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Joe, Technician
Category: Heavy Equipment
Satisfied Customers: 812
Experience:  20-plus Yrs. Master Mechanic , Specializing in Cummins and Cat midrange , RV's and Commercial bus.
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what causes an N14 cummins engine to blow oil from breathe

Customer Question

what causes an N14 cummins engine to blow oil from breathertube
Submitted: 6 years ago.
Category: Heavy Equipment
Expert:  Joe replied 6 years ago.
Hello , my name is Joe

I have read your question and will do my best to help.

There are 3 main factors that can result in excessive blowby in your engine: Internal engine damage , a malfunctioning or defective air compressor , or a malfunctioning or defective turbocharger.

There may have been dirt or dust entering the engine from a small gap in the air filter boot or tubing.
You can visually inspect for any of the following:
  1. Loose intake clamps between the air filter housing and the turbocharger inlet.
  2. Worn, loose, or broken air housing latches/clamping hardware.
  3. Loose or poor fitting connection at the turbocharger inlet.
  4. Collapsed or buckled intake piping.
  5. Incorrect filter installed by customer or OEM. Contact Cummins Inc. if there is a question about proper filter installation.
  6. Poor seal at filter (incorrectly installed, damaged filter or housing, worn latches , etc.
The turbo and the air compressor can also contribute to excessive blowby and oil discharge from the vent tube...Proper diagnosis would require specialized equipment.

A special blowby measurement apparatus is normally used to measure engine blowby with a type of pressure gage called a manometer.
Once a blowby measurement has been taken , then the air compressor and the turbocharger can be isolated - one at a time.
By isolating the air compressor and the turbo , it can be determined if either component is a major contributor to the amount of blowby.

Please let me know if you still have any concerns.