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  1. #1

    Default ealry 60's Chrysler 318 cooling problems

    Hello,
    I have a recently rebuilt early 60's model Chrysler marine 318 with a fresh water cooling system. This particular engine has the thermostat housing with the choke t-stat and pressure relief disc. The engine is running hot, and I can't seem to figure out why. I would like to replace the t-stat housing as it is corroded, but I cannot find any of this type. I have tried to bleed all the air from the system, but that has not helped. It is hard to tell if I am getting good cooling in the heat exchanger or proper circulation. The fresh water pump dual impellers were ok when installed recently, and it seems I am getting good flow on the seawater side.

    I am running out of ideas. Does anyone have any suggestions?

    Thanks in advance!
    Tony

  2. #2
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    5,576

    Default Re: ealry 60's Chrysler 318 cooling problems

    Ayuh,.... My 1st guess is the raw water pump, ain't pumpin',.....

    Pull the raw water feed hose of the HE, 'n See if it's pushin' water,....
    Then make sure the used raw water can escape,...
    Any Grease is Better,... Than No grease at All....

  3. #3

    Default Re: ealry 60's Chrysler 318 cooling problems

    Quote Originally Posted by bondo View Post
    Ayuh,.... My 1st guess is the raw water pump, ain't pumpin',.....

    Pull the raw water feed hose of the HE, 'n See if it's pushin' water,....
    Then make sure the used raw water can escape,...

    Thanks for the response!

    Yesterday I pulled the seawater pump and checked the impeller. All good…
    I also flushed from the downstream side of the pump through the HX and out of the exhaust. All lines are clear…

    When I ran the boat in the water Friday, I could see the water swirling in the suction strainer for the seawater pump, but I will confirm that again today with a hose.

    I also plan to pull the impellers of the fresh water pump (it has 2 in a single pump housing). They were good when I installed them, but after several weeks of troubleshooting, I suppose it would be good to check them since I know that I had lots of air in the closed loop system.

  4. #4
    Join Date
    Mar 2015
    Location
    Toledo Ohio
    Posts
    11

    Default Re: ealry 60's Chrysler 318 cooling problems

    Change ALL the antifreeze in the closed system with a 60% water and 40% antifreeze mix. ......Ray

  5. #5
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    5,576

    Default Re: ealry 60's Chrysler 318 cooling problems

    When I ran the boat in the water Friday, I could see the water swirling in the suction strainer for the seawater pump, but I will confirm that again today with a hose.
    Ayuh,.... Start the motor, then pull the raw water inlet hose, off the heat exchanger, 'n hold it pointed straight Up,....
    At idle, the stream of water should rise 5" or 6", before it topples over upon itself,....

    Any vacuum leaks in the raw water pump, or the pipin' leadin' into it, will cause air to be sucked into the coolin' water,.....
    Any Grease is Better,... Than No grease at All....

  6. #6

    Default Re: ealry 60's Chrysler 318 cooling problems

    Got any photos to share?

  7. #7
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    2,921

    Default Re: ealry 60's Chrysler 318 cooling problems

    Quote Originally Posted by bondo View Post
    Ayuh,.... Start the motor, then pull the raw water inlet hose, off the heat exchanger, 'n hold it pointed straight Up,....
    At idle, the stream of water should rise 5" or 6", before it topples over upon itself,....

    Any vacuum leaks in the raw water pump, or the pipin' leadin' into it, will cause air to be sucked into the coolin' water,.....
    A leak in the gasket of the cleanout port on the strainer a common cause of overheat problems. A mason jar seal with the tab cut off is a good replacement for some strainer cleanout ports. Some cleanout ports can be installed "kittywampus" and cause vacuum leaks and overheating.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280
    1972 22ft Bristol
    Honda 7.5HP 4 stroke Long shaft

  8. #8
    Join Date
    May 2013
    Location
    Western Wahington
    Posts
    51

    Default Re: ealry 60's Chrysler 318 cooling problems

    Quote Originally Posted by asrotolo View Post
    Hello,
    I have a recently rebuilt early 60's model Chrysler marine 318 with a fresh water cooling system. This particular engine has the thermostat housing with the choke t-stat and pressure relief disc. The engine is running hot, and I can't seem to figure out why. I would like to replace the t-stat housing as it is corroded, but I cannot find any of this type. I have tried to bleed all the air from the system, but that has not helped. It is hard to tell if I am getting good cooling in the heat exchanger or proper circulation. The fresh water pump dual impellers were ok when installed recently, and it seems I am getting good flow on the seawater side.

    I am running out of ideas. Does anyone have any suggestions?

    Thanks in advance!
    Tony
    Hey Tony, any luck with your overtemp issue. I’m having a similar problem and was curious if you found a solution.

    Russell

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