Description:
PP-3975986 CN KIT Cummins Marine Transmission / Gear Oil Cooler with Mounts
The PP-3975986 CN Cummins Marine Transmission / Gear Oil Cooler is a heavy-duty copper-nickel shell-and-tube oil cooler engineered for Cummins QSB-series marine diesel engines, including the widely used QSB 6.7�L platform.
This oil cooler dissipates heat from marine gearbox oil by circulating oil through the internal tube bundle while raw seawater flows through the outer shell. Maintaining correct transmission oil temperature is critical for protecting clutch packs, thrust bearings, seals, and gear sets—particularly during extended cruising, tight manoeuvring, towing, or high-load operation.
The CN (copper-nickel) construction provides excellent resistance to salt-water corrosion, dezincification, and electrolysis, offering a significant durability upgrade over traditional copper-brass coolers. Integrated sacrificial pencil zinc anodes provide additional protection against galvanic corrosion and help extend service life in harsh marine environments.
Manufactured to meet OEM dimensional, flow, and pressure specifications, the 3975986CN is a direct-fit replacement for the original Cummins 3975986 oil cooler. It installs without modification to hose routing, oil fittings, or mounting arrangements
Suits Cummins Marine:
• QSB 6.7�L
• QSB 5.9�L (selected configurations)
• QSC 8.3�L (application-dependent)
• Cummins marine engines fitted with remote marine transmission / gearbox oil cooling
• Commonly paired with ZF, Twin Disc, Borg Warner, and similar marine gearboxes (installation-specific)
Replaces
• Cummins: 3975986