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Old Nov 6th, 2021, 17:22   #13
Zebster
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Originally Posted by OldEngineer View Post
It's the diesel wiping off the oil protection on the cylinders. It attacks this oil coating and then flows past the piston rings into the sump.

The diluted oil is also not providing sufficient protection in later stops. So cycle of wear is started that ruins the engine.

If you are offered a low mileage diesel car you need to walk away. Unless the low mileage is made up of long runs with no cold stop/starts in between.

And, of course, this problem is nothing to do with Volvo quality. The replacement Peugeot will go the same way if it suffers cold stops (which a Hybrid is more likely to do). Hopefully the new one is a petrol?
But why would diesel be left in the cylinder to run down into the sump? The fuel injection would cease immediately when the vehicle 'ignition' was switched off, even though the engine would then still undertake a few revolutions due to momentum that would clear the cylinders. In any case, even if the last spurt from an injector was left in one cylinder then it'd only be a fraction of a CC, so it seems unlikely that this tiny amount could cause the sump volume to increase by 0.5L (e.g. the alarm level) even after time.

Surely such a significant amount of diesel being accumulated in the sump is far likely to be caused by one (or more) leaking injectors, potentially allowing the entire pressurised volume in the rail to be discharged?
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