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    Boiling sound from the front of the engine

    Hey guys,

    Yesterday I finally got my 77 750 in rideable condition to take her on a spin around the parking lot, also to practice for the skills test.

    A friend and I rode around a few times but one particular time I stopped and turned off the engine, the engine was quite hot and it sounded like something was boiling towards the front of the engine. After about a minute the noise stopped. We rode it around again and no sound, though I don't think it got that hot again.

    I searched and found this thread: Sounds like my oil is boiling but no conclusion was reached and it wasn't particularly hot out yesterday.

    Is this a normal noise? Or should I be looking for the problem?

    Thanks,
    Patches

    #2
    Seems to me that if the oil was hot enough to actually boil, you would have blown the engine and seized it up. The sound was most likely the exhaust flexing and cooling.
    MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
    1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

    NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


    I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

    Comment


      #3
      Entrapped moisture/h20 in old oil,voporizing out,or was oil new/fresh,oil was at proper level or not,old/new (correct)oil filter,Normal heating expansion sounds very noticable at low speeds,I have no answer ,only maybes.Tell more if happens again.

      Comment


        #4
        Did a bit of checking...seems the average boiling point of 10 W 40 is approximately 500 degrees F. At that temp you would have most likely melted a pisiton or something else..I like the trapped moisture theory. If your doing short parking lot trips, it makes sense. The engine heat and cooling cycles makes internal condensation..at very little amounts. This usuallly evaoprates on a longer sustained riding situation and never is noticed. However, the short parking lot practice runs doesnt get the oil hot enough for long enough, so therefore each time you do the practices you are actually adding a bit more condensation rather than cooking it out of the oil.
        MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
        1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

        NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


        I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

        Comment


          #5
          Yes.H20 if in oil start off/gassing/vaporize sooner, even before it's own boiling point,212-214 deg.f or so. Chuck right on w/recalls/research.Thanks

          Comment


            #6
            I heard the same thing right after I had done my first valve job and replaced the gasket there. When I ran it again after that I have heard nothing since.

            Elrico's theory kind of makes sense in this case seeing as how I had my valve covers off for over a week waiting on shims and gaskets. They were covered, but humidity was high during that week so I suppose some moisture was bound to settle in there. Initially I thought maybe it was oil cooking into the new gasket or something. Hell, idk.

            Comment


              #7
              Worst thing you can cover an open engine with is a plastic bag..unless its outsdie and rain is possible. Plastic acts like a terrarium and traps any humidity and wont let it escape. I prefer a cloth cover that can breathe if its inside. This will keep dust and crap from falling in yet allow moisture to pass thru it.
              MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
              1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

              NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


              I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

              Comment


                #8
                Water under the cam cover boiling off. The early DOHC Hondas are especially prone to this if you only fire them up for a short period before switching off. Nothing to worry about.
                79 GS1000S
                79 GS1000S (another one)
                80 GSX750
                80 GS550
                80 CB650 cafe racer
                75 PC50 - the one with OHV and pedals...
                75 TS100 - being ridden (suicidally) by my father

                Comment


                  #9
                  Great, thanks everyone!

                  I have been starting it up for short periods while changing the oil, dealing with electrical glitches and so on so moisture build up makes sense.

                  I won't worry about it.

                  Comment


                    #10
                    Get all the issues sorted and then a good 30 mile ride will dry it out pretty well.
                    MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                    1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                    NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                    I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                    Comment


                      #11
                      Originally posted by chuck hahn View Post
                      Worst thing you can cover an open engine with is a plastic bag..unless its outsdie and rain is possible. Plastic acts like a terrarium and traps any humidity and wont let it escape. I prefer a cloth cover that can breathe if its inside. This will keep dust and crap from falling in yet allow moisture to pass thru it.
                      Good to know. I feel better now since I had mine covered with shop clothes.

                      Comment


                        #12
                        Hijack: my commute to school is 10-15 miles each way, and I usually burn a tank of gas with weekend riding. Is the short schoolweek commut going to cause problems over the long term?

                        Comment


                          #13
                          Probably not 10 to 15 miles is a lot more than a few trips around the parking lot and idling in the garage. And a tank a weekend is probably around 135 to 150 miles..no worries if it was mine.
                          MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                          1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                          NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                          I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                          Comment


                            #14
                            Thanks chuck! Just wanted to be sure, with the allegedly subpar oiling scheme on the 16v 750, I don't need any more factors working against me.

                            Comment

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