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Update on Chronic Overheat Problem 1998 90hp 2-stroke

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  • Update on Chronic Overheat Problem 1998 90hp 2-stroke

    I wanted to update on a chronic problem I was having on my 1998 90hp 2 stroke. I was having an overheat problem I could not solve. Water was running through my tell-tale (pee-stream), but engine would still overheat.

    I replace my thermostat. I replaced my pressure valve. I replaced my water pump. Nothing helped.

    I then removed my head cover and gasket. Cleaned it of all deposits. I removed the entire head and head gaskets. Cleaned all the water passages of deposits. I even removed the entire exhaust plates (I don't recommend this to anyone unless it's absolutely necessary!! God was on my side in that I only snapped 1 bolt, instead of all 18) and cleaned all those passages. Still Nothing helped!!!

    Finally I figured, I must have some partial blockage......there was NOTHING else it could be, right? Well wrong. When I took my lower unit off to start digging around the engine block from the bottom up, I also removed my (new) water pump. I noticed the housing the water pump sits on. It's actually part of the lower unit, and extends pretty far down into the lower unit and is incorporated with bearing to keep it pressure sealed. It's a housing plate, about 1" thick, that has channels on it. Your water pump kit sits directly on it. I noticed that mine looked a little corroded. The channels themselves were looking thinner than I thought they should (how would I know, there was nothing to compare it to). At this point I figured I better pass it on to an expert. My mechanic had to completely remove the internals of my lower unit to replace this part, but he did a fantastic job. Once I put everything back together, my water pressure was incredible!!!

    Now I can barely get the damn engine hot! I hope this helps someone out there. I have read every single overheat post that exists on the world wide web, and I never came across anyone with this problem. Good luck!!!

  • #2
    ???

    If it's the same housing on my 02 90 you do not have to disassemble the internals of the lower unit at all? Comes right out with an O-ring exposing the bearing u speak of. Good info either way.

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    • #3
      Just comes out the top...

      Yeah that plate just comes out the top and up the driveshaft. Shouldn't need to disassemble the guts of the lower unit. But this piece should be inspected at every waterpump change anyway.


      - Mike

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