Cummins Marine Diesel Repower Specialists › Forums › Cummins Marine Engines › 175 RPMS OFF MY MAX OF 2800? HELP!

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  • December 15, 2016 at 9:21 am #13647

    Austin.Ensor
    Participant

    Hello all I am looking for some guidance here,

    I have year 2000 Cummins 6BTA’s in my 28 Carolina classic with 1400 hours on them. 1000 service done.  At the end of this Season I was showing my port engine off the max by approx. 175 RPMS. At max throttle my Port was 2625 and my Starboard was 2760. Max for the motors is 2800. I thought I had a prop issue. Finding out from wild cat both the props were the same this tells me I have a port Engine Issue that is causing it to not make as much horse power as it should. We did a No load test on the boat this summer and both motors maxed out around 3200 (It could have been 3300 I don’t Fully remember) and Ed said that was fine. Just want to see what you think it could be assume RPMS are correct and props are the same?

    Overall, while under load my port engine is not making as much power as the starboard.

    What should I investigate first? Thank you-Austin Ensor

     

     

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Viewing 15 replies - 1 through 15 (of 15 total)
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  • December 21, 2016 at 9:34 am #13882

    Austin.Ensor
    Participant

    WILL DO

    I WILL BE TO THE BOAT ON JAN 1ST I WILL GET THESE PICS FOR YOU.

    -AUSTIN

    December 17, 2016 at 8:54 am #13726

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    No not 2900—  OVER an ACCURATE 2900 RPM and that needs to come VERY easy when you are loaded to the max….  See the words  “OVER” & “VERY easy”

     

    Can you take a high res picture of the tops of both aftercoolers–Clear & in-focus and sends them to me direct. Prefer both side & straight down top views

     

    TonyAftercooler Cap

    December 17, 2016 at 8:35 am #13725

    Austin.Ensor
    Participant

    TONY

    #1 Correct not 100% on the past speeds.

    So I need to be able to achieve 2900 on those motors. If Im reaching 2800 that means Im Over propped?

     

    The pic was after the 1000 hr service correct.

     

     

    1 user thanked author for this post.
    victor brunst
    December 16, 2016 at 6:16 pm #13720

    Rob Schepis
    Forum Moderator
    Vessel Name: Tenacious
    Engines: 6BTA 5.9 330's - "Seaboard Style"
    Location: Long Island, NY
    Country: USA

    Tight !

    Wow, I hope you have a skinny mechanic!

    I see no risers.  Have you identified the loaded waterline?  Do you have better photos coming of the turbos and exhaust?

    December 16, 2016 at 5:33 pm #13707

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

     

    “FIRST”———So, does that mean  you really have no real clue about past speeds at the sames RPM’s, like at 2400?  You are just guessing?  That;s OK, but I have to know to help.

    After #7—————–The past owner was 100% wrong.. As to your mechanic, his opinion is irrelevant on this unless he is on the boat when you use it as it is used when you do what your do… It’s  over an ACCURATE 2900 RPM and that needs to come VERY easy when you are loaded to the max….

    As to the rest–do what needs to be done..

     

    Your pictures of the engines—————Were these taken before of after the 1000 Hours service?

     

    Tony

     

    December 16, 2016 at 7:51 am #13690

    Austin.Ensor
    Participant

    responce

    First–you are 100% sure your vessel travels at the same speed  at 2400RPM  as it did last year. Not any slower?  This is important.
    I am not 100% sure of this because I did not own it then I can get in touch with the previous owner.

     

    NEXT:

    Are you positive the aftercoolers were removed  from the engines a completely dissembled / Cores removed?  Did you actually see that?  The vintage of your aftercoolers suggests you have “Aluminum cored units” and at 16 yrs of Marine Age on them, unless they were regularly serviced  this way, they’d never come apart– The term “clean & flush” does not sit well with me.
    I trust that my mechanic did the most he could to clean the aftercoolers but I will   specifically ask.

    2) During your slow climb getting on plane–any dark smoke at all from the exhaust?

    Have not seen any dark smoke since ownership of the vessel.

    3) Thottle Cable–You verified that the throttle arm on the injection pump is 100% up against the stop?

    I did but I will confirm again.

    4) Fuel solenoid lever–You verified that the fuel solenoid that pulls up the fuel lever is holding hard 100% up against the stop?

    I did but I will confirm again.

     

    5) Has you engine tach accuracy ever been verified at say 2600 RPM at the dock in neutral?

    They have not.

     

    6) You need to get a boost gauge—————-0-30 PSI  and get some readings

    I will get a boost gauge readings at various rpms.

     

     

    7) I want to see your engines as installed in the boat–All angles & perspectives, and especially the exhaust & turbo.. All clear & in focus.. After seeing your gear, I need to seem the rest.

    See pics these are all the pics I have of engine compartment.

    You do realize they your engines when new an fresh, they were rated at 315 BHP at 2800 RPM MINIMUM  (NOT 330 HP) ,  and  that for propping purposes, they should have seen , from Day 1, over 2900 and seen it easily, right?

    The owner recommended the boat top RPM at 2800 rpm. I will ask the mechanic about this also.

    December 16, 2016 at 7:39 am #13686

    Austin.Ensor
    Participant

    MORE

    MORE

    December 16, 2016 at 7:38 am #13680

    Austin.Ensor
    Participant

    MORE PICS

    MORE PICS

    December 16, 2016 at 7:36 am #13675

    Austin.Ensor
    Participant

    PICS

    PICS

    December 16, 2016 at 6:40 am #13674

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Let’s clarify somethings—

    You have read this and followed each step in sequence?

    Understanding Low Power Troubleshooting

    First–you are 100% sure your vessel travels at the same speed  at 2400RPM  as it did last year. Not any slower?  This is important.

     

    NEXT:

    1) Are you positive the aftercoolers were removed  from the engines a completely dissembled / Cores removed?  Did you actually see that?  The vintage of your aftercoolers suggests you have “Aluminum cored units” and at 16 yrs of Marine Age on them, unless they were regularly serviced  this way, they’d never come apart– The term “clean & flush” does not sit well with me.

    2) During your slow climb getting on plane–any dark smoke at all from the exhaust?

     

    3) Thottle Cable–You verified that the throttle arm on the injection pump is 100% up against the stop?

     

    4) Fuel solenoid lever–You verified that the fuel solenoid that pulls up the fuel lever is holding hard 100% up against the stop?

     

    5) Has you engine tach accuracy ever been verified at say 2600 RPM at the dock in neutral?

     

    6) You need to get a boost gauge—————-0-30 PSI  and get some readings

     

    7) I want to see your engines as installed in the boat–All angles & perspectives, and especially the exhaust & turbo.. All clear & in focus.. After seeing your gear, I need to seem the rest.

     

    You do realize they your engines when new an fresh, they were rated at 315 BHP at 2800 RPM MINIMUM  (NOT 330 HP) ,  and  that for propping purposes, they should have seen , from Day 1, over 2900 and seen it easily, right?

     

    Tony

    December 16, 2016 at 6:06 am #13673

    Austin.Ensor
    Participant

    Never mind it would not attach. Tony, if you want a copy of my out of water value survey I can email that to you. It has a lot of pictures that might help diagnose the issue.

    December 16, 2016 at 5:41 am #13670

    Austin.Ensor
    Participant

    Value Survey

    See value survey attached has a bunch of pictures that might help.

    December 16, 2016 at 5:40 am #13669

    Austin.Ensor
    Participant

    Info.

    Thank you for the timely response. I recently purchased your hose kit for my engines and couldn’t be happier with what I got. Below I have answered your questions to the best of my knowledge.

    1)      Go back month or ?? when all was right (Post an approx. date) — Tell me what you vessel speed was at 2200 RPM, 2300 RPM, &  2400 RPM..

    Everything was ok approx. 07/15/16 I do not know speeds at 2200 and 2300 but I normally cruised the boat at 2400 and saw speeds 24-26 kts depending out outside factors.

    2)      Tell me what you vessel speeds is now at these same RPM’s

    Speeds are the same are the same now but I have to add more throttle to the port in order to get the 2400 rpms out of the motor. This is how I get on plane… I idle the boat for approx a mile, I slowly inch throttles forward untill I reach 1800 Rpms. (I have to push port harder to get there) once there I start moving throttles up untill both motors are at 2400. The port engine throttle is pushed farther than the starboard. I checked the cable and both max out at the same location so its not a throttle cable issue.

    3)      Tell me if there has been any changes in the prop between #1 & #2.

    According to wild cat propellers who do the measurements by laser the props are the same.  They were the first ones to let me know I had an engine problem when I assumed I had a prop issue.

    4)      Tell me EXACTLY what was done in your 1000 hrs service?

    New engine belts, new zincs, gear oil change and flush cooler, inspect turbo charger and check clearance,  inspect tensioner,  valve adjustment, inspect engine mounts, inspect air filters.

    -Clean and Flush aftercoolers

    -Heat exchanger and cooling system flush

    -replaced idler pulley #4991240 and tensioner #5333477

    -washer seal replaced part # 3910556

    -water pumps replaced #4089731

    -coolant change CC2825

    -Said some valves were tight some were loose.

    Note the 1000 hour service did not correct my issue I was having before and after the service.

     

    Tell me how long the vessel has operated in SALT water —   I want YEARS & MONTHS.

    The vessel has operated in salt water since built in year 2000 so 16 years 6 months total time there although the boat has been shed kept from Dec1- April 1 every year. Boat operates in Ocean city Maryland so 118 months in salt water use. Used for offshore fishing there.

    –Tell me when (DATE and engine  hours ago) the aftercooler was REMOVED from the engine and serviced per my protocol on the bench?

    11/25/16 1000 hour service done.  Note I was having issue before and after 1000 service.

     

    7) Tell me how many owners since new and your engine serial number..

    Two owners total.  One owner who had the boat built from 2000-2015 and myself 2015- current.

    Port: 45930019   starboard: 45928140

    December 15, 2016 at 8:22 pm #13668

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Answer these questions exactly as asked :

     

    1) Go back month or ?? when all was right (Post an approx date) — Tell me what you vessel speed was at 2200 RPM, 2300 RPM, &  2400 RPM..

    2) Tell me what you vessel speeds is now at these same RPM’s

    3) Tell me if there has been any changes in the prop between #1 & #2..

    4) Tell me EXACTLY what was done in your 1000 hrs service?

    ) Tell me how long the vessel has operated in SALT water  —   I want YEARS & MONTHS.

    6) Tell me when (DATE and engine  hours ago) the aftercooler was REMOVED from the engine and serviced per my protocol on the bench?

    7) Tell me how many owners since new and your engine serial number..

     

    SEVEN simple questions require SEVEN simple answers for me to move fwd & sort yo otut

     

    Tony

     

     

    December 15, 2016 at 7:08 pm #13667

    Woo
    Participant
    Vessel Name: Obsession
    Engines: 6BTA5.9M3 (370) x 2
    Location: East Coast
    Country: Australia

    I’m in Australia and have only seen one in person, but via the interwebs I note that the CC boats seem to be very nice hulls, with generally appalling exhaust layouts and design. Some of the worst in fact.

     

    Can you show us some pictures of your engine space? If it’s like most, the turbos will be getting a good salt water bath.

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