2018 Mitsubishi Triton Pricing and Specs

Blow-by is a normal part of engine operation, particularly turbocharged engines where the combustion chamber pressures can be extremely high, forcing gasses past the piston rings and into the crankcase. Excess blow-by, however, suggests that there’s perhaps an overboost problem, wear in the engine or that the ventilation system designed into the emissions controls of the engine is not working properly.

The crankcase ventilation valve would be a good place to start checking as these can become very dirty and even clogged over time in a diesel engine, and a compression test of the engine might tell you more as well. The first thing to do is find another vehicle of the exact same make and model and see if it, too, has a similar level of blow-by in evidence. From there, you can decide which way to go, but either way, a good diesel mechanic should be able to identify the problem accurately.

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.

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.