Product Description
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)
| Year Range | Engine | Chassis |
|---|---|---|
| 2003–2005 | Ram 5.9L ISB (24V Common-Rail) | Ram 2500/3500 |
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.
Compatibility Notes:
- Not for 2006–2007 5.9L trucks; those require the later non-serviceable valve cover assembly to address the CCV element.
- Common companion parts on 2003–2005: breather vent tube 5265108 and breather oil drain tube 5265106.
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.
