Mitsubishi Triton Diesel 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.

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.

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.

It sounds like it could be the fuel supply; check the fuel filter, fuel pressure, and the injectors. It’s a common-rail diesel engine and they are prone to injector wear.

The dealer is giving you the brush-off. Take it to another mechanic and get a second opinion.

I reckon your mechanic is on the money with the injectors. Worn injectors are a common problem on common-rail diesels; it's something that affects most brands

I would be looking at the injectors first. Worn injectors are common in modern common-rail diesel engines; it could also be a sticking injector. You could also check the low and high-pressure fuel systems.

I would be looking at the fuel supply, the filters, fuel pump, and the fuel itself. If the performance generally has dropped off I would also be looking at the turbocharger.

I would flush the fuel system out to clean out any contamination, and change the fuel filters.

I would agree with the dealer's diagnosis of carbon build-up and cleaning it will probably fix it.