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Volvo D6-435I-E WOT issue

Discussion in 'Engines' started by Seasmaster, May 31, 2018.

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  1. Seasmaster, May 31, 2018
    #1
    Seasmaster

    Seasmaster Senior Member

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    Hoping one of the VOLVO guru's can help out.

    Have a 2012 engine with 868 hours that won't go to wide-open-throttle (WOT) RPM's smoothly after a good 10 minute warm up at 1500-1800 RPM's. When the throttle advanced, is the engine will rev up to 3100 RPM's immediately, pause for a few seconds, then creep up to 3320 RPM's. This is repeated every time.

    The engine guy replaced the turbo sensor that was giving a false boost reading of 45psi, when max is 30. After installing the new sensor, the turbo pressure reads correctly, but the WOT problem persists.

    The turbo spins freely (mechanic did a manual/physical inspection-no fouling), verified fuel delivery is good (filters are clean), verified air filter not blocked. When he had computer hooked up, all readings appeared normal. At WOT, the computer indicates the engine is working at 100%. Compression check was average of 95% for the 6 cylinders.

    Any ideas?
  2. Seasmaster, Jun 5, 2018
    #2
    Seasmaster

    Seasmaster Senior Member

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    Holy cow!!! No Volvo experts weighing in on this? Yikes!!! I must have the "unicorn" problem. . . LOL
  3. Capt Ralph, Jun 5, 2018
    #3
    Capt Ralph

    Capt Ralph Senior Member

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    What color is the exhaust?
    Assuming single engine setup.
    Any fuel vacuum gauges or after pump pressure gauge?

    I'm low tech but back to basics works
    on all engines.
  4. f3504x4ps, Jun 5, 2018
    #4
    f3504x4ps

    f3504x4ps Member

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    This engine has turbo and supercharger correct? Turbo is for take off to mid till supercharger fully kicks in. Have you verified that the clutch for the supercharger engages/energizes?
  5. Capt Ralph, Jun 5, 2018
    #5
    Capt Ralph

    Capt Ralph Senior Member

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    Ah, one of those?
    Blower for take off, then turbo. It's not a by-pass blower and has to free wheel to let the turbo apply pressure.
    I remember reading something years ago of a delay when the blower disengages and holds it down.
    Some boating rag and thought to be normal.
  6. f3504x4ps, Jun 5, 2018
    #6
    f3504x4ps

    f3504x4ps Member

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    Your right I was reversed blower to reduce turbo lag. Thanks Capt Ralph. Hope your feeling better
  7. Capt Ralph, Jun 5, 2018
    #7
    Capt Ralph

    Capt Ralph Senior Member

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    Lott's better.
    Thank you
  8. Ken Bracewell, Jun 5, 2018
    #8
    Ken Bracewell

    Ken Bracewell Senior Member

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    I recall having a similar problem with a tender once. It was the waste-gate solenoid. Had to replace the whole unit. Try manually opening the valve when you're running at turbo RPM.
  9. Seasmaster, Jun 5, 2018
    #9
    Seasmaster

    Seasmaster Senior Member

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    Hi Cap'n R and thanks for the reply.

    Single engine setup/Exhaust color neutral (clear), not black, not white.
    No gauges. When engine guy had his computer hooked up, he indicated that fuel delivery wasn't a problem.
    He appeared to be pretty though with his trouble shooting - and he mentioned that his conversation with other volvo tech's that the turbo pressure switch was the original problem, hence the change. The old one did have a compromised bulb on the sensor tip.
  10. Seasmaster, Jun 5, 2018
    #10
    Seasmaster

    Seasmaster Senior Member

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    I'd say "yes". When the volvo tech was aboard, he told me to "slam" the throttle from "engaged idle" to WOT. There was a definite and short "turbo bark" when it engaged.
  11. Capt J, Jun 5, 2018
    #11
    Capt J

    Capt J Senior Member

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    How clean is the bottom? It sounds more like a dirty bottom/running gear.
  12. Capt Ralph, Jun 5, 2018
    #12
    Capt Ralph

    Capt Ralph Senior Member

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    Play with the waist gate.
    Go fishing. Your not running that fast normally anyway.
  13. Seasmaster, Jun 5, 2018
    #13
    Seasmaster

    Seasmaster Senior Member

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    Ken,
    Thanks for the tip. I'll pass on to engine guy
    Nope: Boat hauled in May. Clean bottom/clean wheel
  14. Seasmaster, Jun 5, 2018
    #14
    Seasmaster

    Seasmaster Senior Member

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    Roger fishing. But it's the idea the engine wasn't "stalling" on the acceleration before, and now it is.
    But I'll look into the waste gate! Thanks.
  15. Capt Ralph, Jun 5, 2018
    #15
    Capt Ralph

    Capt Ralph Senior Member

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    BEFORE?? I must have missed read something. BEFORE what exactly.
    I thought the boost sender was replaced in trying to correct this problem.
  16. Seasmaster, Jun 6, 2018
    #16
    Seasmaster

    Seasmaster Senior Member

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    Sorry for confusion.

    When engine had "annual" done there was no "stalling". After about 4 months, the stalling (or pausing) problem suddenly developed. When first observed, the engine would pause at 3100 rpm's for about 8 to 10 minutes, before slowly advancing to 3320 rpm (almost like a "load" program on a SULZER slow-speed diesel on merchant ships), although the throttle position was full ahead.

    After the replacement of the turbo sensor, the engine still pauses at 3100 rpms, but almost immediately advances to 3320 very slowly, like the SULZER load program. The time interval between 3100 and WOT is now about 2 minutes, maybe 3.
  17. Capt Ralph, Jun 6, 2018
    #17
    Capt Ralph

    Capt Ralph Senior Member

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    I still like Ken's idea, wiggle the waste gate and try to change the symptom.
    Does this gate work on air pressure or electric servo?
    Check the waste gate linkage, lever bent, leaned or stepped on.
    Is the blower for sure dis-engaging?

    Was the inter-cooler serviced? Some flake/scale flying around covering a sender or passage?
  18. Capt Ralph, Jun 6, 2018
    #18
    Capt Ralph

    Capt Ralph Senior Member

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    I'd still like to know the fuel pressure and flow just before the injector pump.
  19. Capt J, Jun 6, 2018
    #19
    Capt J

    Capt J Senior Member

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    I agree with Capt Ralph. Verify fuel pressure. Also try removing the air filter and see if that fixes it. I once delivered a Volvo boat that progressively kept losing rpm's at cruise and started slowly black smoking. It was the air filters and they were Volvo's white pleated ones.
  20. Seasmaster, Jun 6, 2018
    #20
    Seasmaster

    Seasmaster Senior Member

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    When the mechanic was aboard, I seem to recall he disconnected the airbox-hence no air restriction. But the fuel pressure? Yeah, that sounds interesting.

    The Heat Exchanger, Intercooler, and oil cooler were all removed and cleaned in August 2017. Only 50 hours on engine since service (I'm embarrassed to say - I need to get out more. But since I'm now officially retired, I can!!LOL