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Thread: Engine Noise coming off the Throttle

  1. #1
    Join Date
    Jul 2020
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    Dallas/Fort Worth
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    75

    Default Engine Noise coming off the Throttle

    Hello all,

    I have a weird noise coming from the engine when I accelerate and come off the Throttle. It just started with nothing out of the ordinary happening. It's worth noting that I just found a lot of fishing line caught in my prop and removed all of it. Not sure if it can get deeper into the spline or cause issues, etc.

    Anyway, here's the video. Listen every time I come down from accelerating, you can hear what sounds like a metal whirring sound perhaps. Hopefully I might find some insight here and possiblity figure out what I need to do to resolve.

    https://vimeo.com/580542603

  2. #2
    Join Date
    Jul 2006
    Location
    Raystown Country, PA
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    Is it in gear when you are doing that?

    Do you have a stainless prop?

    The forward gear on most outboards has a taper on one of the gear faces, so that the propshaft can spin faster than the gears in forward. When it does that it will make a clicking ratchet sound as it does. I think you are hearing that ratcheting. When you shoot the rev, the prop gets some momentum, and when you let up it passes the gears up and clicks a few times.

    Check the lower unit lube level and make sure you did not get any leakage or water infiltration from the line in the seal. 90% of the time line on the shaft will NOT cut the seal, but it can create a gap while its on there that lets oil out, and water in. Make sure the lower unit is full until it runs out the top plug, with clean marine gearlube
    Last edited by Moser; 07-29-2021 at 10:38 AM.
    1992 Tracker Party barge 24 (new deck, carpet and interior, 2019)
    1996 Mercury 115 ELPTO
    1983 Sea Nymph FM171 Striper
    1985 Johnson 70 J70ELCO

    Raystown Country, PA

  3. #3
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    Jul 2020
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    I actually just changed out the entire lower unit oil this morning. It was pitch black with "discolored spots" in the oil... Maybe that indicates there was water in there?

    I also noticed my anode was missing and the screw was just bouncing around inside the little rubber cap. Maybe that was the sound?

    To answer your original question, the boat was in gear and the prop appears to be stainless yes. I am going to try running it again with the new oil and loose bolt removed. It very well could have been that bolt rattling around...

    How do I find out the correct anode part I need? Just call dealer when it opens?

  4. #4
    Join Date
    Feb 2014
    Location
    Boat at Lake of the Ozarks Missouri
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    709

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    Hey J:

    The anode can be identified by going to Mercury's site on-line and looking for the
    engine tab, then go to engine parts and type in you engine serial number.

    Some where in that listing will be the anode part number. I would ask the dealer
    if they have the part and costs but also google it and look for a mail order outlet that
    sells Mercury parts.

    If possible, I'd stay with the OEM Mercury part.

    Let us know if the rattle was from the loose bolt on the anode, ( I assume the anode went missing ? )
    however I'd be curious about any fishing line damage and pull the prop to check the seal.

    Based on your description of the old fluid it sounds like it hasn't been changed in many years.
    Is that a used engine ? - have you ever had the lower unit lube changed since ownership ?

    If the seal is letting water get into the lower unit, it would be best to know now rather than
    out on the water when if locks up.

    Here is the link for Mercury

    https://www.mercurymarine.com/en/us/
    Last edited by Captain Tony; 07-29-2021 at 09:29 AM. Reason: Update info
    Captain Tony
    2005 Summit by Triton - 220T Platinum 3Log
    2005 115HP Mercury Optimax - 228 Marine Master Trailer
    St. Louis & Lake of the Ozarks, MO.

  5. #5
    Join Date
    Jul 2020
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    Dallas/Fort Worth
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    Default

    Quote Originally Posted by Captain Tony View Post
    Hey J:

    The anode can be identified by going to Mercury's site on-line and looking for the
    engine tab, then go to engine parts and type in you engine serial number.

    Some where in that listing will be the anode part number. I would ask the dealer
    if they have the part and costs but also google it and look for a mail order outlet that
    sells Mercury parts.

    If possible, I'd stay with the OEM Mercury part.

    Let us know if the rattle was from the loose bolt on the anode, ( I assume the anode went missing ? )
    however I'd be curious about any fishing line damage and pull the prop to check the seal.

    Based on your description of the old fluid it sounds like it hasn't been changed in many years.
    Is that a used engine ? - have you ever had the lower unit lube changed since ownership ?

    If the seal is letting water get into the lower unit, it would be best to know now rather than
    out on the water when if locks up.

    Here is the link for Mercury

    https://www.mercurymarine.com/en/us/
    Yes, I was able to locate an anode and should be here today. I've changed the lower unit oil in the past myself, I would ballpark 6 months ago I think? I feel like I did it before this boating season started.

    I did remove the prop and find additional fishing line which I also removed. Not sure if I need to remove the lower unit to check the gears or anything like that. The boat still seems "a little rattley" but I will drive it here in a little while to check it. Also, I noticed that when I first started the engine this morning to run it with the new gear lube, I went to put it in gear and go forward(with water ears attached), the engine died. I turned it back on and it was fine after that but I notice sometimes when trying to accelerate, the engine will die at first. Not sure what causes that.

  6. #6
    Join Date
    Jul 2006
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    Raystown Country, PA
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    Black is good, it just means old. If it is not milky or actually has water in the lower, the seal survived ok. I have a tester now, but in the past, I would turn a regulator way down to just a puff of air and put 3 or 4 pounds of air in the top hole of a drained lower unit to see if it would hold the pressure. you can rig up a pump hose on a air gun to put it in with. If you want to get carried away put a ball valve and a gauge in the hose, charge it with 6 7 psi, close the ball valve and see if it holds it.

    In this case I would fill it, take a 2 hour cruise and then check it for water, if it's good, all is well.

    I would search by horsepower and serial range at boats.net to find the anode number, then look for a used one on ebay.

    Whats the engine HP and serial number, we will find you one? I may have one here, actually, I give great discounts to forum peeps.
    1992 Tracker Party barge 24 (new deck, carpet and interior, 2019)
    1996 Mercury 115 ELPTO
    1983 Sea Nymph FM171 Striper
    1985 Johnson 70 J70ELCO

    Raystown Country, PA

  7. #7
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    Jul 2020
    Location
    Dallas/Fort Worth
    Posts
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    Here are some pics of the whole endeavor. The fishing line, the plug that came out of the lower unit drain and the actual oil. Definitely didn't appear milky white.
    https://photos.app.goo.gl/dNYBhyt1a896kb9C8

  8. #8
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    Jul 2020
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    Dallas/Fort Worth
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    So the propeller does not seem to be making any noise as I can spin it pretty quickly and freely without it making any sound.

    If I had to describe the noise that I'm hearing, I would describe it as noisy lifters in an engine. I did hear it again when I just drove the boat from a dock to the trailer, and the sound seemed to be persistent with various fluctuations based on speed

    Can this be a result of water in the fuel, as I was thinking about changing out the water fuel separator but haven't gotten to it this season.

  9. #9
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    Jul 2020
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    Here is a link to video of the sound happening. It only seems to be MORE noticeable when in gear at lower RPMs but still at higher ones. The engine just sounds rougher.

    https://vimeo.com/580988818

  10. #10
    Join Date
    Jul 2006
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    Raystown Country, PA
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    It sounds like something under the hood, but it is so hard with video to hear what you are actually hearing. What was the stuff on the pluig? If it is fine metal pieces, the lower unit needs a pro to look at it. I dont see anything in the oil or with the line on the shaft to say there is something major wrong. I see oil like that and line on shafts every week, and the lower units are fine. You do have a clicking for sure, double check all your parts and pieces form when you put it back together, make sure everything is back in the right spot. Pull the bottom plug out again and see if there is metal on the magnet now. If there is, something is up and the sooner you get it to a pro, the less it costs.

    What lube did you use for the lower?

    If you heard the noise before you draqined the lower, something is wrong and it needs a pro. Lower units a intricatre assemblies, and you need the right equipment to disassemble and reassemble them correctly, I take all but the simplest ones to a different shop, I don't do them here.
    1992 Tracker Party barge 24 (new deck, carpet and interior, 2019)
    1996 Mercury 115 ELPTO
    1983 Sea Nymph FM171 Striper
    1985 Johnson 70 J70ELCO

    Raystown Country, PA

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