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1965 coolant steaming

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  • 1965 coolant steaming

    In my 65 390 engine. When engine is hot
    And turned off there is a steam coming out of
    Overflow tube on surge tank.
    Is this normal or I need to add coolant.
    Appreciate any help.

  • #2
    That would be normal if the tank were overfilled. That is why it is called an expansion tank. Leave it a couple of inches shy of full when cold.

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    • #3
      Thanks.
      But there is room there for expansion.
      Could it be that there is no enough fluid there.
      It doesnt do it when engine is running and it's hot.
      Only starts about a minute after engine is turned off.
      Any ideas?

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      • #4
        Jack, do you enjoy working on engines? I ask this because you can do a simple procedure that will take up one Saturday afternoon, but the rewards are great and it doesn't cost much if you do the work yourself.

        Your engine is old. Has it ever been overhauled? I could ask a ton of questions but I will get to the point...

        It might be time to clean out your water jackets and change freeze plugs. You can do this in your driveway. Disconnect your battery, pull your starter, and remove all six freeze plugs. Then start your garden hose. Using a coat hanger and lots of water, go around the bottoms of your cylinders with the coat hanger and let the water flush the engine. Do both sides.

        Buy brass freeze plugs and tap them in with a small hammer. Replace your starter, antifreeze, and battery connection. Done.

        CLICK HERE to check out the nasty freeze plugs in the 390 I'm doing for Penelope.

        You may have a simple problem like a leaky radiator cap, but it is high time your block gets a proper flush. These kits sold by Prestone aren't capable of really cleaning your block. I often wondered why all the Squarebirds have an overheating problem. Then I found out why... any block doesn't stand a chance with so much mud inside, and most folks won't do freeze plugs until one leaks. - Dave
        My latest project:
        CLICK HERE to see my custom hydraulic roller 390 FE build.

        "We've got to pause and ask ourselves: How much clean air do we need?"
        --Lee Iacocca

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        • #5
          Thanks Dave
          I will certainly look into it before spring comes.

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          • #6
            Cleaning the block and replacing the core plugs are both worth while things to do, but as to the steaming it's pretty straight forward. The coolant level is to be at the baffle in the expansion tank, no higher. Steam coming from the overflow hose is either too much pressure building in the cooling system, or a bad cap. A pressure tester on the engine while running will show if it's building pressure, that's not a good sign and indicates bad head gaskets or cracks in the castings. If you're unsure of the cap at all, just replace it. The book calls for a 12-15 lb cap. You didn't mention if you had problems with overheating. Hope that helps, Bob C

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            • #7
              Thanks Bob
              It is not overheating but the temp gauge tends to occupy
              Letter "p"- is this too high?
              Can you tell me how to check pressure?and what it should be.
              I'm also thinking of checking radiator bottom for mud.

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              • #8
                Jack, my radiator shop will pressure test and flow test for free if I bring in a bare radiator. Typically, lime deposits plug your cores and prevent flow. Fresh antifreeze has mild phosphoric acid (like CLR) that keeps your cores clean.

                A hand-held infrared heat gun, pointed around your radiator, will tell the real story.

                Your engine is another story. Coolant flow can take many paths, and you know that flow always takes the path of least resistance. After corrosion sets in and rust builds, you may have engine areas that get no flow. Those areas remain wet but they create steam. Pressurized radiator caps raise the boiling point nearly three degrees per psi. - Dave
                My latest project:
                CLICK HERE to see my custom hydraulic roller 390 FE build.

                "We've got to pause and ask ourselves: How much clean air do we need?"
                --Lee Iacocca

                Comment


                • #9
                  Originally posted by Jackgo View Post
                  Thanks Bob
                  It is not overheating but the temp gauge tends to occupy
                  Letter "p"- is this too high?
                  Can you tell me how to check pressure?and what it should be.
                  I'm also thinking of checking radiator bottom for mud.
                  Your temp is a bit high, it should run right in the middle of the 'M'. You should verify the accuracy of the gauge first before 'fixing' anything With the car at operating temp, check the water in the top tank, it should be very close to the T'stat temp. If in doubt replace the electric temp sender just behind the distributor (get a good one). To see if your system is building pressure, a tester is used. I have a Stant brand http://www.stant.com/Consumer-Produc...rs---Adapters/ I don't recommend you buy your own, they're not cheap. The tester is put on the expansion tank and the car is run, if compression gasses are present, the gauge will show the pressure rise. Some increase is normal, but more than a few pounds usually indicates trouble. You aren't overheating or boiling over, I doubt you have a serious problem. As Dave offered, a radiator shop can make that test, and test the cap with the same tool as well as use the infrared to check temps. You can get an infrared fairly cheap if you catch one on sale. You probably need a good flush and a new cap, but have it looked at to be on the safe side. Good luck, Bob C

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                  • #10
                    Thanks Bob
                    Could all this be caused by a faulty thermostat?

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