Using oil...

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Worn seals inside the turbo can also cause excessive crankcase pressure. If you are going to try and determine the root cause of this issue yourself, along with checking the pressure with the compressor on (pumping) and off, take the time to check the turbo out as well. This can be done in a couple different ways, 1. A smoke machine attached to it (compressor side) will allow the smoke into the crankcase if the seals are going bad or, 2. Pull the turbo oil drain line and place it in a bucket and see if there are bubbles coming out, if so, that is the pressure coming from the compressor side finding its way into the crankcase.