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QSC approaching 5000 hours, major maintenance?
This topic has 2 replies, has 2 voices, and was last updated by
1 month ago
March 17, 2024 at 2:20 am Hello experts, Our QSC8.3 490hp 2006 vintage just passed 4000 hours and I hear some people saying that 5000 hours is some “milestone” when major maintenance should be in order? I know Cummins is prescribing a valve adjustment at 5000 hours (which seems a huge amount to me for this but who am I to judge). Some info on our installation: single engined full displacement trawler; semi live aboards, engine runs regularly most of the year…
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in: Cummins Marine Engines
2 RepliesMarch 17, 2024 at 9:17 am Thanks for the tips Tony. Most is still original except for the seawater pump and engine mounts (both replaced this year). As said we run >95% of time around 1300 rpm which in our case is 3 – 4 GPH. I keep an eye on the belt (approx. 3 yo). Seems fine but creates quite a bit of dust. We have conventional shaft drive through TwinDisc MG5091SC transmission. No ZEUS. Cheers, AndrĆ©Last Post by:
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QSC runs a bit rough at certain revs
This topic has 6 replies, has 2 voices, and was last updated by
April 12, 2023 at 3:59 am Goodmorning Sailors, This is a question in the category: is this normal? As long as we have our single QSC490 trawler I have always noticed certain revpoints where there is much more shaking of the engine than others. In our case this is between 800 and 900 and between 1550 and 1850. Especially the latter window is quite noticeable. Up to 1500 revs the engine runs very smooth but beyond that you feel a roughness going through the boat which smoo…
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6 RepliesMay 5, 2023 at 11:38 pm Thanks Tony. It certainly looks like it. It seems like some …hole has tried to realign that mount by turning the jamnut against the rubber. Now I have returned the jam nut in it’s proper position the snubber has already recovered a tiny bit. When I shine a light behind it I can see it’s not touching the SS bases anymore…although on ly by a fraction of a mm. What is the normal life span of these engine mounts (these are 15…Last Post by:
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Losing coolant at rest
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This topic has 28 replies, has 8 voices, and was last updated by
1 year ago
January 8, 2023 at 4:49 am Goodmorning sailors, I have a nagging problem that I hope somebody can shed some light on. On our QSC8.3 490hp of 2006 vintage I have to add about a quart of coolant every 100 running hours or so. I already have taken of the turbo and replaced the exhaust seal as I thought it might be disappearing through the exhaust. This did not solve the problem. Oil is staying clean and at level, no funny smoke at startup, no coolant under engine, no coolant…
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April 12, 2023 at 4:40 am Thank you for the update and glad to hear all worked out.
28 Replies
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posted: 1 year ago
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Bubbles in Racors continued
This topic has 5 replies, has 2 voices, and was last updated by
2 years ago July 6, 2021 at 12:24 am Goodmorning members, Due to some unknown digital glitch I could not access my original post on this topic again. Hence this new one about the same challenge. In the meantime did some more tests and took some stuff apart…to no avail. Please read my original post for a detailed description and some video footage of the bubbels in the Racor as well as some pictures of the lay out. In addition I can tell: – The system from tank to engine…
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5 RepliesJuly 6, 2021 at 9:38 am Andre, I have much experience with weird problems. LOL You could run a small container of diesel directly to the RACOR input. That could isolate the problem to the racor or before the racor. This type of conversation is ALWAYS good for the community to learn from, especially troubleshooting methods and ideas IDK the reason for a check valve in a racor (redundancy in the system maybe). I use fleetguard filters and housing (no check valve that…Last Post by:
posted: 2 years ago
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Clicking noises from Mastercraft alarm
This topic has 12 replies, has 3 voices, and was last updated by
July 24, 2020 at 12:27 am Goodmorning forum, This morning leaving the harbor I thought I just heared a rattle of something. After a few minutes it started to annoy me so went looking. It actually came from the black alarm speaker in the Cummins QSC8.3 dash on the flybridge. Downstairs in the Pilothouse the same thing. It sounds quite ritmic, mostly resembling some Spanish castagnette . This was all in warm up phase around 900 revs. Everything looked normal, temp, oil pre…
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12 RepliesJuly 5, 2021 at 11:52 pm Found it! Goodmorning members from sunny Corfu. I was going through my older posts and thought it might benefit everybody to post final solutions to some nagging problems. This specific one turned out to be a flacky exhaust temp sensor which is mounted on the mixer. At certain revs this (quite huge) exhaust riser/mixer is shacking a bit which caused the sensor to trip momentarily and repeatedly. This created the annoying ticking sounds from the …Last Post by:
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Bubbles in Racors
This topic has 14 replies, has 3 voices, and was last updated by
2 years ago
June 13, 2021 at 12:31 am Goodmorning sailors, I would like to pick your brains on a problem that has been driving me crazy lately. I know it’s not specifically Cummins but I think close enough. We have a Selene 53 with single QSC8.3 490 Hp 2007. We are semi live aboards so the boat gets frequent work outs. Already for a longer period I notice air bubbels escaping the turbine wheel in our Racor 1000MAX set. About 2 tiny bubbels every 5 seconds. the entire circuit f…
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14 RepliesJune 15, 2021 at 7:45 am For some reason your latest post is showing up on the main forum page but is not appearing in the thread. I can understand why this is baffling to you. The fact that the bubble formation didn’t increase significantly when closing the valves does seem to indicate the air is being introduced somewhere between the valves and the surface of the fuel in the tanks. And, to your point, it happens with either tank so it would seem there are at l…Last Post by:
posted: 2 years ago
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Seawaterside empty or filled with fresh water?
This topic has 1 reply, has 2 voices, and was last updated by
4 years ago November 25, 2019 at 1:37 am Goodmorning, Our single QSC 490 is normally fresh water flushed when planned to be stationary for more than 2 weeks. A valve connector on the strainer makes this easy. Over the last couple of days I did some maintenance jobs for which I did empty the seawater side of the cooling system. The boat will not be used for the next 3 months. It’s in salt water in Southern Greece at the moment, no frost. I’m wondering what’s better: le…
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1 ReplyNovember 25, 2019 at 6:44 am IMO—————————–Keep fresh water in it even if unused used for a year or more… TonyLast Post by:
posted: 4 years ago
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Anodes in oil coolers
This topic has 4 replies, has 4 voices, and was last updated by
June 23, 2019 at 12:05 am Goodmorning, On the back of our QSC8.3 are 2 oilcoolers (see aolso attached pictures) – Mota transmission oil cooler for the Twindisc – Mota hydraulic oil cooler of which Wesmar stabilizers, bow and stern thruster run. The transmission cooler does not have any anode in it which has always surprised me. It is also a more complex devices of which I guess it has some thermostatic function? The (upper) hydraulic oil cooler is a very simp…
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4 RepliesJune 23, 2019 at 10:52 pm Thanks for all the advice. If anything I found a topic that even Tony is unsure about š To ponder a little more. We have a Northern Lights genny with a Lugger diesel. In this Lugger there ZERO anodes which always baffled me. However one of the things they did that might explain this, is isolate the core in the HX. This is only clamped in rubber no contact with any other metal. That’s what started me thinking on the isolation of the hydraul…Last Post by:
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bubbles in Racor
This topic has 2 replies, has 3 voices, and was last updated by
5 years ago
April 27, 2019 at 12:57 am Hello, Our QSC8.3 500 is running fine. During a routine check underway (running at 1500 revs) I noticed a few (air)bubbles coming from the white centrifuge part in the bowl of the Racor filter. Not continouos but every 20 sec or so a bubble escapes. Filter is clean, vacuum gauge is low, tanks are full (meaning above the level of the Racor). There are no visible leaks. I know diesel can form vapor bubbles in pressure differences. what do you thin…
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2 RepliesApril 28, 2019 at 6:58 pm I had a very similar problem 3 years ago. I saw bubbles in the port Racor but the engine was running perfect. One day we went out and ran about an hour away from home port. We anchored up and after a few hours got underway again. Port engine rpm was going up and down some at idle in gear. I ran her up on plane with no problems. We headed back to the marina and when I slowed down to idle the port engine was hunting badly in gear (rpm up and down)…Last Post by:
posted: 5 years ago
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QSC 8.3 HX outlet tube removal
This topic has 7 replies, has 3 voices, and was last updated by
February 25, 2019 at 5:49 am Goodmorning, I got a small but very annoying problem. I don’t seem able to remove the lower end of the bend metal tube that goes from the Heat exchanger to the Thermostat. The original bolts seem to be 10mm (instead of the 3/8″ I expected). I got the 2 that hold the upper part in the HX out (needed quite some force, maybe loctite?). However the rear bolt at the lower end is very hard to get to (without removing the entire exhaust man…
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7 RepliesFebruary 27, 2019 at 10:47 pm Exactly Rob, that’s it! You managed to make a much better picture than I š The problem is the exhaust is very close to the bolt, so the swivel mechanism that I have is to big to fit in the socket. Probably there are swivels that are more geared to this situationā¦ I frankly abandoned the job for now as I’m afraid of breaking stuff. Not sure why these bolts (all 4) need so much force to come loose. They are clean and not corroded when …Last Post by:
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Fuel filter change interval
This topic has 6 replies, has 3 voices, and was last updated by
5 years ago November 12, 2018 at 1:19 am Goodmorning forum, I know fuel filtration is a much debated topic with good articles on this site. However I just found out my on-engine filter on QSC8.3 500hp has been there for 1200 hours now! It’s a single engine installation in a Selene 53 trawler that is run all year round with some intervals. Typically averaging 500 hours/year. Setup: – 5000 liter tank capacity (cross ocean range) in GRP tanks; – ESI fuel polishing system…
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6 RepliesNovember 13, 2018 at 8:37 am See I knew Rob would have the answer. Share some pics when you cut it open.Last Post by:
posted: 5 years ago
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Coolant loss QSC8.3
This topic has 6 replies, has 2 voices, and was last updated by
May 19, 2018 at 11:16 pm Our single QSC8.3 500hp from 2006 is loosing around 1 quart of coolant every 15 engine hours. Before the winter we have changed the coolant and also did a replacement of the exhaust manifold to turbo gasket as it was dripping a little bit of coolant to the outside. All seemed well and clean during replacement. We started cruising end of March and since then we did 50 engine hours. At first I thought the engine was just burping air from the coola…
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6 RepliesMay 29, 2018 at 12:01 pm Just to close this topic. I got the replacement gasket en the silicone gasket stuff…and the day before I planned to do the repair the engine suddenly started building up coolant in the expansion tank during a heat cycle and stopped loosing coolant. Since then been through 6 heat cycles and no problem or loss of coolant anymore. I have no clue why? Might be it took an extremely long time (50 engine hours!) to burp the engine after the coola…Last Post by:
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QSC approaching 5000 hours, major maintenance?
