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Thermostats

Discussion in 'Chris Craft Connies, Commanders & Catalinas' started by timvail, Aug 4, 2016.

  1. timvail

    timvail Senior Member

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    Mar 15, 2010
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    Location:
    georgian bay penetanguishene
    I have a 1980 Chris Craft 350 Catilina refurbished. ( 6 yrs now) The port engine last week started to run about 10 degrees above normal operating temp of between 140 to 165. The engines are the original 350q closed cooling system. I located a manual which shows the thermostat just in front of the heat exchanger. Removed the top of housing and no thermostat. Checked the pressure tank end from raw water and no thermostat there either. Anyway I removed the heat exchanger, pressure tank and oil cooler to be boiled and cleaned. Ready to install today. The manual says I need a thermostat ( low profile ) one to be fitted in the thermosat housing in front of the heat exchanger. The local marina mechanic people say the thermosat should go in the pressure tank intake.
    Soooooo, since the engine was running fine without the thermostat iam thinking of re installing the above parts and seeing what happens first before I do anything else.
    Any thoughts or experience from anyone in the southern part of the country where closed cooling systems a more common. Where iam we are only able to boat 5-6 months of the year. Thanks for any replies.
  2. Capt Ralph

    Capt Ralph Senior Member

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    A closed cooling system should run from 160 to 180 degrees.

    Without thermostats you engines may not be running correctly and 10 degree swings could be a common occurrence. IE; the lead engine in an old syncro operation.
  3. timvail

    timvail Senior Member

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    Thanks rcrapps for your reply. The manual says operating temp should be between 140 and 165. The starboard engine runs at a constant 150.
  4. Capt Ralph

    Capt Ralph Senior Member

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    Interesting,, I would think 140 to 165 is the perfect temperatures for a complete raw water cooled engine.

    Still, without any thermostat, the temps could move around a bit, IMO.

    BTW, is there a stat in the other engine?
  5. timvail

    timvail Senior Member

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    Location:
    georgian bay penetanguishene
    Yes I agree, my old ride was raw water cooled and did operate in that range. Closed cooling is something I know little about. Prior to the past 2 weeks it rN at a constant 160. Starboard runs at a constant 150. The manual says I need a low profile thermostat which iam trying to locate through marina now, but today will be installing the items I removed and had cleaned.
  6. timvail

    timvail Senior Member

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    Location:
    georgian bay penetanguishene
    Reading my mind. Once I install the heat exchanger and oil cooler and put things back together iam going to see if the other engine has a stat in it.