosts up. But it needs to be fixed as it can throw the air-fuel mixture way off target and lead to internal engine damage. If you can’t find the leak but suspect that there is one, a specialist workshop can perform what’s called an EVAP smoke test where the intake tract is filled with smoke. At the point where the (visible) smoke escapes, there’s your leak.

Mitsubishi’s manual gearboxes from around this time (and earlier) were some of the noisiest around. But usually it wasn’t anything to be concerned about. Bearing rumble and some clutch bearing noise were pretty much par for the course, but your problem sounds more like it’s associated with the gearbox’s synchromesh rings. These rings are designed to allow the gearbox to slip between ratios smoothly and silently, and any crunching noises during shifts can often be traced to worn synchromesh parts.

The good news is you won’t harm the transmission by continuing to drive it, particularly if you’re careful and take your time with the shifts you know are most likely to create a crunch. If you can live with that, fine. If not, the gearbox will need to be removed from the car and rebuilt. That will be neither cheap nor simple.