Blow by

I'm assuming this is a twin turbo CAT?

If it is, these engine will huff a considerable amount of blow by while idling. The engine rings are designed to work against cylinder pressure and seal the blow by off under load. CAT has had many complaints about excessive blow by on these engines. CAT also came out with a catch can/oil separator arrangement to install on the crankcase vent tube to catch the excessive oil and return it to the oil pan.

My acert puffs like a locomotive and sprays oil underneath my truck, but only burns a gal of oil every 5,000 miles.

 

I think the catch can was more an emissions thing since crankcase vapours started counting against an engine at around that time.

 

It could be your air compressor or turbos. Disconnect the the air discharge line and see if puffing goes away. You can unbolt the the oil drain line one at a time from the the turbos and place drain lines or fabricated drain lines into bucket (since it will make a mess) and see if puffing goes away.