squeaking/squealing 75 merc

  • sand_pike
    Posts: 51
    June 4, 2006 at 8:53 pm #1234272

    I’ve got a situation with my 2000 75 merc 2 stroke.
    After the motor is run at heavy load (ie wide open) for a period of 5-10 minutes, when I throttle down to troll there is a loud squeaking/squealing noise when the boat is in gear and in neutral. However, if I don’t run the thing wide open I can troll with it all day and not hear the noise. It’s after I push it a little harder the the noise pops up.
    The motor is pushing a alumacraft Mag 165 CS, I fog the motor every fall and change the lower unit oil.
    I changed the plugs and fuel filter last year.
    Any ideas where to start?

    birddog
    Mn.
    Posts: 1957
    June 4, 2006 at 11:34 pm #451298

    If it’s anything like my yammi it sounds like a belt squealing on a car?? I dealt with this noise and found out it was a vertical shaft coming off the bottom of the motor and running down into the lower. Silicon spray and it hasn’t done it since!! Here’s the link to which I replied with a pic a while back, your motor may have the same shaft?? Click here

    BIRDDOG

    sand_pike
    Posts: 51
    June 5, 2006 at 12:43 am #451307

    Thats exactly what it sounds like, a slipping/ squealing belt, thanks for the tip, I’ll give that a try.

    Quote:

    If it’s anything like my yammi it sounds like a belt squealing on a car?? I dealt with this noise and found out it was a vertical shaft coming off the bottom of the motor and running down into the lower. Silicon spray and it hasn’t done it since!! Here’s the link to which I replied with a pic a while back, your motor may have the same shaft?? Click here

    BIRDDOG

    sand_pike
    Posts: 51
    September 7, 2006 at 1:30 am #475919

    bump…
    I’ve sprayed the heck out of the shaft with silicone,
    with limited success. I thought I had cured it, but it was back, and worse this past weekend.
    Any additional ideas, thoughts?

    gary_wellman
    South Metro
    Posts: 6057
    September 7, 2006 at 1:58 am #475943

    If you have a shaft that is squealing, then you have a bad bearing. No lube or grease or silicone spray is going to fix that. You need to have it serviced and repaired.

    Call a shop and talk to them about it is my recommendation.

    crossin_eyes
    Lakeville, MN
    Posts: 1377
    September 7, 2006 at 3:34 am #475994

    My brother in law and I both run 75 Merc 2 stokes. Mine is a 1998 and his is a 2000. he had the same thing happen and it was actually the warning horn going off, but sounded not at all like mine and very much like a skeaky belt. I’d have that looked at. it was a quick and inexpensive fix.

    Good Luck.

    Mike

    sand_pike
    Posts: 51
    September 8, 2006 at 2:53 am #476393

    OK, guess i’ll have it checked out.
    thanks

    sand_pike
    Posts: 51
    April 29, 2007 at 11:51 pm #566009

    Bump this thread,
    I had my 75 merc in the shop, bushing lubed and re-aligned.
    Did not fix this sqealing problem. My dealer told me there is one other cause for this noise and merc is aware of it.
    Apparently at WOT the #3 cylinder can lean out and starve the mains for oil, that squealing noise you are hearing is the mains spinning, ummm not good…..

    The “solution” to this is to put a fatter jet in the #3 carb, I’m not sure what good that will do????
    I’ll be headin back to the dealer this week to talk the tech,
    probably a call to merc as well.

    Question???
    Could I just put a quart of oil in my tank each time a fill up?( I did it during break in)
    I’d probably foul some plugs, but better than spinning the mains.
    I can’t afford to have this motor grenade on me.
    Anyone know if adding oil to the tank would hurt anything else?

    gary_wellman
    South Metro
    Posts: 6057
    April 30, 2007 at 2:45 am #566089

    Did the bearings get replaced?

    sjh62
    On the border-Trempealeau
    Posts: 69
    April 30, 2007 at 2:46 am #566092

    That squealing noise is a bearing on the bottom of the powerhead.A friend of mine has a 1997 90HP that does that.Only after extended full-throttle running in warmer weather.Could be a design flaw that does not let enough oil to that bearing at full load.That is what one Merc tech told him.

    If you pulled the powerhead,it is the bearing assembly that the driveshaft goes into.Have not heard of any that grenaded,so he says”party ’till it pukes”.I heard it twice,and it can be hard to pinpoint.His has been doing that for awhile now.

    It is a roller bearing,so it could sieze if it got too hot.Not sure what extra oil will do to help,but couldn’t hurt.

    sand_pike
    Posts: 51
    May 1, 2007 at 1:15 am #566456

    Quote:

    Did the bearings get replaced?


    shaft bushing that goes into the tail housing was replaced along with the impeller, did not fix the problem. My dealer was pretty straight with me, merc rep told him it could be one of two things, the bushing or the mains squealing, looks like it’s the latter.
    IMO , if your main crankshaft bearings are making that kind of noise, it cannot be good.

    gary_wellman
    South Metro
    Posts: 6057
    May 1, 2007 at 12:12 pm #566561

    Not trying to make a mountain out of a mole hill, nor scare you. But the thought of main bearings squealing or “spinning”……makes me cringe!!!!!

    2-stroke motors are tough…….VERY tough, but they can’t handle loosing a main bearing. I wish you the best of luck trying to get this resolved.

    sand_pike
    Posts: 51
    May 3, 2007 at 12:08 am #567264

    I agree, I’m going to try fattening up the high speed jets in the one offending carburator. Worth a shot

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