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    Overheating-gctid406079

    Hello Guys,

    I've been having an over heating issue with one of my hino 135 - I have determined that it is probably a thermostat issue - has anybody had issues with the thermostat failing and if so, how difficult is it to change the thermostat?

    Any thoughts? Ideas?

    Regards,

    Sea Shift

    #2
    Are you getting a good water flow out the exhaust? If it's only one engine, check the water flow between the one that is and is not overheating to see if they are pumping equally. If flow is bad, start at the intake hose and thru hull and strainer for blockage, Then pull the exhaust hose and look for blockage if you have iron risers. Then go to the impeller, if still no problem go to the upstream side of the tube bundle for debris like pieces of busted impeller. What is the ambient water temp? In FL it's 90 so cooling is a little more sensitive, PNW is cold water, much more can be marginal before you overheat.

    If water flow is OK, it's either heat exchanger or thermostat. Thermostats are cheap so replace that and see if it helps. Also, is it actually hotter or is the gauge just showing hot. Gauges are not always accurate. I don't know those engines specifically but overheating is overheating. Start with simple and cheap and work you way up. If flow is OK, you probably have to get your bundles cleaned out, they aren't exchanging heat.

    Comment


      #3
      Thanks for replying.All parts of the system are good.I am trying to get info on the actual changing of thermostat on the Hino 150. How much of the cooling system has to be removed.Access to it is tight.Any thoughts or ideas would be appreciated.

      Regards , Sea Seashift

      Comment


        #4
        What exactly have you done to think it is a thermostat issue? In terms of overheating, this is not a very common problem on this engine. There's alot of hino owners here to assist you, so let's hear it.

        Ken

        Pugetsoundog (woof)

        Comment


          #5
          The thermostat is easy to get to. It's on top of the engine. Just follow the fresh water hose that goes into the ManiCooler you will see the housing for the thermostat. I believe 2 bolts hold the cover on. I have not had it apart but it is sealed by an O-ring. See parts diagram that shows it here, page 30 I think.

          http://www.bayliner32xx.com/uploads/...0Partsbook.pdf
          1997 3788/Cummins 6BTA 5.9 M2s (Sold)
          2003 Silverton 42c/Cummins 480CEs
          2019 Cobia 240 CC
          2006 Boston Whaler 13 Sport
          1985 3270/Hino 135s (Sold)

          Vero Beach, Fl.

          Comment


            #6
            After removing thermostat put it in a pan of water with a thermometer & place the pan on a stove. Note at what temp it starts to open & what temp it is fully open. Normaly these do not cause any problems. Good Luck
            Capt. Ron.
            "I will not tiptoe through life to arrive safely at death"
            "Never Trade Luck For Skill"
            1987 3870 - Northern Lights ll
            Hino EH700
            Westerbeke 8.0
            1999 Logic Marine 17' CC/50 Merc.
            on Louisiana pool Mississippi River.

            Comment


              #7
              Thanks for the replies.I determined that the thermostat was the issue because twice on the starboard motor the temp gauge climbed to 200 degrees and spat out about 4 litres of coolant. I then checked water flow , strainer ,impellor and found nothing amiss.So i then replaced the coolant and ran the motor again without any overheating.Have just returned home after a 3 week trip and am going to go at the thermostat and replace it. I can't think of any other reason for the overheat.Was wondering if any parts of the cooling system have to be removed to get at the thermostat..it doesn't look like it to me.Any thoughts?

              Happy cruising , Sea Shift

              Comment


                #8
                I have a 1988 with 135 hinos. We had similar problems and so did the previous owner, including having a shop look at it. They finally elected to just not push it hard. I strongly considered the t'stat, too, but still knew other things could cause the problem, including plugged tubes in the heat exchanger or plugged riser on the exhaust. A temp gun ruled out the plugged riser. I decided to look at the inlet side of the heat exchanger. Choice is to either pull the end hose or remove the end cap. I pulled the hose and on inspection found about 1/3 of the tubes were blocked with impellor pieces. To get them out required pulling the end cap, which is actually the easier thing to do. I cleaned out all the pieces out and confirmed all the tubes were clear by sliding a 1/8" rod down the tubes. Re-assembled and that was the end of the heating problem. Not long after that, we decided to rebuild the raw water pumps, which is not a hard thing to do. On removing and disassembling that pump, I actaully found a piece of the impellor wedged in the inlet side of the pump... go figure! Some thing else to consider. The heat risers on these engines are aluminum. They are subject to pitting without regular proper maintenance of your coolant. If they do eat through, you can ruin an engine. Our of my friends had this happen to his 175 hino and it was a +10K repair! For me, that would have been a killer! The only real way to check this is to pull the exchangers, which is a much bigger job, but doable. We found ours were not pitted, but went ahead and had them ceramic coated while we had them out. This is a dip type process that puts a ceramic coating on the insides of the passages. As to changing the thermostat, it does not look like a difficult job, but yes, it is in an awkward place. Good luck in howver you proceed and let us know what you find.

                Ken Rose

                Pugetsoundog (woof)

                Comment


                  #9
                  Thanks Ken, I will let you know what i find.The rubber impellors seem to be a bit of an issue with these.I check mine on a regular basis and haven't had a problem but a better pump system would be optimum.

                  Regards , Sea Shift

                  Comment


                    #10
                    Some other comments.The end caps are sealed with a large o-ring. The outside surface mates against the exchanger and cap. The inside surface holds the tube bundle. This o-ring also separates the raw water from the coolant. I found when I pulled the caps, the o-ring stayed in place and that kept the bundle seated correctly. I'd suggest still draining down your coolant, though. Also I rebuilt the raw water pumps because I did not know their history.It comes off simply by disconnecting the in and out hose close the thru-hulls), and a couple of bolts. The pump body is round on the inside where the impellor turns. To make it function, there is a bronze cam that mounts on the inside. It is secured with a single bronze screw, very small, like 10-32 size (yeah, I know, probably metric, but that's about the size it looks like). If it comes out or corrodes away, the cam peice spins destroying the pump. So I pulled them out on the off season and went completely through them. Not that hard and now I know exactly what I have. If you wanted, you could also replace just that little screw from the outside, but I'd at least pull the impellor out to confirm the screw went correctly into the cam piece.

                    Ken

                    Pugetsoundog (woof)

                    Comment


                      #11
                      I was having overheating problems also on my starboard side engine. The impeller was tore up and after taking the heat exchanger apart twice and replacing impeller twice I took advice from the post and looked at the intake side of fresh water pump found all the missing pieces to impeller lodged in the hose. Cleanded them out and engine runs cool as a cucumber. Thanks for advice!

                      Comment


                        #12
                        Hello Fellas,

                        An update on the overheating issue. I removed the thermostat , not too hard of a job,1 1/2hrs. I left it out and re-assembled everything.Took the boat out for a trial and naturally the motor ran a lot cooler in comparison to the other one.Running at 2100 RPM the temp is 170. After bumping up to 2600 the temp climbs to 185. So knowing that i have good water intake, good impellor, clean bundles, i have to think there is a small blockage somewhere in the mani-cooler as it only heats up at the higher RPM.It looks like i will have to take the thing apart and go from there.

                        Sea Shift

                        Comment


                          #13
                          "i decided to look at the inlet side of the heat exchanger. Choice is to either pull the end hose or remove the end cap. I pulled the hose and on inspection found about 1/3 of the tubes were blocked with impellor pieces. To get them out required pulling the end cap, which is actually the easier thing to do"

                          Another way to remove the impellor pieces is to remove the hose on the end of heat exchanger cap and use a shop vac. I have a small 1 gallon wet/ dry vac. Put the vac hose over the end cap and the vac will pull the water and impeller pieces into the vac. When you dump the water out look for impeller pieces. You need do this about three times. The vac will pull all the raw water through the heat exchanger and any impeller pieces. Should keep a small 1 gallon shop vac on board incase you impeller goes bad you have a easy way to clean out the exploded impeller. When you remove old impeller and there are pieces missing you know were they are and how to retrieve them.
                          1987 3270MY, 135 Hino engines

                          2015 Element ( Lime Green) Limited Edition 75 HP Mercury.

                          Roger, Lake Saint Clair, Michigan
                          Fair Winds & Following Seas

                          Comment


                            #14
                            The thermostats are very robust and likely not the issue.

                            On my 3288, I was having increasing temps on the starboard engine, but not overheating.

                            I had the bundles pulled and cleaned and the issue was resolved.

                            Over a number of years, there will be buildup on the bundles, preventing the required heat transfer

                            They need to be cleaned at periodic intervals

                            If you haven't had them cleaned recently, probably a good time to do it.
                            Pat
                            Paragon
                            1999 4788

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