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    • Cummins Marine Forum Topics
    • QSB 6.7 Heat exchanger corrosion

      This topic has 12 replies, has 5 voices, and was last updated byRob Schepis 4 years ago

      April 19, 2019 at 5:19 am At 2000 hour service heat exchanger badly corroded. Radiator shop supporting large diesel shop could not get core out. Have owned boat for 2 years. Zincs in heat exchanger have shown little wear during that time. Corrosion and little zinc wear seem inconsistent. Thanks to previous advice from Seaboard, I learned the QSB 6.7 after cooler had plastic caps. (Discovered when unable to remove zincs.) When changing out plastic after cooler cap…

      Started by: ciscokid69 in: Cummins Marine Engines

      12 Replies
      May 24, 2019 at 5:30 am That unusual wear in the pictured zinc could be the result of erosion due to it’s location in the water flow and small pcs of debris (old zinc pcs, sand, etc) that have settled down and accumulated around it that is continually blasting the zinc with the water flow. Next time you remove it, stick your pinky in the hole and feel around it and see if you feel loose gritty material surrounding the zinc port.

      Last Post by: Rob Schepis posted: 4 years ago

    • Oil in expansion tank

      This topic has 5 replies, has 4 voices, and was last updated byTony Athens 4 years ago

      May 16, 2019 at 11:49 am Picked up debris on intake for raw water and cooked the impeller. Engine temp got to 218 degrees before shutting down. Fixed raw water side. Discovered engine oil in expansion tank. Engine oil is clean. Down a quart from previous day check. QSB 6.7 Called for help but would welcome input. I am not very knowledgeable but current assumption is an engine oil cooler is pushing oil into coolant. Thanks

      Started by: ciscokid69 in: Cummins Marine Engines

      5 Replies
      May 21, 2019 at 5:48 am I’d be washing out the coolant system and do a 1st class pressure check at 25-30 PSI with the system empty. I have not seen a failed engine OC on either a QSB 5.9 or 6.7.. How much oil was in the coolant.. A quart would be super obvious.. Some “scum” is normal on old coolant. Tony

      Last Post by: Tony Athens posted: 4 years ago

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