Mitsubishi Triton Engine Problems

A leaking rocker cover gasket won’t cause the engine to stop unless it somehow manages to allow too much lubricating oil to escape the engine (which, it potentially could over time). But it still needs to be fixed, because technically the car is unroadworthy with an oil leak and various bits of the car will be getting coated with the oil as it leaks out. Rubber suspension bushes, in particular, are intolerant of contact with oil and will degrade as a result. You might also find the leak is dumping oil on your tyres or the ground in front of them. So it needs to be fixed sooner rather than later.

As for the original diagnosis of your car needing a new engine, I’d be giving that workshop a wide berth as the mechanic in question might be either incompetent or attempting to rip you off. Or both. Your decision to seek a second opinion was a good one and should be standard practice.

If the engine is running well, but the car won’t move in gear when you take your foot off the clutch, it’s very likely that your clutch has failed. The clutch is responsible for transferring power from the engine to the gearbox and, if it wears out, it can no longer do so and the vehicle will just sit there and not move even when you take your foot off the clutch pedal and the car is in gear.

You noted that the car had previously seemed to lose power, but this was more likely to be the start of the clutch failing and not transferring all the power it should have been. Eventually, though, the failure became total and no power is getting through to the gearbox (and, therefore, the wheels).

A new clutch is the likely fix but make sure to check the flywheel for damage and wear while the car is apart.

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.

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.

You say you’ve checked the basics, but it’s worth taking a close look at electrical connections that form the basis of the car’s ignition system. Are all the plug leads properly connected? Is the high-tension lead form the distributor to the coil secure and the coil wires correctly hooked up? Any fault with these things can cause a no-start situation.

The other prime suspect in a car of this age would be the electric fuel pump. These usually live inside the fuel tank and have a very finite lifespan. If you can’t hear the pump humming when you turn on the ignition, it’s probably dead and could well be the cause of your problem.

Beyond that, there are a lot of things that could be the cause here, but many of them are cheap and simple to fix once you’ve diagnosed the issue. It’s worth having the car checked over in case it is something really simple (and inexpensive). The Mitsubishi V6 is pretty good unit and if you’re happy with the rest of the vehicle (and it sounds like you are) then fixing the problem and squeezing every last kilometre out of the thing is the way to go.

The confounding element, of course, is that fifth gear is getting hard to engage. This could be a simple linkage adjustment problem, low clutch fluid or it could be a worn out clutch. Again, though, a proper diagnosis should be your next step before deciding whether to repair or sell and move on.

This sounds like a fairly serious failure somewhere in the engine that is pressurising the cooling system (and the coolant overflow bottle) and draining the engine of the coolant it needs (which is why the overheating light is on). This can be due to a blown cylinder head gasket or some other failure within the engine that is allowing combustion pressure into the cooling system.

The best advice is to not drive the vehicle any farther and get it to a workshop who can diagnose the problem properly, rather than just guessing about the cause. Don’t forget, though, that your Triton, provided it’s been serviced properly, should still be covered by Mitsubishi’s factory warranty.

The MQ Triton doesn’t seem any better or worse than its rivals in this department. But, like other makes and models, there’s a healthy aftermarket supply of replacement intercoolers and the pipework that feeds them, so it’s definitely not an unknown problem.

But your experience is exceptional. Were all five vehicles bought brand-new at the same time? If so, they’re all likely to be from the same production run which could explain a faulty batch of hoses.

Mitsubishi quotes a combined average of 10.9 L/100 km for the 2.4-litre dual-cab Triton. Around town they claim 13.9 L/100 km and on the highway 9.1 L/100 km. It’s similar to other dual-cab utes.

You don’t tell us why your ute needs a new head at just 134,000 km, so it’s hard to comment. If nothing untoward has happened to cause the problem, like overheating, then you could try and convince Mitsubishi to cover the cost of repairs, but unless you have a full history that clearly points to a manufacturing fault I think you would struggle to justify a claim.

There wasn’t a recall for this problem on this model, but there was a service bulletin (like a recall but for a non-safety related issue). The problem was the same as yours; examples of this diesel engine were overheating. The cause was deemed to be a loss of coolant and was related to poor cylinder-head gasket sealing. In turn, that was deemed to be the result of a too-rough metal surface on the cylinder block where it joined the cylinder head and sandwiched the gasket.

Mitsubishi introduced measures such as a different coolant concentration, a different radiator cap and an ECU that gave more warning to the driver. But none of these things actually fixed the issue with the head gasket and the metal surfaces. In fact, it wasn’t until 2014 production that Mitsubishi changed the machining process on the production line to give a smoother head-gasket sealing surface which solved the problem for good.

It seems that some engines had problems while other simply did not. Hard use such as towing heavy loads or driving at sustained high speeds made the problem more likely to surface.