Replacing the Transmission Oil Cooler with One That Has Zincs

By Robert Claycomb — Owner of Deneige, 32-276, Santa Barbara, CA

A friend here in our harbor has a 2005 32 NT and I have a 2006 32 NT. Both boats have Cummins (6 BTA). Last month my friend was out 25 miles fishing, when he noticed an oil sheen spreading out behind his boat. As it turns out, Cummins uses a transmission oil cooler that does not utilize zincs unlike the engine heat exchanger. My friend quickly discovered that his transmission cooler failed. (He was however, able to save his transmission). What is happening is that salt water sits in the transmission cooler when at rest, slowly eating away at the internal cooling tubes.   

After learning what happened to my friend, I contacted Seaboard Marine located in Oxnard, CA:   

They recommended the oil cooler that they sell which has two zincs (about $400).  I bought one and installed it along with a new water hose at each end.   I thought why wait until I was 25 miles out for mine to go south? I also installed a VDO transmission pressure gauge.  Seaboard Marins website has information on this gauge.


Factory Installed Transmission Oil Cooler Replacement Cooler Painted (note zincs)
New Cooler Installed New Cooler Installed
Installed Pressure Gauge 90° Steel Elbow for Pressure Gauge



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