V9x engine with white smoke

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Sep 4, 2023
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Hello, I have an Infiniti Q70 with a V9X diesel engine and I have encountered some problems. Maybe you can help me. When I bought the car, I drove 300 kilometers on the highway, but the next day the malfunction indicator light came on, showing that the DPF was blocked. At that time, I didn't pay much attention to it because driving on the highway can clear the DPF. However, for the next three months, the car has been lacking power. It felt like pressing the accelerator hard didn't accelerate as quickly as lightly pressing it. Eventually, the car started emitting black smoke while driving, and the speed remained at around 30 miles per hour. The repair shop said it was a problem with the fuel injectors and replaced 6 of them. Until now, there haven't been any major issues.

Now, the current problems are that the engine oil keeps decreasing, and I feel like there's no oil leakage, but I can see oil inside the intercooler rubber hose. Also, when I press the accelerator in sport mode, a lot of white smoke comes out.

Can you please advise on how to solve these two problems?
First up: welcome aboard.

Second: the oil inside the intercooler rubber hose is NORMAL. It's supposed to be there. Combustion gases do seep past the piston rings, the oil in the sump is heated up - some turns to vapour - and is pushed out the PCV (Positive Crankcase Ventilation) at the top of the rear of the motor. This then moves through a rubber hose to the air intake just in front of the turbocharger. The oil then passes into the combustion chamber where it is burnt and expelled through the exhaust. This is how it's supposed to work.

You can use that oil to see how good your turbocharger is - if there's metallic flakes in the oil, your turbo is worn.

You can catch some of that oil with a "catch can" - basically a container that sits in the pipe from the PCV to the intake and allows the oil to condense within it rather than sending it through the intercooler and into the manifold for combustion.

Now the real problems.

High oil consumption isn't a good thing but could be happening in numerous places - finding the exact place will be a bit of a process. Sometimes a turbo will leak out its turbine (hot side) bearing and the oil will mostly combust in the exhaust. This usually happens when the bearings start to let go and you might be able to determine this by trying to wiggle the main shaft if you can get to it.

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