Lube Filtration Overview
Diesel Engine Lube Filtration Systems The difference between the various lube filter configurations can be confusing. There are three common
filtration approaches. Full-Flow Filtration
Two-stage Filtration A two-stage filter design attempts to combine the features of both a full-flow and by-pass filter. The two-in-one design significantly increases restriction, causing shorter filter life and decreased cold flow performance. Poor cold flow performance starves the engine of oil during start up, leaving the engine temporarily unprotected. This may lead to increased engine wear that could result in premature repairs or even engine replacement.
Full flow-filters receive near 100% of the regulated flow in an engine lube system. Full-flow filters provide essential engine protection for maximum cold flow performance and filter life. Most lube filters available today are full flow. By-pass (Secondary) Filtration By-pass filtration is when a small portion of the system’s oil flow (usually 5-10%) is diverted back to the sump or oil pan before reaching the primary filter. A by-pass filter captures smaller particles than the full-flow filter. Because of the increased efficiency of a by-pass filter, they are more restrictive. To optimize restriction, a by-pass filter should be located in a separate flow path, as illustrated on the right.
TYPICAL DIESEL ENGINE LUBE CIRCUIT
Engine components to be lubricated
FULL-FLOW LUBE FILTER
BY-PASS LUBE FILTER
High Pressure Relief Valv e (135 psi / 931 kPa)
Pump
Return Flows to Sump
Sump or Oil Pan
Engine Liquid Filtration • 31
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