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I kinda hate Chrysler 360's (overheating issue)

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  • I kinda hate Chrysler 360's (overheating issue)

    I'm stumped with the Mako 26.

    FWC motors.

    1 runs at 150-160 idle, risers are around 105/110

    Other Would slowly just climb up and up and up.

    I pulled the thermostat and ran it sans thermo now it runs 150-160ish

    The odd part is the risers on the hot motor were about 5-10 degrees warmer with the port riser spiking between 115 and 130 (vs the other motors 110 pretty steady). pulled the side plugs and they look a bit munged up, but not complete passage blockage (i would have to split them to check but that would require ordering new gaskets) i don't think.

    Thoughts? Other than yanking them and dropping a pair of 5.7's in the stupid boat. []
    1975 Mako 26 Inboard[br]1976 Mako 23 Inboard[br]1984 Rhodes 19[br]Padanaram, MA

  • #2
    Sounds like a raw water flow issue to me. Heat exchanger, raw water pump, intake strainer clogged would be things I'd check.
    [br]***[br]\'82 Ski Nautique - Lake Martin, AL[br]\'80 236IB - Lake Martin, AL[br]\'03 Pursuit 2670 - Destin, FL

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    • #3
      couple thoughts off the cuff:

      I would definitely deep dive the raw water side; most likely suspect, although possible the fw circuit could have issues.

      Does the boat have a "crash valve" (i.e. raw water intake diverter valve to pump out the bilge)? I have left mine open and it sucked air and heated the engine

      Pull the hose downstream of the raw water pump and check flow. maybe compare to good side engine's flow?

      How old are the risers? do you have a reliable history on them? These are always the achilles heel....

      I would be disinclined to suspect the fw side of the system other than the recirculating water pump..but those are typically metal vaned and the failure points are the bearing or seals....even with fw good flow, a restricted raw water channel on one side riser would run that side hot.

      Hope you figure it out Ted~

      Don
      [br]DonK[br]Boca Raton, FL[br]1979 236IB: \'The Fish Tank\'[br]1979 Backcountry 18 \'Boner\'[br]<>< <>< <>< <>< ><> J[br]Redneck Troubleshooting:[br]1) If it moves, but ain\'t supposed to, use Duct Tape[br]2) If it don\'t move, but supposed to, use WD40[br]3) If that don\'t fix it, it\'s electrical![br]

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      • #4
        Just a random thought, the raw water pump pulley has a wobble to it when running, I wonder if its sucking air past the shaft.
        1975 Mako 26 Inboard[br]1976 Mako 23 Inboard[br]1984 Rhodes 19[br]Padanaram, MA

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        • #5
          quote:


          Originally posted by DestinBound


          Sounds like a raw water flow issue to me. Heat exchanger, raw water pump, intake strainer clogged would be things I'd check.



          Intake strainer and sea strainer are in great shape (the boat has the $500 combo sea strainer/thru hulls) heat exchanger I backflushed and seemed to have plenty of flow.

          Risers or raw water pump are what I'm down to.

          I'm gonna pull the raw water pump when it cools down a bit (its 90 + 90% humidity at the marina right nwo) later and tear it down at home.
          1975 Mako 26 Inboard[br]1976 Mako 23 Inboard[br]1984 Rhodes 19[br]Padanaram, MA

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          • #6
            anything that causes decreased flow through the raw water side,inlet or outlet,will increase temps

            this is why I'm a big fan of water pressure gauges, they will show issues in the raw water side of the system WAY before they show up on a temp gauge
            76 25 \"Aenigma\"[br]73 17[br]Richland/Long Beach, MS[br]http://www.classicmako.com/forum/topic.asp?TOPIC_ID=14182[br][br]17 project[br]http://www.classicmako.com/forum/topic.asp?TOPIC_ID=56176

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            • #7
              Not the pump, its nice and tight on the bench. Time to backflush the oil cooler and replace the hose from the oil cooler to the pump (its a bit sketchy)
              1975 Mako 26 Inboard[br]1976 Mako 23 Inboard[br]1984 Rhodes 19[br]Padanaram, MA

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              • #8
                I fought a cooler, that I thought was clean, years ago. Rawwater had started to come apart and logged pieces in the cooler. I had the cooler cleaned by a shop, but that still didnt help. Replaced the cooler and temps went back where they belonged.
                quote:


                Originally posted by TPG


                Not the pump, its nice and tight on the bench. Time to backflush the oil cooler and replace the hose from the oil cooler to the pump (its a bit sketchy)



                1982 Whaler Montauk 90HP( sold)[br]1977 25 Mako CC 225HP

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                • #9
                  quote:


                  Originally posted by rustyolddad


                  I fought a cooler, that I thought was clean, years ago. Rawwater had started to come apart and logged pieces in the cooler. I had the cooler cleaned by a shop, but that still didnt help. Replaced the cooler and temps went back where they belonged.

                  quote:


                  Originally posted by TPG


                  Not the pump, its nice and tight on the bench. Time to backflush the oil cooler and replace the hose from the oil cooler to the pump (its a bit sketchy)




                  Chrysler coolers seem to be easy to inspect though. End plates are massive. Haven't gotten back to this because I'm dealing with a starting issue on this motor currently. (I think its solenoid, we'll see when I jump it later)
                  1975 Mako 26 Inboard[br]1976 Mako 23 Inboard[br]1984 Rhodes 19[br]Padanaram, MA

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                  • #10
                    One side can run hotter if you have a lean condition on one or more cylinders on that side. Could be an intake problem. This would be a very low probability problem. Just putting it out there if you think the cooling circuits are ok.

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                    • #11
                      quote:


                      Originally posted by Headcase


                      One side can run hotter if you have a lean condition on one or more cylinders on that side. Could be an intake problem. This would be a very low probability problem. Just putting it out there if you think the cooling circuits are ok.



                      Interesting. It is a carb'd motor. Not sure how I'd troubleshoot that, my first rodeo with carbs.

                      Figured out my starting issue.


                      1975 Mako 26 Inboard[br]1976 Mako 23 Inboard[br]1984 Rhodes 19[br]Padanaram, MA

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                      • #12
                        Thermostat. Freaking thermostat. Temp wanders between 140 and 160 so I still have air in the system. I'll fix that after I figure out where this heat exchanger is leaking from. []
                        1975 Mako 26 Inboard[br]1976 Mako 23 Inboard[br]1984 Rhodes 19[br]Padanaram, MA

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                        • #13
                          Topped off the heat exchanger and ran it in the slip again. Parks at 160, jump it up to 2k for a bit then back off to idle, doesn't jump up anymore in temp. Need to go run it with a load to see if its happy.
                          1975 Mako 26 Inboard[br]1976 Mako 23 Inboard[br]1984 Rhodes 19[br]Padanaram, MA

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                          • #14
                            So now that I've run them a bit in the slip, port motor runs 160-165, stbd runs 170 solid. I have a feeling I probably need risers and elbows on the stbd motor. Bonus from work in a week to two, I'll probably do them for sanity sake. Hopefully this easterly dies out so I can run the boat to see if its happy.
                            1975 Mako 26 Inboard[br]1976 Mako 23 Inboard[br]1984 Rhodes 19[br]Padanaram, MA

                            Comment


                            • #15
                              So now that I've run them a bit in the slip, port motor runs 160-165, stbd runs 170 solid. I have a feeling I probably need risers and elbows on the stbd motor. Bonus from work in a week to two, I'll probably do them for sanity sake. Hopefully this easterly dies out so I can run the boat to see if its happy.
                              1975 Mako 26 Inboard[br]1976 Mako 23 Inboard[br]1984 Rhodes 19[br]Padanaram, MA

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