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TAMD74 doesn't reach full RPM

Discussion in 'Engines' started by Geo Bouch, Jul 3, 2023.

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  1. Geo Bouch, Jul 3, 2023
    #1
    Geo Bouch

    Geo Bouch New Member

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    I have changed fuel filters, oil filters, no issues with exhaust leaking... so, any idea why my two TAMD74EDC engines don't go beyond 2000 RPM?
    Is it safe to keep driving the boat with this limited RPM condition? (i think it is referred to it as Safe Mode)!
  2. Pascal, Jul 3, 2023
    #2
    Pascal

    Pascal Senior Member

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    First of all are you sure the bottom especially the running gear is clean? It takes very little growth of the props to loose a couple of hundred RPMs

    what are these engines rated at? 2300?

    any black smoke accelerating ?

    what is the history of the boat? How long have you had it, is this a new problem? When is the last time you were able to turn rated RPm?

    some boats need plenty of trim tabs to get on plane, are they working ?

    you re ok running the boat at low speed, like 1200-1400 rpm but anything higher you will be overloading them
  3. mapism, Jul 4, 2023
    #3
    mapism

    mapism Senior Member

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    I'm not sure of what the limp (or safe, that's just a synonim) mode max RPM is for your engines, but pretty sure it's much lower than 2000 rpm.
    So, I don't think that has anything to see with your problem.
    But there are several options left, depending on the answers to Pascal questions above.
    To which I would only add another one: what rpm do the engines reach with no gear engaged?
  4. Capt Ralph, Jul 4, 2023
    #4
    Capt Ralph

    Capt Ralph Senior Member

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  5. mapism, Jul 4, 2023
    #5
    mapism

    mapism Senior Member

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    Wow, that's actually SEVEN years ago, no less.
    I will never complain again about how slow my yard is in completing the jobs I commission to them. :D
  6. Geo Bouch, Jul 5, 2023
    #6
    Geo Bouch

    Geo Bouch New Member

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    Thanks for all your comments. The Volvo Penta TAMD74 engines are rated to run up to 2500 RPM. i had this issue when i first bought this boat 7 years ago, the issue then got resolved when i changed fuel filters, and oil filters. the props and bottom get cleaned once a month. no black smoke. the TAMD 74 engines could be revved up to 2000RPM (test mode limit) while in neutral. the trim tabs are working fine.
  7. Capt Ralph, Jul 5, 2023
    #7
    Capt Ralph

    Capt Ralph Senior Member

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    Well, you serviced the fuel filters again?

    IMO; Fuel filter issues are on the top of the list when not making RPM.
    Even with low hours between replacing.
  8. Metatron, Jul 5, 2023
    #8
    Metatron

    Metatron New Member

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  9. Geo Bouch, Jul 5, 2023
    #9
    Geo Bouch

    Geo Bouch New Member

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    i did change the fuel filters last week! No improvement in RPM behavior on both engines! The idea of fuel hoses delaminating on the inside is an interesting root cause to consider. But since both engines are not reaching full RPM with the sync off, and the fuel system on my 2002 sealine T47 is a duplicated, independent system, for each engine. The odds are that for each independent fuel line system to de-laminate at the same exact time is very low!!!
  10. Capt Ralph, Jul 5, 2023
    #10
    Capt Ralph

    Capt Ralph Senior Member

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    And from different tanks, neither engine makes WOT?
    Since this is a repeat issue, corrected with fuel filters the first time, I would still look in this direction.
    Any vacuum and/or pressure gauges installed yet?
  11. boatpoor, Jul 5, 2023
    #11
    boatpoor

    boatpoor Active Member

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    Have you personally inspected the wheels? If the blades feel like 40 grit sandpaper that'll cost you several hundred rpms. Any possible air restrictions?