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Cummins QSC 8.3 600HP, shutts off in idle
This topic has 0 replies, has 1 voices, and was last updated by 32 minutes ago
November 2, 2025 at 8:37 am Dear all, I have a pair of QSC 8.3 600 HP in my Charter Boat with 15400 hour and new injectrs at 14000. When fishing and I run to fishing grounds start trolling and hook up a fish and slow down to idle or neutral the STBRD side engines rpm starts varying from 620-530 and shutts off. If I crank engine start immidiately and if I keep it in nuetral or back to idle it shutts off again. Over 700rpm engine runs back normal. After a while going back to…
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160 degree thermostat
This topic has 0 replies, has 1 voices, and was last updated by 1 hour ago
November 2, 2025 at 7:26 am 6bta 5.9 315 hp, Installed a 160 degree thermostat and now wondering if it I did the right thing for my application. Fish the East Cape MX year round water temp usually mid to high 80’s. 80 to 85% of my run time is is at 1000 to 1200 rpm’s trolling. Water temp always reads 155 t0 158. When running in at 2100 rpm’s temp reaches 160. Maybe should have stuck with the old 185 thermostat? Any thoughts?
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in: General Discussion
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CIRCULATING OIL DURING TEMPORARY STORAGE
This topic has 2 replies, has 3 voices, and was last updated by
14 hours ago
October 29, 2025 at 5:34 pm I have a 2007 Cummins QSB in my boat. We use the boat mainly during the summer months accumulating about 75 hours of running time annually. However, during the off season we seldom use the boat and sit unused for months. The boat is kept in a cover slip in the Pacific Northwest where freezing issues are seldom an issue. The oil and filters are changed in the fall so it sits with fresh non-corrosive oil. I make a point every other week to run th…
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in: General Discussion
2 RepliesNovember 1, 2025 at 6:11 pm I find it hard to believe that anyone says this “Some say this occasional brief running to keep the bearings lubricated is good and beneficial”.Last Post by:
posted: 14 hours ago
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Sharing QSB 5.9 480 After Cooler Service & Pressure Testing
This topic has 0 replies, has 1 voices, and was last updated by 18 hours ago
November 1, 2025 at 2:16 pm Hello forum, After three full summer seasons May 15th thru October 15th) in 100% salt water docked in Kittery Maine and freshwater flushed (12-15 minutes each time) after each use with the 2″ main intake seacock open, I’m sharing what I found when I took the after cooler apart a couple of weeks ago. The cooler was serviced by me the “Seaboard Way” spring of 2023 with copious amounts of Alco MetaLube. Zincs after each of …
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in: Cummins Marine Engines
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Turbo Rebuild
This topic has 3 replies, has 4 voices, and was last updated by
1 day ago
October 28, 2025 at 4:59 pm I asked the shop doing some prop shaft work on my boat to replace the turbo to exhaust gasket. They said the turbo flange was rusted and needed refaced. Seemed reasonable. They pulled the turbos and sent to a shop for rebuild. Should be noted the turbos worked fine and the only issue I had was some soot escaping from the turbo-exhaust connection. Turbos made boost and engines ran fine. Engines are 2000 6CTAs w/1900hrs. Rebuild shop wants …
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in: Cummins Marine Engines
3 RepliesNovember 1, 2025 at 5:43 am Dave’s turbo in FL did mine it was around 2800 each. Very happy with his work (561) 644-6537 RG DodsonLast Post by:
posted: 1 day ago
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RPM fluctuation at idle on 6CTA8.3 480CE
This topic has 3 replies, has 4 voices, and was last updated by
October 31, 2025 at 6:04 am I have an issue with my starboard 6CTA8.3 480 CE that has confounded 4 mechanics including two visits by Cummins technicians. When in neutral at idle, the RPM fluctuate any where from 600 RPM to in excess of 900. once I put the engine in gear, the RPM stabilizes to 600. on a couple of occasions, once I start underway, the engine has actually stalled. I have also noticed that there is a slight fuel sheen in the water coming out of the exhaust. …
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in: Cummins Marine Engines
3 RepliesNovember 1, 2025 at 5:38 am Thanks to Tony’s info, I solved a similar problem. Cummins is clueless until you show them the update numbers. Then they will have to find a pigtail that connects your ECM to their computer. I removed the ECMs, about a 10 minute job, took them to Cummins in Manassas VA. They found a pigtail out of Boston. It cost about 350 per ECM, but it solved the problem. Just curious, have you checked the valve lash? I had one Cseries that the valves were ou…Last Post by:
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Zf 286 pto output
This topic has 1 reply, has 2 voices, and was last updated by
1 day ago October 30, 2025 at 11:42 am Hello everyone, I have a jet boat I’m building it has twin Cummins qsb 6.7 480 hp with zf 286 with Hamilton jets. The zf came with a pto type b 13 tooth flange for mounting a hydraulic pump but the swing dimension is too big on the drivelines leaving me with 3/8 of an inch from the bottom of hydraulic pump mount to the highest point of the yolk. I was just wondering if anyone in this group has run into an issue like this and would know a solutio…
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in: Marine Transmissions
1 ReplyNovember 1, 2025 at 3:34 am Stand back 2-3 ft and take some clear pictures of the overall area from different perspectives Seaboard Founder & PresidentLast Post by:
posted: 1 day ago
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28 Bertram with 6bta only goes 18kts at 2300rpm
This topic has 1 reply, has 2 voices, and was last updated by
2 days ago
October 31, 2025 at 1:48 am Hello, I’m new to wrenching on my diesel. My boat used to go 20-23kts at 2000rpm and now I only get 18-19kts at 2300 rpm. The port engine has intermittently blown black smoke and rpm’s and speed would reduce when under load and running at cruising speeds of 20kts at 2200ish rpm. By under load I mean pushing against a 20kt wind or carrying a 55 gallon fuel drum on deck with full fuel tank of 195 gallons. Recently my port engine started consistent…
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in: Cummins Marine Engines
1 ReplyOctober 31, 2025 at 7:19 am Focus on: Boat used to go 20-23kts at 2krpm (this is a huge range btw) Now it goes 18-19kts at 2krpm You have to understand that the boat going from 23kts at 2krpm to 18kts has *absolutely nothing* to do with the engines. *absolutely nothing*; zero, nada, zip Once you accept that, you can stop thinking about smoke, new turbos, and pump timing and start looking at vessel weight, your prop condition/pitch, hull bottom condition, etc.Last Post by:
posted: 2 days ago
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6CTA 8.3 top end work
This topic has 1 reply, has 2 voices, and was last updated by
2 days ago October 30, 2025 at 4:49 pm I have two Diamond 450 engines in my vessel. Both engines have 2500 hours and both have head gasket leaks, but only at WOT rpm’s. Based on planning for long term ownership, what level of top end engine work makes sense? What should I budget for each scope of work? Thanks, Doug Hall, Seattle
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in: Cummins Marine Engines
1 ReplyOctober 31, 2025 at 3:54 am Post some pics of the engines all around. We will want to see the area of the leaks, exhaust setup, turbos and aftercoolers. This will give us a whole lot more info so that better guidance can be given. Steve Lewis 2007 Kadey Krogen 44 WidebodyLast Post by:
posted: 2 days ago
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Manual 6 BTA 5.9 220 BHP
This topic has 0 replies, has 1 voices, and was last updated by 4 days ago
October 29, 2025 at 8:34 am Hello, I just bought a 33 fod, 6 metric ton boat in Norway with a Cummins 6BTA 5.9 220 BHP engine from 2005 with app. 800 hrs. I’m planning to sail it to Denmark (app. 300 NM) in two weeks. Does anyone have a PDF user manual and/or a service manual they will share? And can anyone share usefull information about the engine, since this is my first Cummins engine. Any good adwise? Check list befor heading out. Thanks in advance, Valdemar (Den…
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Cannot read transmission serial numbers
This topic has 12 replies, has 3 voices, and was last updated by
5 days ago
October 13, 2025 at 1:26 pm We are about to finalize the purchase of a 36′ Riviera. We had to resample the transmissions due to water in the samples and elevated iron. This was thought to be from sitting while this boat was repowered and this was condensation. Now we changed the transmission oil and put 10 hours on them and the samples came back without water but still showed elevated particle count but drastically less than the original. The issue is the serial numb…
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in: Marine Transmissions
12 RepliesOctober 27, 2025 at 2:29 pm Thank you guys for taking the time to help with this! No issues currently, hoping it stays that way.Last Post by:
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Cummins Fuel Cooler Removal Kit
This topic has 1 reply, has 2 voices, and was last updated by
6 days ago October 26, 2025 at 8:44 pm Hey all.. just watched the video on installing the fuel cooler removal kit, and I’m keen and ready to take this project on. I am wondering what connects to this ? sorry if I’m being dumb!
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in: Cummins Marine Engines
1 ReplyOctober 27, 2025 at 5:51 am That is your fuel return connection. Without seeing pictures of your current setup all I can say is that it would have originally gone to the upper fitting on the fuel cooler and then the bottom fitting of the cooler connects to the OUT side of the 3-way combo block. And then your fuel return line to the tank is also on the OUT side of the combo block. Now your goal is to have that fuel return connection that you circled going straight to yo…Last Post by:
posted: 6 days ago
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QSC 4.3 – Fuel Pressure Very High
This topic has 0 replies, has 1 voices, and was last updated by 6 days ago
October 26, 2025 at 6:52 pm Hi – I was returning from a 4 hour cruise and the boat was running very well so I decided to take it up to WOT for a couple of minutes to confirm RPM / top speed. I dont do it often but about 30 seconds into WOT the Smartcraft alarm went off with 449 Fuel Press Very High Alarm. The engine was still running perfectly, other than the alarm – perhaps just a sensor? I slowed the boat down and the alarm reset about 2 minutes later.
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Torflex coupling rubber destroyed
This topic has 4 replies, has 2 voices, and was last updated by
1 week ago October 25, 2025 at 3:24 am Hello, My port engine zf85 transmission started gradually to make noise. A loud clank-clank noise when engaging the gear and idling. Not a regular cycling noise and disappearing when reving up. It was getting worse and worse and I was afraid the ZF transmission was going bad. When disassembling it from the engine we discovered a lot of small pieces of rubber. In fact the rubber parts of the torflex coupling was totally destroyed. We never had a…
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in: Cummins Marine Engines
4 RepliesOctober 26, 2025 at 1:22 am This is a Torflex 1000 coupling Here are some pictures of the failing coupling with the reference I used to select the part and place my order. I don’t have an overview picture. Manufacture date is 2005 which is coherent with my boat building date, so this is the original coupling. My engines are QSB 425. Do you think Torflex 1000 is too weak for them for a pleasure craft usage and it explains the failure @ that low hours (but marine age is 2…Last Post by:
posted: 1 week ago
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Converting Dodge CPL1579 to a marine engine
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This topic has 32 replies, has 4 voices, and was last updated by
1 week ago September 29, 2025 at 11:37 pm I bought a CPL1579 6BT for $2200 out of a wrecked 1993 Dodge Ram with 200,000 miles. It starts easy, runs good, no smoke, no blowby. I already own everything needed to convert it to a marine engine. Exhaust manifold, turbo, heat exchanger, bellhousing, air inlet, coolant inlet/pipe etc. Almost everything except for a few gaskets. My questions are: 1- How reliable is the 160HP VE pump from the Dodge? I have an older DPA CAV pump and injectors I…
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in: Cummins Marine Engines
October 24, 2025 at 3:14 pm Take the turbo to a good hydraulic shop.. A good tech that is ‘OLDER’ can sort it out PAY HIM FOR HIS TIME Seaboard Founder & President
32 Replies
Last Post by:
posted: 1 week ago
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Strbrd Tac not working
This topic has 2 replies, has 3 voices, and was last updated by
1 week ago
September 23, 2025 at 2:32 pm Hello, My starboard tach on a 2002 6CTA 8.3 stopped working. I replaced the dual magnetic sensor and still nothing. I made jumper wires from the supply side of the port tach wires and plugged them into the starboard tach and the tach worked. I am good on the mechanical side of things but I do not have much if any experience on the electrical side. Any information is helpful in chasing this down. Thanks
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in: General Discussion
2 RepliesOctober 24, 2025 at 2:22 pm Look on the port front of engine , there might be a mechanical drive with a tach sensor, sometimes the small shaft coming off the engine can break (plastic) or the right angle drive can wear out, (must grease every 200 hrs.) or the tach sensors can go bad, let me know if you need part numbers? toolman,38 tiara,450 diamondsLast Post by:
posted: 1 week ago
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QSB 5.9: fuel cooler service
This topic has 2 replies, has 2 voices, and was last updated by
1 week ago October 21, 2025 at 6:58 am Hello Team, My boat is powered by 2 QSB 5.9 and I wonder how often the fuel coolers must be serviced in a salt water environment and how to do this properly? I’ve searched into the forum and Tony’s tips pages and did not manage to find information on the fuel cooler service interval and protocol. Hope someone can help… Cheers, Fred
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in: Cummins Marine Engines
2 RepliesOctober 23, 2025 at 7:52 pm That is crystal clear. Thanks!Last Post by:
posted: 1 week ago
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Cole Hearse 2 way alarm
This topic has 3 replies, has 3 voices, and was last updated by
1 week ago October 17, 2025 at 9:19 am What function on a 450 diamond reman 6CTA does the brown wire with blue stripe alert to?
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in: Cummins Marine Engines
3 RepliesOctober 23, 2025 at 1:56 pm This is not a standard Cummins OEM thing. This is a boatbuilder specific thing. You can see the standard Cummins harness and color code attached. Way different than what you have there. What do you have for instrumentation? What boat is this? You might need to look for others with the same boat or instrumentation package for help. Like my brother always says... "It's easy when you know how."Last Post by:
posted: 1 week ago
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Why does SmartCraft show different voltage?
This topic has 0 replies, has 1 voices, and was last updated by 1 week ago
October 22, 2025 at 7:01 am I believe that the SmartCraft system on my 2007 Cummins QSB gets power only from my start battery with no connection to my house bank. Not 100% certain of that, but I believe the start battery is its only source of power. The digital display in the SC1000 tach at each helm, the SC100 Link voltmeter gauge, and the VesselView all show 12.8 volts, but my handheld Fluke and the Victron Orion XS DC-DC charger that maintains the start battery show 13.…
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QSL9 Transmission Oil details not showing in ED-4 display
This topic has 0 replies, has 1 voices, and was last updated by 1 week ago
October 21, 2025 at 11:57 pm Hello, We have recently commissioned 2 Cummins QSL9’s as part of the restoration of a 123-year-old wooden sailing schooner in Melbourne, Australia. We have the Premier Command C units with their ED4 displays all working with the engine data, but even though the engines have the pressure and temperature sensors on the transmission oil cooler, and these are plugged into the OEM loom and plug at the rear of the engine, the ED-4 displays do no…
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Cummins QSC 8.3 600HP, shutts off in idle
