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  1. #1

    Default Parsun 25hp "mechanic sound"

    Hi,

    First of all im a new user to this forum so if the thread is misplaced im sorry.

    I have a Parsun 25hp 4 stroke outboard engine(yamaha copy)
    wich have been working great untill a few days ago i noticed a strange sound if i go above half speed(around 3000rpm is around where the sound starts)

    I first tought maby its the valves? but should not the sound be at all times if the valves have to big clearence? but my next problem is where do i access the valves and in what position should the flywheel be in when i set the valves? I rather not take the boat out of the water to check this so i would really like to see exacly what i have to remove to be able to check the clearence, so i dont have to dismantle half engine top housing before i find it haha.

    and if this not is the problem? any suggestions what i could check?

    best regards

    C.S

  2. #2
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    3,470

    Default Re: Parsun 25hp "mechanic sound"

    http://www.parsun.us/
    You may be on your own as this is the first I have ever heard of the name brand. You may be able to sort out the parts here if you can find your model.

  3. #3

    Default Re: Parsun 25hp "mechanic sound"

    Hi,

    Thank you for reply, ye i think new brands have problem to get into the market but i was ready to try for 50% less price compared to mercury or yamaha.
    But all engines is good until you run into problem...
    I still have warranty but i wanted to check some things before i contact them. If i have to change engine. no more boating this summer :-(

    http://www.parsun.us/wp-content/uplo...ner-manual.pdf

    The manual gives the information what clearance should be. IN 0.15-0.25 EX 0.25-0.35 But i cant find what cover to remove to gain access to the valves.
    And also there is no information if there is any markings on the flywheel?! or how should you know when valves is fully open?
    guess i have to go down to the boat docks and get some hands-on experience.


    EDIT: Do you think the problem could be a big clerance? or do u suggest to look into something else?
    Last edited by Spoix; 07-28-2016 at 07:02 AM.

  4. #4
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    3,470

    Default Re: Parsun 25hp "mechanic sound"

    Pull the valve cover off of the head and rotate the flywheel clockwise with the spark plugs out, stick your finger in a spark plug hole and when you feel compression put a screwdriver in the plug hole and rotate the flywheel until the piston is all the way up. Then check adjust those two valve rockers it looks like the upper valve is the exhaust.

  5. #5

    Default Re: Parsun 25hp "mechanic sound"

    Thanks i will give it a try.

  6. #6
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    3,470

    Default Re: Parsun 25hp "mechanic sound"

    It looks like a major pain the get to the flywheel just have someone pull slow on the rope to put each cylinder TDC on the compression stroke.

  7. #7

    Default Re: Parsun 25hp "mechanic sound"

    ye but i think part of the flywheel is possible to access because there is a hole in the flywheelcover so maby i can turn it with a screwdriver. but i hope there will be markings aswell on the flywheel or else maby ill punch some dots to mark tdc for each cylinders for next time. ill report here when i have done it. but weather is to bad today.

  8. #8

    Default Re: Parsun 25hp "mechanic sound"

    Small update: did spend 45 min by the engine. cant find any marking on the flywheel and to remove the valve cover is a bigger job then i tought.
    Next thing i will do is to try to track the "bad sound" better when engine is running. it is possible to see the rocker arms from the oil filling plug so if the sound is coming from them it will be easy to hear.

  9. #9
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    3,470

    Default Re: Parsun 25hp "mechanic sound"

    You can use the poor mans stethoscope. Put your ear on the handle of a long screwdriver and touch different points of the engine. You should be able to listen to the individual rockers and bearings. Just be careful of moving parts the louder the noise the closer you are. It can be difficult with how close the moving parts are together but may point you in the right direction?

  10. #10

    Default Re: Parsun 25hp "mechanic sound"

    Ye possible worth a try. But outboard engines are so built in everything is very covered and close together as you say. But i will try it, also i will try to remove the oil filling plug and try to see and look down at the rocker arms. If i cant track the problem further i guess i have to make a oil change to see if that give me any clues.
    The oil looks clean on the stick so im guessing the compression still is good. no leaking exhaust from cyliner into crankcase.
    Last edited by Spoix; 07-29-2016 at 06:24 AM.

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