Volvo tamd41A won’t hit 3900 rpm

Discussion in 'Downeast Engine Room' started by m williams, Apr 13, 2018.

  1. Blitzen

    Blitzen Captain

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    28 BHM, Transmission is hs1a 2.62. Prop is 22x19 4 blade
     
  2. m williams

    m williams Senior Member

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    According to 3 different prop guys I had way to small of a prop on the boat They where saying I should get 3900 with this prop. I thinking it mite be in the fuel pump. Engine starts run smoth. At 2900 rpm I am doing 15.5 knts. Before I was doing 9 knts at 2900
     
  3. m williams

    m williams Senior Member

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    The boat originally had a ms4 transmission 2.63 ratio 22x21 propeller
     
  4. Diesel Jerry

    Diesel Jerry Captain

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    Doesn't sound like a clear timeline. Did you change the fuel pump? Did this problem always exist? When did you loose the rpms, over time of suddenly?
     
  5. BillD

    BillD Captain

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    m-williams,

    Another question or two.
    "the rpm numbers you are providing the forum" ??
    Are ALL the rpm numbers you are providing here taken with a photo tach?? or just the most recent WOT rpm of 2975?

    OK, let's review.
    1. no load WOT at the dock rpm is 4,000 (throttle linkage fine, fuel pump is fully advanced).
    2. 3700 reached with a smaller prop in the past. (assuming everything was OK with the engine at that time the engine was over propped by 3" pitch)
    3. Here's where the trail is "fuzzy"...there was engine work done in 2016,,,turbo and injection pump"
    4. Did he go to a bigger prop at the same time as the engine work ? Yes? No ?
    5. Has a 2.62:1 gear not a 2:1. Even with the high reduction gear a 22X19 is a big prop to swing with 200 hp or less.

    Assuming all is OK with the 41A, bottom is clean etc....the engine needs to be freed up by 1,000 rpms WOT....that's 10" of pitch/diameter reduction.

    19X17 prop would reduce load by 600 +- rpms.

    Borrow a prop...start here IMO
     
  6. Diesel Jerry

    Diesel Jerry Captain

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    Agreed.
     
  7. m williams

    m williams Senior Member

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    Hi bill engine rpm test where done by photo tach I had the smaller prop on the boat for past 3 season this winter I was doing research on the propeller every prop shop I talked to to has Ben saying the 20x15 is way to small of prop for that engine and reduction gear size I am thinking that fuel injection pump may need to be looked at The boat original had the ms4 2.63 reduction gear and 22x21 way before I owned the boat I think I was getting rpm by propeller slipping
     
  8. BillD

    BillD Captain

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    Where the heck is Steve Law (mudhake) ? :D
     
  9. m williams

    m williams Senior Member

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    Ok here is a question did Volvo ever make a commercial duty engine where it would only max out at 3600 rpm I thought I read some where they did make it.

    Also this 3900 rpm was this for a outdrive version thanks mike
     
  10. steveinak

    steveinak Captain

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    I had both a inboard version and outdrive version of the 41A's both were supposed to turn up 3800. By the way i would never own another volvo.
     
  11. Reelin

    Reelin Member

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    Talk to Brian MacDonald.........no one knows Volvo's better.
     
  12. captjohn

    captjohn Senior Member

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    On the top of the pump, back near where it mounts to the engine, is a metal line with banjo fittings on each side going from what looks like a vacuum actuator on the pump to the intake manifold. It's basically a puff limiter. That actuator limits the amount of fuel going to the injectors until boost pressure builds. As boost pressure builds in the manifold pressure pushes down on that actuator, which increases the amount of fuel going to the injectors. Without a puff limiter you would have a fuel rich condition until boost pressure builds, resulting in black smoke. First thing to check, make sure the copper washers are present on the top and bottom of each banjo fitting, and that the bolts are tight. If that whole setup isn't working properly you will not hit your WOT RPM's. Also, in that actuator assembly is a shaft, that goes into the pump, that shaft can start to stick, causing the problem as well. I had this problem on one of my 41B's. I had to remove the pump, get it repaired, and reinstall it. But check the connections first, I did have a problem with one of those bolts coming loose, loosing pressure.
     
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  13. crabz

    crabz Senior Member

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    How much turbo boost? Does it have a boost gauge?
    also 41A's do not like to be over propped.
     
  14. crabz

    crabz Senior Member

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    Does it have this monkey motion linkage and solenoid on the elbow? I have never seen one in real life but I hear they can cause problems.
     

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  15. Genius

    Genius Captain

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    Crabz, what would that be for? That is not a mixing elbow with a shower is it?
     
  16. crabz

    crabz Senior Member

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    I honestly don't know! I had twin 41a's and neither had this option. And a single 41P that did not have it.
    Why would you have a butterfly flapper in the exhaust?
    This video at 1:48 shows the solenoid ?
     
  17. m williams

    m williams Senior Member

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    The exhaust elbow was changed before I bought it. I will start checking the injection pump. I don’t have a boost gauge on the engine how would I install one
     
  18. crabz

    crabz Senior Member

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    You can removed one of these plugs and drill and tap it for a fitting.
    Either a permanent installed turbo boost gauge or something inexpensive and temporary to just get a reading.
     

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  19. BillD

    BillD Captain

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    sure is, I bought two for the 41Pas...$400 maybe ?
     
  20. xbskt

    xbskt Captain

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    What signals the solenoid? Exhaust temp?
    I have to check the kids Volvo in the GM26 for this contraption.
     

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