Thermostat Blue Drain Plug - Different than Block?

Discussion in 'General Maintenance/Repair Questions' started by LUnaCY, Oct 13, 2018.

  1. LUnaCY

    LUnaCY Active Member

    206
    Aug 28, 2018
    Afton, MN
    310 Sundancer 2002
    Mercruiser 5.0 MPI Bravo III
    I have 2002 Mercruiser 5.0 MPI sterndrives. Winterinzed it today and had an issue with 1 thermostat drain plug. It seems the thermostat drain plugs are different size than the 3 block drain plugs. Does anyone have a part number for these? I purchased a replacement block drain plug and it didn't fit (18-4226). One of my tstat drain plugs works great on both engines, and the previous owner "made" the wrong one fit on the other engine.
     
  2. Espos4

    Espos4 Well-Known Member

    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    As far as I know, they are the same. HOWEVER, I have the same issue. My thermostat drain plug doesn’t fit well in the other spots.

    I just make sure to use the same plug for the thermostat housing and not try to put it into the water distribution fitting down low.
     
  3. LUnaCY

    LUnaCY Active Member

    206
    Aug 28, 2018
    Afton, MN
    310 Sundancer 2002
    Mercruiser 5.0 MPI Bravo III
    Figured it out. They are different on my boat. Manifold/thermostat drain plug is part #22_806608A1.
     

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