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winterizing closed cooling system

Discussion in 'Boats and Motors' started by picktowndad, Aug 12, 2008.

  1. picktowndad

    picktowndad share the joy of fishin

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    I have a 1985 170 H.P. mercruiser IO closed system. Ive checked the threads here with no luck. Can anyone help me with this unit? Also does anyone know a good mechanic in Central Ohio that will work on this unit. It is ok now but dont want to be stuck later.
    Thanks
     
  2. I have a 83 mercruiser 470, it's a four cyl. closed cooling, what info you looking for? For winterizing I pull the caps on the heat exchanger and drain the fresh water out, also lower the out drive to drain out.As for the closed side of it I check the freeze point.
     

  3. picktowndad

    picktowndad share the joy of fishin

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    Are the caps on the end of the heat exchanger? Is that the only item that needs drained? I ve had a io before and had to drain the block, manifolds and lower the lower unit. Thank you for your response
     
  4. There are plugs on the heat exchanger for draining. One is for the sea water and the other is for the anti freeze. By draining with plug you do not need to remove the end caps of heat exchanger. If you do pull the end caps do not overtighten when you reinstall or you will crack them. (this I know for sure) I believe there is one other plug that you need to drain on that unit. Cannot recall it's location. PM me for reminder and I can look in manual.