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    Advice please

    System not pressurising. I have had water pump leaks in the past. I pressure tested the overflow bottle to 20lbs with tyre pump. Holds pressure. I pressurised the rad and water leaked from the pump into the vee until the pressure dropped. When stopping after driving there is no visible water in the vee. Could this be because in this heat the water is evaporating so it isnt visible? Could the leaking water pump prevent the system from pressurising. The overflow bottle fills to about 3/4 but is not being sucked back into the rad on cooling. Car runs fine and cool. Any suggestions please.

    Many thanks. Mark

    #2
    Hi Mark

    I imagine the leak from the pump is stopping the pressurisation happening - it needs to be completely sealed to pressurise properly. This will also probably explain the lack of syphoning back into the overflow. You're right about the heat evaporating the water in the V, have had the same. Get the carbs and manifold off and hopefully the pump will come out easy enough for you to fix.

    Good luck!
    77 Mk2 TV8 in Brooklands Green

    Comment


      #3
      Originally posted by kevin p View Post
      Hi Mark

      I imagine the leak from the pump is stopping the pressurisation happening - it needs to be completely sealed to pressurise properly. This will also probably explain the lack of syphoning back into the overflow. You're right about the heat evaporating the water in the V, have had the same. Get the carbs and manifold off and hopefully the pump will come out easy enough for you to fix.

      Good luck!
      Thank you kevin for your prompt reply. I was starting to get worried lol. Strange because the car runs on 1/4 even in this heat! Doesnt seem to to lose much coolant. If I left the coolant in the overflow at 3/4 and drove the car tomorrow, would the existing coolant in the rad expand further and then fill the overflow bottle resulting in coolant loss? ps too cowardly to take the manifold off. Many thanks Mark

      Comment


        #4
        Mark, I'm in the middle of curing a water leak caused by the water pump seals failing - if you need any help or advice I'm happy to help.

        Comment


          #5
          Hi Mark

          I think there is a difference between coolant loss and over heating. The latter only follows the former if nothing is done about it - and it can be quite quick. So, it's good that the temp is running ok, and you need to either fix the coolant loss issue by repairing (or having repaired) the pump. The result of a leak is also air in the system, so you may find that the 3/4 in the overflow will drop back if you can purge the air. Trouble is you need to keep doing this until you fix the leak! One thing I noticed was the leak only occurred when running from cold - as it warmed up, I assumed all the components expanded and seemed to seal themselves, until left to go cold again. The pump (and manifolds) can be tricky to remove / replace but if your methodical it's doable. Let us know how it goes.
          77 Mk2 TV8 in Brooklands Green

          Comment


            #6
            Originally posted by Robmsharp View Post
            Mark, I'm in the middle of curing a water leak caused by the water pump seals failing - if you need any help or advice I'm happy to help.
            Hi Rob, Thanks for the reply. I would be really grateful if you could pm me with any photos that you could take of overhauling the water pump as I have read on the forum that it is considered better to repair existing pump than to buy new. My concern is putting all back together, manifold bolts stripping thread etc. As we are in the summer I dont really want the car up on blocks if poss. Maybe I could persevere until winter? Its weird because this all started after I changed the antifreeze. Never had any problems in the past. I used 40% antifreeze, could this have contributed to an increase in pressure causing the pump seals to leak? Many thanks Mark

            Comment


              #7
              Originally posted by kevin p View Post
              Hi Mark

              I think there is a difference between coolant loss and over heating. The latter only follows the former if nothing is done about it - and it can be quite quick. So, it's good that the temp is running ok, and you need to either fix the coolant loss issue by repairing (or having repaired) the pump. The result of a leak is also air in the system, so you may find that the 3/4 in the overflow will drop back if you can purge the air. Trouble is you need to keep doing this until you fix the leak! One thing I noticed was the leak only occurred when running from cold - as it warmed up, I assumed all the components expanded and seemed to seal themselves, until left to go cold again. The pump (and manifolds) can be tricky to remove / replace but if your methodical it's doable. Let us know how it goes.
              Thanks again Kevin for sound advice. Will keep you posted. Cheers Mark

              Comment


                #8
                Chuck some K-Seal in it. Can't do any harm and may well keep you going until it is more convenient to tackle the problem properly.
                Dave
                1974 Mk2, Carmine, ZF 4HP22 Auto, 3.45 Diff, Datsun Driveshafts.

                Comment


                  #9
                  Originally posted by DJT View Post
                  Chuck some K-Seal in it. Can't do any harm and may well keep you going until it is more convenient to tackle the problem properly.
                  Hi, I have done that already. Do you think it safe to try again? Cheers Mark

                  Comment


                    #10
                    Have you run it up to temp and for long enough, I didn't and it didn't work, I ran it longer and it worked.
                    I only do what the voices in my wife’s head tell me to do!

                    Comment


                      #11
                      Originally posted by Jeff View Post
                      Have you run it up to temp and for long enough, I didn't and it didn't work, I ran it longer and it worked.
                      Hi Jeff, I did a 50 mile run the first time after adding k-seal and it seemed to work. I did the 50 mile run back and it started to leak again. Not sure k-seal will work on the pump? Going to fit a header tank to buy me some time. At least this way I can still use it. Cheers Mark

                      Comment


                        #12
                        Misconception regarding header tanks.

                        They do not assist with cooling, just give a better method of checking level and a bit of safety if level drops if a light and/or buzzer fitted.
                        I only do what the voices in my wife’s head tell me to do!

                        Comment


                          #13
                          Originally posted by Jeff View Post
                          Misconception regarding header tanks.

                          They do not assist with cooling, just give a better method of checking level and a bit of safety if level drops if a light and/or buzzer fitted.
                          Thanks Jeff, until I can get the water pump replaced, it will give me piece of mind know the cooling system will be full.

                          I have a question. Assuming the cooling system is original, using the overflow bottle, 100% air type, no leaks and works perfectly and water is returned to the radiator from the overflow bottle. Lets then assume from cold the engine reaches operating temp and the coolant expands, and 1/2 ltr overflows into the overflow bottle. Lets say for ease, there is 10ltr of coolant in the engine. After expansion there is now 9 1/2 ltrs in the system. Will this reduction in the amount of coolant now in the system comprise cooling? If a header tank was fitted, would that ensure that there is always 10ltrs in the system as, being gravity fed, it would replace the 1/2 ltr lost on expansion? Thanks again Mark

                          Comment


                            #14
                            Hi Mark, in theory when the water expands, you have 10 1/2 titres and the system will always have water in it. It should then cool down, shrink in so many words and revert to 10 litres but the engine sucking back from the expansion bottle what it expelled and so to you go back to the balanced starting point. Hope that makes sense.
                            Yellow Rules OK

                            Comment


                              #15
                              Originally posted by Andrew S View Post
                              Hi Mark, in theory when the water expands, you have 10 1/2 titres and the system will always have water in it. It should then cool down, shrink in so many words and revert to 10 litres but the engine sucking back from the expansion bottle what it expelled and so to you go back to the balanced starting point. Hope that makes sense.
                              Hi Andrew, thanks for that. Make perfect sense. what was i thinking! DOH! lol

                              Comment

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