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  1. #1

    Default Water in Merc 90hp sport jet #2 cylinder

    I have a 1994 Searay Sport Jet with the Mercury Force 90 hp 3 cylinder outboard motor

    I had this thing running great then had the air/fuel a little fat 2 turns instead of 1 1/2 and ran it hard with four people in the boat (700lbs)

    then it died after half and hour and wouldnt restart.

    I pulled the plugs and it spun but water started shooting out of the #2 cylinder. (i still have good compression though 130, 128, 130 respectively)

    after I spun the motor to cough out the water I put the plugs back in and the motor wont spin. (it will hand spin but a brand new battery new relay and new cables arent enough to spin the motor freely. it will spin freely without the pugs in))

    heres my question: is my first step pull the head i should check the head for crack or to see if i blew the head gasket? or should i not bother because the something in the block is jacked?
    Last edited by w3Monkey; 05-05-2019 at 09:04 PM.

  2. #2

    Default Re: Water in Merc 90hp sport jet #2 cylinder

    I have a 1994 Searay Sport Jet with the Mercury Force 90 hp 3 cylinder outboard motor

    I had this thing running great then had the air/fuel a little fat 2 turns instead of 1 1/2 and ran it hard with four people in the boat (700lbs)

    then it died after half and hour and wouldnt restart.

    I pulled the plugs and it spun but water started shooting out of the #3 cylinder. (compression: 120, 128, 105 respectively)

    after I spun the motor to cough out the water I put the plugs back in and the motor wont spin. (i can hand spin the motor but a brand new battery new relay and new cables arent enough to spin the motor freely. it will spin freely without the pugs in)

    heres my questions: is my first step pull the head i should check the head for crack or to see if i blew the head gasket? or should i not bother because the something in the block is jacked?

  3. #3
    Join Date
    May 2019
    Location
    Big Sky MT
    Posts
    6

    Default Re: Water in Merc 90hp sport jet #2 cylinder

    Is there water still in the Cylinder?
    If you spin it with water in Cylinder and plug still in your going to break something....... Its called a Hydraulic Lock... bad Juju

    I would suggest pulling the head and taking a look...... none of other cyclinders have water?
    Whats the oil look like?

  4. #4

    Default Re: Water in Merc 90hp sport jet #2 cylinder

    Quote Originally Posted by camper8251 View Post
    Is there water still in the Cylinder?
    If you spin it with water in Cylinder and plug still in your going to break something....... Its called a Hydraulic Lock... bad Juju

    I would suggest pulling the head and taking a look...... none of other cyclinders have water?
    Whats the oil look like?
    I dont think the other cylinders had water. its hard to see because with this jet boat the outboard is in an i/O compartment.

    its a 2 stroke so its an oil gas mix so I dont think the block holds oil - correct?

  5. #5
    Join Date
    May 2019
    Location
    Big Sky MT
    Posts
    6

    Default Re: Water in Merc 90hp sport jet #2 cylinder

    Yep that would be correct... I would say most likely you are still getting water in there and that is causing it to not turn over when the plugs are installed.

  6. #6

    Default Re: Water in Merc 90hp sport jet #2 cylinder

    Quote Originally Posted by camper8251 View Post
    Yep that would be correct... I would say most likely you are still getting water in there and that is causing it to not turn over when the plugs are installed.
    I think you are right - I think I sucked water up and maybe slipped past the pistons and partially filled the powerhead? I took it out of the water and spun the motor with plugs out until there was no more water coming out. Put the plugs back in and it still wouldn't spin! Its a simple head so I popped it off and tilted the pitch of the motor in hopes of draining any water that slipped past the piston into the power head since there is no oil pan I cant drain it (to my knowledge) I ran the head to a machine shop and they said it wasnt cracked or warped. the machine shop operator said the gasket looked old and that it looked like water had traveled over it. as soon as the replacement gasket arrives i'll put the head back on. for now i sprayed Lucas assembly oil on the cylinders and pistons to discourage rust. Do you know of anyway to drain the power head of a two stroke? If not I'll just put the head back on and see if the motor will cough out any more water then try putting the plugs back in...

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