Official Cummins QSC-500 Thread

Discussion in 'Diesel Engines/Drives/Transmissions/Props' started by Hampton, Nov 16, 2011.

  1. Tman

    Tman Member SILVER Sponsor

    272
    Aug 10, 2012
    Seattle, WA
    2014 Sabre 48 Salon Express
    Twin Cummins QSC 550
    Zeus Pod Drives
    I’m sure many real world procedures. What I would recommend is that you change your racor filter elements first...per the procedure outlined in those attachments you posted is fine. However, Run the engines a bit before changing the spin-on fuel filter on the engine. The reason is when changing the racor filter elements, it tends to dislodge ‘stuff’ and you want your older on-engine filter to catch that ‘stuff’. Then go ahead and change that on-engine spinon filter. Do not fill that filter with fuel though. Install it dry and then prime your system.

    Tom
     
  2. Robski97

    Robski97 Well-Known Member PLATINUM Sponsor

    Jan 15, 2007
    North Bellmore, NY
    44DA
    Cummins QSC 8.3's
    Why am I thinking bad injector ? Would explain running fine at idle …

    Rob
     
  3. Tman

    Tman Member SILVER Sponsor

    272
    Aug 10, 2012
    Seattle, WA
    2014 Sabre 48 Salon Express
    Twin Cummins QSC 550
    Zeus Pod Drives
    Bajturner - Do you happen to notice excessive crank times at start-up on that port engine? The engine should fire up in 3 to 5 seconds. Longer crank times could point to a bad injector.

    Rob - I too think it could very well be an injector issue. Somewhat easy to run through the balance of troubleshooting of the fuel and air systems and if all clear on those, it starts pointing more specifically at the potential of it being an injector.
     
  4. swaterhouse

    swaterhouse Member GOLD Sponsor

    307
    Jan 7, 2015
    Mattapoisett, MA
    2007 Sundancer 44
    Cummins QSC 8.3
    Lots of great troubleshooting tips so far, keep us posted on how further testing works out.

    Just one other bit of advice, diesels usually not all that happy sitting at idle with no load. Not sure how long you let them warm up at dock, but I was told start up, check initial oil pressures/verify water flowing out exhaust, then start tossing lines. We spend no more than 3 minutes at dock with engines running, usually its 2. Then idle until temps start to climb up to say 100, to fast idle to 130+ and then good to go with slow startup (assuming your out of no wake zone by then).

    Same thing on way back, slow decrease in speed to idle, secure lines (maybe not even all of them and shut down), idle time at dock is less than 1 minute unless I am alone, then it might be 2 minutes while I secure the bow and get back to shut down.
     
  5. bajturner

    bajturner Member GOLD Sponsor

    502
    Aug 17, 2010
    Ottawa, Ontario, Canada
    2008 44 Sedan Bridge, Avon 380DL RIB w/ Yamaha 40, Highfield CL290 RIB w/ Tohatsu 9.8
    Twin QSC-500 HO
    It started a little rough in the morning on Friday...fired immediately, but then stumbled up to rpm, with a fair bit of black smoke. Boat ran on-plane no problem, but the port engine was showing 100% load when the starboard was showing about 65%.

    When I started them to return to the marina Saturday evening, however, it started perfectly. No smoke or anything. No stumbling or hesitating. The boost pressure was near zero while idling out, in sync with the starboard engine. I was thinking everything was sorted out. As soon as I gave it some throttle, though, it started stumbling again and took a while to recover to a smooth idle after I took it out of gear. I shut it down about 2 minutes later.
     
  6. bajturner

    bajturner Member GOLD Sponsor

    502
    Aug 17, 2010
    Ottawa, Ontario, Canada
    2008 44 Sedan Bridge, Avon 380DL RIB w/ Yamaha 40, Highfield CL290 RIB w/ Tohatsu 9.8
    Twin QSC-500 HO
    It didn't warm-up for very long. There were people on the dock having dinner so I didn't want to disturb them...maybe 4 to 5 minutes. Left the dock on slow idle. Switched to normal/fast idle once I cleared the dock and continued for about 10 minutes. Temps were climbing up at that point. Everything was running smoothly at this point...
     
  7. bajturner

    bajturner Member GOLD Sponsor

    502
    Aug 17, 2010
    Ottawa, Ontario, Canada
    2008 44 Sedan Bridge, Avon 380DL RIB w/ Yamaha 40, Highfield CL290 RIB w/ Tohatsu 9.8
    Twin QSC-500 HO
    Bit of an update. Filters all replaced and diesel conditioner added to tanks. I am an hour away from my boat so my marina is in charge of solving this problem. While they are open to my suggestions, they also have their own protocol and favourite products. Here is the diesel conditioner they used:

    upload_2018-6-15_8-33-39.png

    Seems to meet most of the recommendations in Franks article. Anyone have any experience with it?

    Here are the filters that were taken out:
    upload_2018-6-15_8-35-7.png

    I am not sure which one is port and which is starboard, I have asked the tech. There was no sign of microbial growth, and so far as I know, no water in the separator.

    The one from the port has had about 620 gallons through it, and the starboard about 460 gallons. Is the reason for the difference is to do with the new boat owner learning how the generator feed / return valves work!

    How do these look? Is this bad, typical, nothing remarkable? I have no prior experience.
    Any idea why one filter looks relatively clean on one half?

    Lake test today. As of this morning, the starboard fires-up immediately while the port is still a little rough. Waiting for more details...
     

    Attached Files:

  8. bajturner

    bajturner Member GOLD Sponsor

    502
    Aug 17, 2010
    Ottawa, Ontario, Canada
    2008 44 Sedan Bridge, Avon 380DL RIB w/ Yamaha 40, Highfield CL290 RIB w/ Tohatsu 9.8
    Twin QSC-500 HO
    One more thing...is there a typical lifetime in gallons of fuel for these filters?
     
  9. fwebster

    fwebster Well-Known Member TECHNICAL Contributor PLATINUM Sponsor

    Oct 6, 2006
    Middle Tennessee ; Panama City Beach, FL
    1996 450DA
    3116 Caterpillars
    The filters looks clean, but the real answer was in the Racor bowl. Did you drain the bowl and catch the debris the filter had caught? What did it look like?

    There is no lifetime expectancy for diesel fuel filters. How long they last is almost totally dependent upon the quality of fuel you pump into the boat, how much tank sludge/water is in it and how much water you are condensing in your tanks between fill ups. If you manage your fuel system as I recomended and use 30 micron Racor elements and OEM secondary filters then you should be able to change the filters at your annual service and have have no problems during the year.


    Your engines are QSC's which are electronically controlled. The ECM controls injector timing so if your engine has a rough idle on start up, something is wrong. I am 3500 miles away from the boat so obviously we can't observe the rough idle or see any exhaust smoke, but the most likely cause of a QSC rough idle and an engine not running up to full rpm is a cylinder not completely burning all the fuel that is injected or an injector not functioning properly. Neither problem is going to be fixed until you get the engine diagnosed by a qualified Ccummins technician. The worry here is that if an injector has some carbon build up on the tip and it spraying droplets rather than atomizinf the fuel properly, you get unburned fuel in the cylinder. That fuel will "wash out" the cylinder by washing the lubricating oil off the cylinder walls and that leads to premature piston, piston ring and cylinder liner wear. If it were mine, I wouldn't run the boat until you had Cummins look at it.
     
  10. bajturner

    bajturner Member GOLD Sponsor

    502
    Aug 17, 2010
    Ottawa, Ontario, Canada
    2008 44 Sedan Bridge, Avon 380DL RIB w/ Yamaha 40, Highfield CL290 RIB w/ Tohatsu 9.8
    Twin QSC-500 HO
    Thank you Frank.

    I didn't change the filters myself, so I have to rely on what the tech (not a Cummins tech) is telling me. The reply I got was:

    "No water visible, black sticky sludge in housing. Lots in racor on Port side, some on stbd."

    I will pass along your concerns, and if the engine is not running right at this point stop operation and get a Cummins tech to diagnose.
     

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