M11 Series Engines – Crankcase Gases (Blowby) Excessive

Symptom Tree  t027

This is symptom tree t027
Cause Correction

Crankcase ventilation system is plugged

Check and clean the crankcase breather and vent tube. Refer to Procedure 003-002.


Centrifugal bypass filter is malfunctioning

Disconnect and plug the air supply line to the filter. Check for blowby again. If blowby is within specifications, repair the filter. Refer to Procedure 007-012 and the OEM service manual.


Turbocharger oil seal is leaking

Check the turbocharger compressor and turbine seals. Refer to Procedures 010-040 and 010-049.


Air compressor is malfunctioning

Isolate the air compressor by disconnecting the air inlet and outlet lines. Refer to the Holset® Air Compressor Master Repair Manual, Bulletin 3666121. Check blowby. If blowby is within specifications, rebuild or replace the air compressor.


Rocker lever housing or rocker lever housing gasket is leaking intake air into the crankcase

Inspect the rocker lever housing for cracks. Inspect the gasket for tears and breaks. Inspect the gasket sealing surface for scratches and cracks. Refer to Procedure 003-013.


Cylinder head valve guides are excessively worn

Check the valve guides for wear. Replace the cylinder head if necessary. Refer to Procedure 002-004.


Cylinder liner, pistons, or piston rings are worn or damaged

Check the pistons, piston rings, and cylinder liner. Refer to Procedures 001-043, 001-047, and 001-028.

Last Modified:  02-Feb-2007