Running Cold

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  • larry.brand
    Member
    • Jun 2010
    • 1

    Running Cold

    Hello. We have a situation; our Atomic 4 does not warm up... it starts at 100 and the needle rises a just bit when running hard. Here is what I have done so far
    1) the original Holley t-stat was removed and tested. It starts opening at 152 and is completely open at 173 (it’s great to have access to lab equipment!).
    2) I can force the temp higher by partially closing the raw water intake
    3) I can not find any leaks in the system.
    4) I have check and played around with the timing and it does not seem to have an effect
    4) I tried to ohm out the temp sensor but I could not get a consistent reading. This was done 2 ways, one with the raw water wide open and once with the raw water partially closed. In both cases I could not get a reading. I suspect that is done to user error because the gauge will rise when the water flow is closed.
    5) a new manifold was installed a couple of years ago and the issue seems to coincide with that repair.
    6) all hoses are new with the mainifold repair
    7) the amount of water exiting the boat with the exhaust appears normal, ie no changes
    8) a new MM carburetor was installed (long story for another time!)
    The engine runs fine... a bit rich sometimes.
    Any ideas?
    Thank you,
    Larry
    ‘79 Tartan 30
  • Al Schober
    Afourian MVP
    • Jul 2009
    • 2006

    #2
    Hi Larry,
    First, welcome to the forum. There's a source of advise here - only you can decide whether it's good or bad.
    How nice to get a 'won't warm up' issue. Most of the temperature issues are with overheating. As to a problem, I don't think you have one. I had a Tartan 30 for many years, and ran the engine cool.
    First, I suspect you're getting more coolant flow with the new manifold. The old one was likely clogged and acting like a partially closed intake valve.
    How were the springs on the thermostat? The springs act to pull it closed, and weak springs are perhaps allowing the flow to force it open. Doubt if it's upside down - wouldn't open at all!
    Where is your temperature sender? Stock location on the fwd end of the head? Just for fun, you may enjoy playing with an infra-red thermometer and seeing what temperatures are actually on the block and head.
    As for running rich, I recommend the adjustable main jet. https://moyermarine.com/product/carb...ly-fcar_07_58/
    Last edited by Al Schober; 07-16-2018, 12:00 PM. Reason: add link

    Comment

    • ndutton
      Afourian MVP
      • May 2009
      • 9601

      #3
      I assume you have raw water cooling. I'll second Al's advice to get an IR temp gun (cheap at Harbor Freight Tools). Earlier this year I was invited to test Moyer Marine's new thermostat and one of the tests may be helpful to compare your temp measurements. I've attached two pdf's, one with the results of my raw water cooling test with the new thermostat, the other is a blank chart for your use.

      A4 temp worksheet RWC with Tstat.pdf

      A4 Temp Worksheet.pdf

      Please notice the measurement at the head cantilever below the thermostat most closely mirrors the gauge temp because the sender is in the same coolant pocket. Comparison of your numbers may lead us to better conclusions.

      The test protocol was with the engine in forward gear tugging against the dock lines, 1700 RPM, first measurements 5 minutes after a cold start.
      Neil
      1977 Catalina 30
      San Pedro, California
      prior boats 1987 Westsail 32, 1970 Catalina 22
      Had my hands in a few others

      Comment

      • joe_db
        Afourian MVP
        • May 2009
        • 4474

        #4
        My engine is very similar. I have to run it at full power for some time in warm water to budge the temp past 120. When I was experimenting with FWC I could easily get 180-190 or more and the resulting heat in the boat was not pleasant on a hot day.
        I know all the theories of why this is not good, but practically the engine seems to be just fine, no sticky valves, and the oil gets hot.
        Joe Della Barba
        Coquina
        C&C 35 MK I
        Maryland USA

        Comment

        • goodoldboat
          Senior Member
          • May 2017
          • 130

          #5
          IR gun

          i have purchased the IR gun and plan to use it this weekend , as I am on a mooring can I take measurements with the transmission in reverse ?

          Also can you give better detail as to where the measurements are to be taken ?
          S/V Gosling
          Westport CT .

          “Believe me, my young friend, there is nothing - absolutely nothing - half so much worth doing- as simply messing about in boats.”
          ― Kenneth Grahame

          Comment

          • ndutton
            Afourian MVP
            • May 2009
            • 9601

            #6
            You won't apply as much load on the engine due to a lower gear ratio in reverse. Is it feasible to have someone skipper the boat around the harbor at 1700 RPM while you take measurements? Really, the only reason to duplicate the test parameters is to get an accurate comparison of the numbers.

            As for more detail of measurement locations, I think the headings in the provided table are pretty self explanatory. Which of them need more detail?
            Neil
            1977 Catalina 30
            San Pedro, California
            prior boats 1987 Westsail 32, 1970 Catalina 22
            Had my hands in a few others

            Comment

            • tenders
              Afourian MVP
              • May 2007
              • 1440

              #7
              Originally posted by joe_db View Post
              My engine is very similar. I have to run it at full power for some time in warm water to budge the temp past 120. When I was experimenting with FWC I could easily get 180-190 or more and the resulting heat in the boat was not pleasant on a hot day.
              I know all the theories of why this is not good, but practically the engine seems to be just fine, no sticky valves, and the oil gets hot.
              I'm with joe_db. Keep it cold. Even remove the thermostat and plug the bypass so the full flow of the pump goes through the entire engine - removes the need to understand ANY of the lengthy cooling considerations and descriptions in Don's most recent technical tip.


              So many more benefits to a cooler engine than the benefits of a "correct" hot engine.

              Comment

              • capnward
                Afourian MVP
                • Aug 2012
                • 335

                #8
                Although it is said that hotter engines have cleaner combustion, that is not a good enough reason to risk overheating. No doubt the trusty A4 can run cold indefinitely, although I suppose the plugs might foul eventually. There is no thermostat or bypass on my engine, all the water goes through the block to the manifold. I used to try to get a temperature of 180, because I read somewhere here that is best for FWC. So I used a thermostatic mixing valve sold by Indigo at the time, which worked ok for a few years until it melted internally from overheating, because I installed it wrong. Then I routed all the coolant through the HX all the time, but it would barely get to 125. So I installed a valve at the HX to restrict the flow into it. Then it would get too hot after shutdown and the alarm would go off if restarting. Alarm would go off once coolant was flowing. So I removed the valve, and installed an Indigo thermostat attached to the HX. Now I run about 160. No alarms as long as the HX is full of coolant.

                Comment

                • joe_db
                  Afourian MVP
                  • May 2009
                  • 4474

                  #9
                  Melted..

                  The Indigo thermostat is all metal! That must have been hot!
                  Joe Della Barba
                  Coquina
                  C&C 35 MK I
                  Maryland USA

                  Comment

                  • ndutton
                    Afourian MVP
                    • May 2009
                    • 9601

                    #10
                    I also ran for years with FWC, no thermostat and bypass fully blocked at 180°. I never gave it much thought until the new thermostat came along. It got me to thinking, my system was hanging on the ragged edge, the upper limit of temperature recommendation. It also occurred to me that under power I was fixated on the temp gauge because of it. That was no temperature control at all. I finally had to admit my ebay HX was barely keeping up.

                    I also had to admit I hadn't given my cooling system the same attention as the rest of the systems ancillary to the engine. My fuel system has a new second tank, new alcohol rated hoses, filter change annually, a polishing system, regular fill plate O ring replacement and no fuel dock gasoline. My engine electrical has been completely replaced paying careful attention to wire gauge, colors and terminations. Ignition, that's a saga right there. My exhaust hot section has been replaced as well as the stainless check valve at the high point down stream. I came to realize the cooling system deserved no less.

                    Testing MMI's new thermostat, the extensive temperature measurements disclosed weaknesses in my cooling system that I had ignored. Most importantly was the HX capacity. The original Sendure I bought on ebay was a 2 pass HX, I replaced it with a new SeaKamp 4 pass that was as big as available space would allow, the thought being with excess cooling capacity a thermostat could actually restore real automatic temperature control. And it did. Subsequent tests indicated leakage between the thermostat and the bypass port. I dressed the port in the old thermostat housing with a countersink without improvement so a new MMI thermostat housing was installed.

                    Now I run at 160° ~ 165°, electric FWC, completely under control and can actually converse with onboard guests instead of staring at the temperature gauge.

                    The point of all this is running without a thermostat is, once again IMO and I was guilty of it myself, a work around for other cooling system issues. It treats the symptom effectively but not the cause. Why wouldn't you give the cooling system the same attention, analysis and care as other engine systems?
                    Neil
                    1977 Catalina 30
                    San Pedro, California
                    prior boats 1987 Westsail 32, 1970 Catalina 22
                    Had my hands in a few others

                    Comment

                    • joe_db
                      Afourian MVP
                      • May 2009
                      • 4474

                      #11
                      In my case it is not lack of attention. The extra heat from the barely adequate FWC system caused vapor lock issues during long transits sometimes and heated up the boat too much always.
                      I think you are 100% correct, the stock heat exchanger most of us use is just not big enough when the engine is run hard in warm water. My Indigo thermostat "worked" great as in a fast warm up, but it was not regulating once the engine got hot. It was diverting all coolant to the HX and still the temps were going higher than the set point.
                      So right now I have RWC again and the temps are cool at any power setting. Long term plans are to go back to FWC with a bigger heat exchanger and possibly a mechanical pump or maybe a bigger electric pump. I want the FWC system to be able to hold temps to 120 if I want it to so I have the same cooling ability I have now.
                      I also have contemplated a fuel return to eliminate fuel temp issues and also make bleeding filters easy.
                      Joe Della Barba
                      Coquina
                      C&C 35 MK I
                      Maryland USA

                      Comment

                      • ndutton
                        Afourian MVP
                        • May 2009
                        • 9601

                        #12
                        Originally posted by joe_db View Post
                        Long term plans are to go back to FWC with a bigger heat exchanger and possibly a mechanical pump or maybe a bigger electric pump.
                        What electric pump were you using? I have two Johnson CM30P7-1 pumps in series and a Hellacious water heater loop to and from the V berth, it's working well.

                        I want the FWC system to be able to hold temps to 120 if I want it to so I have the same cooling ability I have now.
                        Completely doable with a big enough HX although if contemplating a thermostat it will be working against the 120° goal, more like 150° (MMI's lower temp stat).


                        I also have contemplated a fuel return to eliminate fuel temp issues and also make bleeding filters easy.
                        I love mine!
                        Neil
                        1977 Catalina 30
                        San Pedro, California
                        prior boats 1987 Westsail 32, 1970 Catalina 22
                        Had my hands in a few others

                        Comment

                        • joe_db
                          Afourian MVP
                          • May 2009
                          • 4474

                          #13
                          I might not run the engine at 120, but I want to be able to
                          Joe Della Barba
                          Coquina
                          C&C 35 MK I
                          Maryland USA

                          Comment

                          • capnward
                            Afourian MVP
                            • Aug 2012
                            • 335

                            #14
                            Just to clarify, I did not melt an Indigo thermostat. It was a Honeywell thermostatic mixing valve, like you see in household applications. It had a dial on the top to adjust the amount of mixing hot and cold. It has been many years, but I seem to recall buying it from Indigo. Maybe it didn't exactly melt, but it sure stopped working. While removing it, I did some research and found I had been feeding hot water into the wrong side. The high end of it's temperature range is 120 degrees. I'm surprised it lasted as long as it did. Anyway, I am happy with the Moyer HX and the Indigo thermostat, but the water is around 45 degrees here.

                            Comment

                            • ndutton
                              Afourian MVP
                              • May 2009
                              • 9601

                              #15
                              Originally posted by joe_db View Post
                              I might not run the engine at 120, but I want to be able to
                              Checking my records I found I did a test with the new HX, no thermostat, bypass closed (maximum cooling), raw water temp 62° - - - 125° @30 minutes from cold start, 1700 RPM in fwd gear.
                              Neil
                              1977 Catalina 30
                              San Pedro, California
                              prior boats 1987 Westsail 32, 1970 Catalina 22
                              Had my hands in a few others

                              Comment

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