The vacuum pump discharges internally into the engine crankcase; so along with piston blowby, there is always going to be some positive pressure potential within the engine if not removed properly.
Some members in the past on this forum reported oil seal leakage and / or rear main seal blowout along with all the visible smoke observed with the EHM at idle which created a lot of discussion on the subject and the merits of having the EHM.
But I think GDE in their 2014 post stated it best:
GreenDieselEngineering wrote:
The VM engine specs are very similar to other OEMs:
8.4 CRANKCASE VENTILATION
The engine is supplied with an oil separator incorporated in the cylinder head cover and the duct must be connected to the main inlet duct, between air cleaner and turbocharger compressor inlet.
The crankcase must always be kept under negative pressures. The depression however should never exceed 20 mbar. To meet this target it is often necessary to use a vacuum control valve.
The blow-by from the engine should never exceed 15 liters/min per cylinder.
Any vehicle inlet system, including air cleaner, ducts, intercooler and crankcase ventilation, once in a fully design intent configuration will be evaluated on the test bench by VM for a final approval.
If I was still currently running an EHM, I would be rethinking the logic behind that modification and the consequences or ramifications that it may entail.....
An EHM will not supply any negative pressures in a crankcase! In the end, the consensus of the group was an EHM mod is not good!
Bottom line: It is your vehicle, if you want to continue running an EHM, that is your prerogative, no one will beat you up doing so!
We are each our own Warranty providers and must make the best informed decisions possible when it comes to modifications and / or the consequences thereof...
_________________
Supporting Vendor and Moderator of LOST05 Jeep Liberty CRD Limited
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