Evinrude 7.5 idle

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    james hobson


    Replies: 13
    Topics: 3
    #227142

    Will check compression any tips on how to check would be helpful

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    james hobson


    Replies: 13
    Topics: 3
    #227143

    Where is bleeder valve located on a 5.5 an 7.5 evinrude not familiar with this.

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    james hobson


    Replies: 13
    Topics: 3
    #227145

    Very true I will check compression any tips on checking would be helpful ,thanks

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    crosbyman

    Canada Member - 2 Years
    Replies: 1827
    Topics: 216
    #227149

    you needa common pressure meter that fits your spark plug holes …

    remove the sparkplugs,
    install the short hose of the meter
    crank the engine over 4-5 times and check compression value
    release the air pressure by pressing the purge valve on the meter repeat for second plug hole

    compare readings… should be within 10% or so and above 75-80 psi each

    utube is your friend…

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    • This reply was modified 2 weeks, 1 day ago by Avatarcrosbyman.
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    lloyd

    US Member - 2 Years
    Replies: 253
    Topics: 1
    #227151

    Compression test. First of all use a compression gauge that has been reliably used in the past. Perform the test on a motor that is Cold and Dry. Room temperature with no added oil in the cylinders. Warm motor may give false low results. Added oil in cylinders will give false high results. Remove both spark plugs and ground them to the engine block with ignition wires attached to avoid damage to the ignition system. Screw the compression gauge into the top cylinder and crank the recoil until the gauge reads as high as it will go. 3-5 quick pulls should be enough. Write down the comp reading for each pull. If the reading drops between the pulls you have a leak. If so correct the leak and repeat until you get consistent results. Repeat for bottom cylinder and write down the results.

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    crosbyman

    Canada Member - 2 Years
    Replies: 1827
    Topics: 216
    #227152

    see bleeder valve on a 5.5 but… looking at the 7.5 parts I can find……… I can’t see it ? maybe the 7.5 does not have one

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    james hobson


    Replies: 13
    Topics: 3
    #227498

    You say not to add any oil in cylinder when checking compression but when a two cycle is running does it not have oil in the cylinder would that not be more realistic conditions , right now I am only getting about 35- 40 on each cylinder, is it possible to run on one cylinder and check compression on other.

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    dave-bernard

    US Member - 2 Years
    Replies: 1281
    Topics: 17
    #227499

    with that compression may have a blown head gasket. pull the head and check.

    • This reply was modified 1 week, 3 days ago by Avatardave-bernard.
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    lloyd

    US Member - 2 Years
    Replies: 253
    Topics: 1
    #227508

    There is your answer. Low compression. Hopefully just a blown head gasket.

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    billw

    US Member - 2 Years
    Replies: 1383
    Topics: 42
    #227514

    Like Dave said, with those numbers, it may be a blown head gasket. 7.5s don’t have a metal ring for each cylinder, built into the gasket, like larger motors. I have a 7.5 myself, that I have to get around to doing a head gasket on. This sounds like a good thing for you to try. Be advised that when the head is off, you should check the head’s surface for machineed flatness; as they do tend to warp.

    All that being said, 35 to 40 psi???? It is a miracle that the engine even starts, never mind idles badly. Is it also hard to start?

    Long live American manufacturing!

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    fleetwin

    US Member - 2 Years
    Replies: 3598
    Topics: 35
    #227517

    Are you sure the gage reading is accurate? You might want to try a different gage…

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    james hobson


    Replies: 13
    Topics: 3
    #227556

    Will pull head and check , do I need to Torque head bolts to reAssemble what lbs.

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    crosbyman

    Canada Member - 2 Years
    Replies: 1827
    Topics: 216
    #227563

    see chart

    Torque-Chart-OMC-

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    • This reply was modified 1 week, 2 days ago by MumblesMumbles.
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    james hobson


    Replies: 13
    Topics: 3
    #227566

    No not hard to start at all seems to run good just won’t idle like I said low compression 30 -35 gauge I know is accurate pulling head tonight and will get new gasket will see where that takes me

    Mumbles
    Mumbles

    Canada Member - 2 Years
    Replies: 4652
    Topics: 260
    #227572

    I don’t think the spring loaded shock absorber on the drive shaft below the water pump has been mentioned here yet. If the prop has hit something hard, the spring will release and allow the shock absorber to expand, dragging on the bottom of the bearing carrier located below the water pump. The motor will run in this condition but the idle quality will be compromised. Can the motor be turned over easily by hand with the spark plugs removed?

    If you are going to service the impeller, it would be a perfect time to remove the carrier and inspect the bottom of it. Any contact between the two surfaces will be obvious. If a sprung shock absorber is detected, it can be pressed or pounded down to its original 6 11/16″ length. If the shock absorber is removed from the housing, the gearcase will more than likely have to be opened up to get the pinion gear back onto the shock absorber correctly. Meanwhile, let’s see what that head gasket looks like.

    Here’s a shock absorber and a housing with severe signs of rubbing.

    Shock-Absorber-2

    Shock-Absorber

    • This reply was modified 1 week, 2 days ago by MumblesMumbles.
    • This reply was modified 1 week, 2 days ago by MumblesMumbles.
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