Search results

  1. T

    Drain Plugs for 1999 Mercruiser 4.3 Thunderbolt 6 cyl

    Thanks for your input Nola Mike! This is what I wanted to hear! I can tell for a fact that square plug has never been unscrewed in this old boat's history. It is rusted on and if I crank on it I"m gonna break something and be back to square one with a whole new issue. At this point I've...
  2. T

    Drain Plugs for 1999 Mercruiser 4.3 Thunderbolt 6 cyl

    Thanks for all of the info and additional tips! Again, I have already removed two drain plugs from each side so that takes care of finding the ones on each side of the block down low (right?)and will attempt to get that square one loose without cracking something. Also, this is a fresh water...
  3. T

    Drain Plugs for 1999 Mercruiser 4.3 Thunderbolt 6 cyl

    Thank you! Yes I have disconnected the big "U" hose and there is no water in anything that I have drained (I poked up into the 4 holes). But, I am pretty sure I won't be able to get that square plug loose and I know it's never been done. My mechanic told me to tilt the boat nose down while...
  4. T

    Drain Plugs for 1999 Mercruiser 4.3 Thunderbolt 6 cyl

    Thank you for your quick response and details. I am attaching another pic "close-up" of the square brass plug I believe you are referring to. Is this the 5th plug? If so, it's gonna be a ***** to get off. I really don't think it has ever been unscrewed so maybe it's not mandatory but I will...
  5. T

    Drain Plugs for 1999 Mercruiser 4.3 Thunderbolt 6 cyl

    I am getting mixed messages and info on the # of drain plugs on my 1999 Mercruiser Thunderbolt I/O 6 cylinder. There are two on each side but I have spent over an hour looking for something on the front and it is not there. Is it possible that the 1999 doesn't have a drain plug for water in...
Top