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    • Cummins Marine Forum Topics
    • Does high fuel consumption always indicate overprop condition?

      This topic has 2 replies, has 3 voices, and was last updated byClark Leighs 3 years ago

      April 19, 2021 at 10:50 am I have a 2008 36′ flybridge boat with twin QSB 5.9 440s. My engines will only hit 3180 RPMs at WOT and after a few seconds the temperature starts to increase. My fuel burn is at least 20% above the curve at each 200 RPM increment. I have taken good care of the boat with regular maintenance and there are no running gear or other problems. When the boat was new it would run 3460 RPM at WOT. A couple years ago I installed my spare set of prop…

      Started by: Jack Wallace in: General Discussion

      2 Replies
      April 29, 2021 at 10:13 am I agree with Steve Lewis that you are most likely over propped as it is now. THe temp rise would also indicate to me that it is time for you to start looking into a cooling system service. There are many areas to go after so rather than a lot of writing I offer my tome below. Read through it. If there are questions then repost.

      Last Post by: Clark Leighs posted: 3 years ago

    • Seawater pump belt removal on qsb5.9

      This topic has 3 replies, has 4 voices, and was last updated byScott Lambert 3 years ago

      May 26, 2018 at 10:51 am I have twin qsb5.9 440s on my boat. The engines have the newer seawater pump belt configuration but my manual only shows the older belt setup with an idler pulley. How do I remove and reinstall the belt if I canā€™t lessen it? Do I just get it off a little and then advance the engine to walk it off the pulley? Where do I put my wrench to advance the engine?

      Started by: Jack Wallace in: Cummins Marine Engines

      3 Replies
      November 17, 2020 at 12:19 am Isn’t the engine being rotated backwards in that video?

      Last Post by: Scott Lambert posted: 3 years ago

    • SMX leak and other issues

      This topic has 2 replies, has 3 voices, and was last updated byTony Athens 4 years ago

      April 10, 2020 at 10:55 am I have a 36′ boat with twin Cummins QSB 5.9 440s. I replaced both Sherwood pumps with SMX pumps several years ago. I noticed water leaking from the weep holes on the port engine’s pump last season and when I looked closely I found a lot of rust under the fuel pump and around the lip at the base of the block where the oil pan attaches. I also noticed what looks like rusty water running under the engine and the small amount of water in…

      Started by: Jack Wallace in: Cummins Marine Engines

      2 Replies
      April 10, 2020 at 4:38 pm Jack, Get back a few feet and take some pics of the entire engine and that area.. If the pump is leaking seawater and it’s one of ours, send it in and we’ll fix it au-gratis–Just shipping applies. As to the rest, you really need to do daily engine room checks as that is what a prudent owner does.. What I have looking at took MONTHS of dripping to do this.. Get lt all cleaned up and keep that area “oily or greasy” t…

      Last Post by: Tony Athens posted: 4 years ago

    • Raw Water Intake Covers

      This topic has 2 replies, has 3 voices, and was last updated bydonald roth 5 years ago

      May 21, 2018 at 10:02 am I bought my 36′ Norstar Flybridge new in 2008. It had twin QSB 5.9 440s. When they first put it in the water, Cummins came out to test the engine systems. After testing, the Cummins rep had the boat manufacturer pull the boat out and remove the starboard engine’s wedge-shaped strainer (raw water intake cover) from the outside of the hull. Everything has worked fine for 900+ hours on the engines and I have had just a little more seawe…

      Started by: Jack Wallace in: General Discussion

      2 Replies
      June 27, 2018 at 11:55 pm Thanks, Rob, I never thought about electrolysis affecting the scoop, but mine recently fell off when underway. I guess the SS screws let go. Theyā€™ll be silicone bronze next time! Also as a side effect, the water flow alarm now occasionally chirps after hitting a large swell, irritating at times but it is reassuring to know that it is working.

      Last Post by: donald roth posted: 5 years ago

    • Raw Water Leak

      This topic has 1 reply, has 2 voices, and was last updated byTony Athens 7 years ago

      April 21, 2017 at 3:03 pm I have twin QSB 5.9 440s on my 2008 36′ Norstar with about 1,000 hours. I have been doing most of the engine maintenance myself. I have followed the manual but have added additional work on theĀ sea water side. Last year I pulled the aftercoolers and cleaned the cores per recommendations on this site. The aftercoolers were pretty clean with very little corrosion. After reinstalling the aftercoolers I could not stop a raw water leak on the i…

      Started by: Jack Wallace in: Cummins Marine Engines

      1 Reply
      April 22, 2017 at 6:29 am Pictures of the leak and of the entire /or overall installation would really help.. Just like you can see what is going on, we need to also “see” it.. Ā  Also, what seems confusing to me it that you said you serviced the aftercoolers last year, but then you sent out the gear coolers to have them cleaned. Ā Cleaning the aftercoolers is way more challenging than cleaning a gear cooler? What do you mean by “flushing the aftercooler?…

      Last Post by: Tony Athens posted: 7 years ago

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