New 9.9 Suzuki high pitch noise

Discussion in 'Boats, Motors, Trailers and Towing Rigs Forum' started by coast, Mar 10, 2018.

  1. coast

    coast New Member

    I tested out my new trolling motor today. There seemed to be a high pitch noise at low rpms right around trolling speed. The new Suzuki 9.9hp came with a 4 blade prop. I'm not sure what could be causing this so if anyone can help that would be much appreciated. Thanks!
  2. gungadin

    gungadin Well-Known Member

    If the high pitch noise appears to be coming from the leg, rather then the engine, I would suspect that the gears might be a little tight, or you are low on oil. If it is not broken in yet, change the leg oil into a clean container a little early and check for magnetic particles in the oil with a magnet. If it appears to be from the cowl area, check for something rubbing.
  3. Tyeeman

    Tyeeman New Member

    Get rid of the 4 bladed prop. I was told by the mechanic at Sheerwood Marine in Victoria that this was a problem that they had and only recomended the 3 bladed prop.
  4. coast

    coast New Member

    I took the prop back to Sherwood, they exchanged it for another 4 blade with a different pitch. Sure enough it maked the same annoying noise. I trolled with it today for 4 hours and it seemed to get marginally better as the day went on. I will use a 3 blade if necessary but would much rather have a 4 blade for trolling. I'm debating on filing the trailing edge a bit as I've read that this can solve the problem.
    Last edited: Mar 17, 2018
  5. Brando

    Brando Active Member

    I find it odd that it's the prop, mine does not do this and neither does a friends boat both running new 9.9s with the 4 blade as supplied.
  6. coast

    coast New Member

    I ran into a guy at the marina with the exact same new motor and prop. He has the same problem. Took the motor to Sherwood and everything tested out fine. I think it depends on the boat design. Apparently boats with pods have this issue more then others so that could be the case. The crappy part is it only makes the noise right at a certain trolling rpm so it's hard to diagnose. I'm not ruling out that it's not the prop but figure it would be a good starting point before I have to bring the motor back to the dealer.
  7. noluck

    noluck Active Member

    take the prop off and put it in the water, and just spin the shaft in gear
    Fishtofino likes this.
  8. bigdogg1

    bigdogg1 Active Member

    Noluck has a good idea. The problem with trying to replicate an issue at a shop is that test tanks can run motors but cannot put the same load as a vessel in water. Have seen this a few times where issues do not show up in test tanks but a water test showed immediately.
  9. trophywife

    trophywife Well-Known Member

    so a strange harmonic?
  10. coast

    coast New Member

    Yes it sounds more like a harmonic/pinging noise rather then squealing.
  11. coast

    coast New Member

    So I just spoke with the mechanic at Sherwood and he seems quite positive it's to do with the air intake. All I need to do is ream out a small hole a little bit, takes 5 minutes to do.
    BCI likes this.
  12. noluck

    noluck Active Member

    why not identify the problem before fixing what might not be the problem.

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