Description:
PP-3975986CN Cummins Transmission Cooler
This Seakamp Transmission Cooler is a marine-grade replacement designed for Cummins marine diesel engines used in commercial fishing vessels, workboats, sport-fishers and pleasure craft, most commonly fitted to the 5.9L, ISB, QSB family. The unit has a 3"x5" core.
The transmission cooler circulates gearbox oil through a tube-and-shell core where raw water absorbs heat, keeping marine gear oil within its specified operating range. Stable gear-oil temperature is critical for clutch-pack longevity, bearing protection and consistent shift engagement under continuous load.
Marine gear oil that overheats loses its load-carrying additives, leading to clutch slippage, premature bearing wear and seal failure. A correctly functioning transmission cooler preserves shift quality, protects the gearbox internals, and is especially important on high-torque diesel installations and prolonged trolling duty.
Manufactured to match OEM dimensions, port orientation and mounting geometry, the 3975986CN is a true direct-fit replacement for the original Cummins component. It installs without modification to existing hoses, brackets or pipework, making it suitable for planned maintenance, corrosion replacement or preventative servicing. The copper-nickel (CuNi) tube bundle gives superior resistance to seawater corrosion and electrolytic attack compared to standard copper, extending service life in tropical or high-chloride water.
Suits Cummins:
• Cummins 5.9L
• Cummins ISB
• Cummins QSB
• Other Cummins transmission cooler applications using this Seakamp form factor
Replaces / Interchangeable With:
• Cummins: 3975986CN
• 3975986 (copper variant of same part)