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post #8 of Old 07-09-2013
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Re: M25 what is this and where does the hose go?

Sorry to be a PITA but to have this pipe going directly from the rocker cover into the inlet manifold is perhaps not that wise. These systems are called Positive Crankcase Ventilation (PCV) systems and are designed with special valves that prevent the vacuum from the manifold drawing oil from the rocker cover (similar to the vented loop in the raw water cooling system)

A diesel engine is not like a gasoline engine - it does not have a throttle plate in the manifold to control engine RPM. RPM is controlled by the volume of fuel that is injected. But if the engine starts to draw oil from the rocker cover into the inlet manifold, the engine will start enjoying the oil and will not need diesel to run on. Granted, manifold vacuum on a diesel is not as high as a gasoline engine but when the revs get up there the vacuum may be enough to draw oil from the rocker cover.

And if it does you may end up with a run-away engine. These can be character-building but are generally not recommended.

I am not a diesel specialist so the opinion above is offered reservedly. Just be sure you know what you're setting up. If the original system was a pipe hanging down the side of the engine, chances are it was never set up to be a PCV system.

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