1997 Maxum 5.7L dies at idle after water in cylinders

Discussion in 'General Maintenance/Repair Questions' started by gica69, Aug 13, 2020.

  1. gica69

    gica69 New Member

    3
    Aug 21, 2018
    1997 Maxum Bayliner 5.7L Mercriuser Stern RWC
    5.7 mercruiser
    So this boat was running perfect and hasn't been used much.I took it off the coast one time this year in SO. Cal. on a fishing trip and ran perfect. Put it back in the parking lot and started it again 2-3 months ago again perfect. 2 weeks ago I tried to start it the night before a planned trip and it was locked up no go on the cranking. So the next day pulled the covers off and saw a lot of black liquid in the engine bay at the starter level. It was probably from the rain and my dumb ass forgetful mind to take out the drain plug. the starter planetary wheel was toast, changed the starter, new one fine. Opened the plugs up and had water in at least 5 cylinders maybe all could not tell. Changed the oil a few times. Now I can start but it dies at idle. If I keep it at 1200 Rpm it stays fine. before the water all perfect. Did a compression test and all between 160 and 170.
    Have no clue if the water got in because the risers suddenly got plugged up and back washed to the cylinders or rain water did it some weird way, but no idle, maybe rebuild carb needed. The question is why didn't it lock up on water?
    Raisers removal and inspect/replace needed, I know. But my main concern is the idle.
    So please help. Thanks in advance.
     
    Last edited: Aug 13, 2020
  2. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Probably water in your carb or under the dis. cap.
     
  3. gica69

    gica69 New Member

    3
    Aug 21, 2018
    1997 Maxum Bayliner 5.7L Mercriuser Stern RWC
    5.7 mercruiser
    Thought of the carb being dirty but how would water get in the carb? I don't think rain caused the water to get in the cyls. it may be a leak in the gasket to the manifolds and risers. Again after the salt water experience I flushed for 20 and again a month later, then it stayed until I discovered the hydro lock issue and water in bilge that second one could have been the rain. This post had same issue minus the hydro lock.
    https://www.thehulltruth.com/boatin...-2bbl-starts-but-will-not-idle-need-help.html
     
  4. gica69

    gica69 New Member

    3
    Aug 21, 2018
    1997 Maxum Bayliner 5.7L Mercriuser Stern RWC
    5.7 mercruiser
    So I took out the port side manifold and risers plus elbow. There is rust but not extra heavy.
     

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