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- Cummins Marine Forum Topics
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Remove fuel cooler – QSM-11
This topic has 1 reply, has 2 voices, and was last updated by
1 month ago November 20, 2025 at 3:52 pm Following up on a previous question – I want to remove my fuel cooler on a QSM-11 dry exhaust. Is it as simple as disconnecting the fuel hoses from the cooler, and joining them together with a male-male adapter for the hose size? Or is it more complex?
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in: Cummins Marine Engines
1 ReplyNovember 21, 2025 at 6:34 pm Yes, it is that simple. Seaboard Founder & PresidentLast Post by:
posted: 1 month ago
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Wiring direct to battery or incorrect
This topic has 6 replies, has 4 voices, and was last updated by
1 month ago
April 3, 2022 at 11:56 am Yet again another question everyone. These wires are wired directly to batteries. <br /><br />talking about the white abs black wires 1) what are they for 2) do they need constant power or can I run to my panel on my blue seas bar
Started by:
in: Cummins Marine Engines
6 RepliesNovember 20, 2025 at 3:54 pm I understand there’s these power studs on the ECM that need good solid voltage/current under all conditions and that Cummins calls them ” unswitched.” I can understand that maybe they don’t want these terminals to only be energized when the ignition is energized but I’m not very comfortable with having these energized without the possibility of disconnect with the main battery switch. Besides the fact that the ABYC …Last Post by:
posted: 1 month ago
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Oil Temps QSB 380
This topic has 6 replies, has 4 voices, and was last updated by
1 month ago
November 18, 2025 at 8:06 pm Hi all, just took a sea trial with in a tug we’re very interested in. Oil temps were consistently 50 -70 degrees above coolant temps peaking at 261 during a brief full throttle test. Is this normal? Coolant crept up towards 190 at full throttle. Attached a screenshot of the Garmin engine data.
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in: Cummins Marine Engines
6 RepliesNovember 20, 2025 at 1:38 pm Thanks, that’s interesting. I’ll have to investigate that if we end up with the boat.Last Post by:
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Exhaust/turbo bolt broken – 6CTA
This topic has 7 replies, has 4 voices, and was last updated by
1 month ago January 13, 2020 at 1:37 pm Hi All, I want to pull my port exhaust elbow just to check for issues, but one of the bolt heads has corroded and sheared off. The other bolt heads are also corroded to a point that a regular wrench is ineffective. (Seawater leak, since repaired.) There is no evidence of any exhaust leaks. What are my risks running the boat as is? Access is horrible, and it looks like the next option is grinder/cutoff wheel, and space for this is very tight …
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in: Cummins Marine Engines
7 RepliesNovember 20, 2025 at 12:17 pm That’s not a spacer, that is the mounting flange on the exhaust riser. Here’s a couple examples. If you pull the turbo yes you need to drop the coolant. Pull the exhaust riser off the turbo so you can inspect the turbo and check the mating surfaces and deal with the fasteners. Block sand the turbo exhaust face (and flange if needed) and reinstall with this gasket: https://www.sbmar.com/product/cummins-graphite-turbo-charger-to-e…Last Post by:
posted: 1 month ago
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Grid Heater Bolt Failure Common with Cummins Engines
This topic has 1 reply, has 2 voices, and was last updated by
1 month ago November 5, 2025 at 1:47 pm Hello all, I was just curious if the dreaded “Grid Heater Bolt Failure” problem, common with Cummins 6.7 truck engines, is also a possibility with Cummins QSB 5.9 marine engines? Has anybody ever come across this issue? Thanks, Jesse
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in: Cummins Marine Engines
1 ReplyNovember 19, 2025 at 7:11 pm Simple answer is NO–Completely different design on the marine engines. Seaboard Founder & PresidentLast Post by:
posted: 1 month ago
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Twin Disc 5082
This topic has 1 reply, has 2 voices, and was last updated by
1 month ago November 18, 2025 at 4:13 pm I have my steering driven by the live PTO from my twin disc 5082. I’m am currently around 10k hours on the engine/reverse gear. In the last 2 weeks when I put the motor in neutral I lose the power steering. As soon as I place it in gear the steering is smooth/ normal but sometimes chatters like its rebuilding the pressure. The oil level is good and the pressure is around 362psi which is where it always has been. After talking with my mechanic th…
Started by:
in: General Discussion
1 ReplyNovember 19, 2025 at 6:33 pm Your issue is quite common, but it is way too complicated to put into words, and frankly above my pay grade. The expert on your exact issue lives in Kentucky, and if you send me your phone number (tony@sbmar.com) I call you to discuss and then put you in touch with him.. Seaboard Founder & PresidentLast Post by:
posted: 1 month ago
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Duty Cycle Chart QSC 8.3 490
This topic has 3 replies, has 2 voices, and was last updated by
1 month ago
November 17, 2025 at 5:49 pm Tony recommended that I create a duty cycle chart a while back and I finally took the time to do so after doing an engine rebuild and full refit on the boat. Here is my engine data and the chart. My target cruise is 2200. Let me know what you think of these numbers. This is also a “fun” exercise to make over the winter if you are bored.
Started by:
in: Cummins Marine Engines
3 RepliesNovember 19, 2025 at 9:14 am Tony, based on the information provided, you can see that the boat becomes most economical at 2300-2400 RPM. 2300 RPM being 17.5 GPH 68% Load 2350 RPM being 18.5 GPH 72% Load 2400 RPM being 19.4 GPH 75% Load I know we talked before and you were recommending 400 off of max rated RPM per cummins for the 490 HO application in Pleasure Craft boats. At 2200 RPM being 16.3 GPH 62% Load, do you still recommend 2200 as being the cruising rpm for this hu…Last Post by:
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6bta fuel solenoid frustration
This topic has 3 replies, has 3 voices, and was last updated by
1 month ago
November 7, 2025 at 1:58 pm Ok I’ve posted before and now solved the majority of those issues BUT after 2 hours of tiny adjustments still cannot get the fuel solenoid to let the engine start. Here’s what I’ve done so far. Bought two replacements Mayspare solenoid part # 3935649. Bench tested both pull in then hold. Plugged both in the engine wire connector and confirming they pull in then hold based on the engine on switch. Manually moved the lever to start position o…
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in: Cummins Marine Engines
3 RepliesNovember 17, 2025 at 1:19 pm Turned out the real issue was the length of the rod on the bottom that attaches to the lever. I had to extend it with a coupler by 1/4” to insure it would pull in and lock. PaulLast Post by:
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MOTA Aftercooler 480CE
This topic has 0 replies, has 1 voices, and was last updated by 1 month ago
November 17, 2025 at 7:09 am Removed my MOTA aftercoolers and was in the process of changing seals after 2 years of use. 2003 480CE engine configuration. There are brass or bronze plates used on the topside of the cooler which form a sealing surface between the upper and lower gaskets. On both coolers it was noted that both of these plates had split where there is a detent to hold the plate in position. This also happen to be where the plate is at its most narrow point. Is …
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in: Cummins Marine Engines
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Helm pump for 85 Foot trawler
This topic has 3 replies, has 2 voices, and was last updated by
1 month ago November 15, 2025 at 12:02 pm Hi I have a 85 feet trawler using it as yacht … I am about to install the steering system, Two engines , 800 Horse Power , V hull, Pocket tunnel .. what type of helm pumps do I need to install,, My understanding that i need a 90 Bar , Helm pump , is that true …thank you ..
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in: General Discussion
3 RepliesNovember 15, 2025 at 7:34 pm 1——sent or post pictures of all the components and parts of the current steering system that you are re-engineering from ?? to hydraulic steering. Everything means EVERYTHING from the helm station(s) and steering wheels, and all cables, fittings, connections, etc. from there to the equipment in the aft lazzerete where the rudder shaft(s) are, and the rudders themselves under the vessel. No one here could have a clue as to what you h…Last Post by:
posted: 1 month ago
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Post break in
This topic has 1 reply, has 2 voices, and was last updated by
1 month ago November 14, 2025 at 9:47 am Just rebuild my 4bta 250hp, i have ran the engine 4 hr with tony procedure varying rpm and holding cruise for 25% and short burst WOT. All seems well and in spec. Question is post break in should the oil be changed now, 20hrs or 50hrs? Also anything else that needs to be rechecked, retorqued etc? Tom
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in: Cummins Marine Engines
1 ReplyNovember 15, 2025 at 8:44 am IMO– anything from 25-50 hrs is fine————Cut open the filter for a peek on the outside pleats.. I’m sure all is good, but seeing what is not there can make to sleep better at night. Seaboard Founder & PresidentLast Post by:
posted: 1 month ago
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ZF 286 clunk when shifting
This topic has 3 replies, has 3 voices, and was last updated by
1 month ago
November 9, 2025 at 8:59 am I have a ZF 286 mated to a QSC 8.3. I recently had the PSS Shaft seal replaced which required the shaft to be pulled and the prop removed. The new shaft seal is working properly with no evidence of leaks. I am now getting a “clunk” when shifting from forward to reverse and vice versa. Mechanic has checked the shaft coupler and says it is fine. My next step is to haul the boat and check the prop to ensure it is secure. Transmissio…
Started by:
in: Marine Transmissions
3 RepliesNovember 13, 2025 at 12:31 pm Diver found the prop nuts were not tightened properly. Said he put 2 1/2 more turns on them. Problem seems to be resolved.Last Post by:
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6BTA starts without me asking it to.
This topic has 7 replies, has 2 voices, and was last updated by
1 month ago
November 9, 2025 at 3:10 am Hi all, New to me engines, and am figuring out what might be causing the stbd motor starter to engage when I’m not pressing the start button. My initial thought was a short in the wiring somewhere, because it seems the starter gets energised a little bit, then stops, then again etc… until engine starts by itself. when this happens the starter keeps trying to engage again after the engine has started… and it’s a bit tricky to get it to st…
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in: Cummins Marine Engines
7 RepliesNovember 13, 2025 at 7:08 am Thanks for the help. Turns out someone replaced the mag switch with a bosch 30amp relay… and that coupled with bypassing the 10amp reset fuse and some corroded connectors… and well… let’s just say I’m lucky there wasn’t a fire. Thanks to the awesome resource here I’ll be making a new harness and getting rid of all the bullshit wiring. Cheers 🙂Last Post by:
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6CTA Exhaust elbow cooling jacket?
This topic has 9 replies, has 5 voices, and was last updated by
1 month ago November 9, 2025 at 1:06 pm Hello, I have a 99 Tiara 4000 with twin Cummins 6CTAs that we recently took ownership of. During our 350mi return trip it became evident that we had a serious exhaust gas leak issue on the port engine. When we removed the bolts from the turbo outlet the exhaust elbow fell off and it was clear that the stainless steel pipe has sheared off right at the showerhead junction under the insulation. We were able to weld the exhaust elbow and wrap…
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in: Cummins Marine Engines
9 RepliesNovember 12, 2025 at 4:59 pm Riser one————-Rob is lucky–Caught it early with a minimum of turbo damage We’ll see number two soon For those that “think is is acceptable” as it it lasted 20 yrs?? —Just based on the OUTSIDE WALL seepage, what do you think is going on the with inner way or tube? ————–To me that is beyond sad———————-This is only 1200…Last Post by:
posted: 1 month ago
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6BTA Heat Exchanger Service
This topic has 9 replies, has 6 voices, and was last updated by
1 month ago April 27, 2020 at 9:28 am Ready to service my HX’s and wondering if there are any tips or protocol similar to the Aftercooler protocol. All I can really find is people doing a recirculating flush with Rydlyme or similar but I’ve not seen anything about removing the core and doing a bench type service. Also wondering if a healthy application of Alco Metalube to the end parts is recommended as in the Aftercooler protocol. Thanks for any tips/pictures. Todd
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in: Cummins Marine Engines
9 RepliesNovember 12, 2025 at 6:59 am That works. If you are experiencing a slight pressure loss be prepared to dunk the unit or spray soapy water on your caps, to check for leaks on your test setup, etc. Post some pics along the way. Rob "Luck is the residue of good design."Last Post by:
posted: 1 month ago
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Heat Exchanger Zinc Length Issue
This topic has 3 replies, has 3 voices, and was last updated by
1 month ago October 19, 2016 at 9:43 pm The later style Champ heat exchanger (offset inlet/outlet) appears to have a zinc length issue which is confirmed by some and negated by others. Strange that the feedback differs but I can only speak to my findings. My heat exchanger zinc DOES bottom out against the end casting. I did not realize it on my first zinc change. I do not go tight-tight on the zincs so no damage was done and it clearly had enough threads engaged to make a watertig…
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in: Cummins Marine Engines
3 RepliesNovember 12, 2025 at 6:53 am RS5 is available in the brush can as well but use your flavor of choice, not mission critical for the zinc caps. Rob "Luck is the residue of good design."Last Post by:
posted: 1 month ago
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Fuel shutoff solenoid
This topic has 1 reply, has 1 voices, and was last updated by
1 month ago November 10, 2025 at 4:08 pm Hey all, I have a cummins 4bta 250 hp that we just rebuilt. The fuel shut off solenoid is pulling in when we start the engine but when the key is let go into run the solenoid kicks off. I was suspecting the solenoid its self so i swapped from the port engine which is know good and working and same dice on the starboard. From my understanding this is just getting 12v from the on position but voltage at the plug is the same as port. What co…
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in: Cummins Marine Engines
1 ReplyNovember 12, 2025 at 5:15 am Figured it out after talking to larry b who makes shutoff solenoids. Ended up being the adjustment length. The lever was bottoming out before the solenoid was bottoming out so it couldnt catch and hold. TomLast Post by:
posted: 1 month ago
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Shelf Life of Impellers
This topic has 1 reply, has 2 voices, and was last updated by
1 month ago
November 8, 2025 at 5:02 am Hi guys – first, thanks for all you do for our community (answers, articles, videos) – they are amazing and appreciated by the masses! I have a QSC in my boat and want to keep a spare impeller (Sherwood raw water pump, Sherwood 26000 or Seaboard Super 26 impeller). I have a couple Sherwood 26000 already on the boat, dated 2023. How long can these impellers sit on the shelf and still be ok to use? Should I lube them in some sort of gr…
Started by:
in: General Discussion
1 ReplyNovember 10, 2025 at 5:33 am Left out in the sun w/UV on them, not long. In a cool dark place, I would expect them to be fine for 10+ years. I would not lubricate an unflexed impeller sitting in a plastic bag.Last Post by:
posted: 1 month ago
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Water/fuel alarm triggered with no sensor hooked up
This topic has 2 replies, has 3 voices, and was last updated by
1 month ago November 8, 2025 at 9:01 pm Bought my boat used there’s currently no sensor on the racar or fuel filter it went into alarm my last trip out stopped the boat promptly and replace the racar. Still the issue continues any help will be appreciated
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in: Cummins Marine Engines
2 RepliesNovember 9, 2025 at 5:44 pm Would be helpful if you included your engine model. How to handle Water in Fuel (WIF) Circuit / Sensor False Alarms Rob "Luck is the residue of good design."Last Post by:
posted: 1 month ago
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160 degree thermostat
This topic has 3 replies, has 3 voices, and was last updated by
1 month 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
3 RepliesNovember 9, 2025 at 4:22 pm Not opposing opinions, but no definitive answer, guess I’ll stay with 160’s. Thanks for the information.Last Post by:
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Remove fuel cooler – QSM-11
