Cummins 3957987 — Genuine Crankcase Breather (CCV) Filter for ISB 5.9L

MPN: 3957987  |  Also Known As: crankcase breather filter, CCV filter, breather housing (industrial catalogs)

Genuine Cummins CCV (crankcase ventilation) filter that installs on top of the valve cover to control blow-by vapors on 2003–2005 5.9L ISB common-rail engines. Includes new O-ring for a leak-free seal. Replacing a clogged CCV filter helps reduce oil leaks, seals blowing out, and oil carryover into the turbo.

Features & Benefits

• OE filtration media to separate oil mist from crankcase vapors.
• Direct-fit drop-in on the valve cover for fast service.
• Prevents excess crankcase pressure that can push out seals and force oil into the intake tract.
• Includes new O-ring to ensure proper sealing at install.
• Backed by Cummins quality and fitment confidence.

Verified Fitment (Automotive)

Industrial/Off-Highway: Listed as a breather housing for certain ISC/ISL/L9 platforms in heavy-duty catalogs; verify by ESN before ordering for non-automotive use.

Specifications

• Type: Crankcase breather (CCV) filter
• OE Part Number: 3957987
• Includes: New O-ring
• Location: Top of valve cover
• Service Interval: Inspect regularly; replace if saturated/restricted or per maintenance schedule

Often Paired With

• Breather Vent Tube (2003–2005): 5265108
• Breather Oil Drain Tube (2003–2005): 5265106
• Fresh air filter / oil change: good time to reset maintenance baseline

What’s In The Box

• (1) Genuine Cummins CCV Filter (3957987)
• (1) New O-ring

Installation Tips

• Remove the valve cover CCV cap, lift out the old element, clean seating surfaces, and install the new filter with the included O-ring.
• Verify breather hoses/tubes are unobstructed; replace brittle or oil-swollen hoses.
• After installation, check for leaks and monitor crankcase pressure/idle quality.

FAQ

WILL THIS FIT MY 2003–2005 5.9L CUMMINS RAM?

Yes—3957987 is the OE CCV (crankcase breather) filter for 2003–2005 Ram 2500/3500 5.9L ISB common-rail (confirm by VIN/ESN).

DOES IT INCLUDE THE O-RING?

Yes—this kit includes a new O-ring for proper sealing at the valve cover.

WHAT ABOUT 2006–2007 5.9L TRUCKS?

Those model years use a non-serviceable design. Cummins guidance is to replace the complete valve cover assembly rather than just a filter element.

IS THIS THE SAME AS THE “BREATHER HOUSING” I SEE IN HEAVY-DUTY CATALOGS?

Many industrial listings call 3957987 a “breather housing.” For Ram trucks (’03–’05 5.9L), it functions as the serviceable CCV filter element on the valve cover. For non-automotive engines, verify by ESN.

WHAT SYMPTOMS POINT TO A CLOGGED CCV FILTER?

Excess crankcase pressure (oil leaks, dipstick blow-by), oil found in the intake/turbo inlet, and oily residue around the breather cap are common indicators.