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1996 Johnson 115 60 degree lower bearing failure

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  • 1996 Johnson 115 60 degree lower bearing failure

    Hey all,

    If you happened to catch a post I had a month or so, I purchased a boat that had a bad motor. I swapped the powerherad and finally got around to tearing down the seized one. First off i gotta say, "I love these motors". Entire teardown went faster than most other motors I have rebuilt and not one broken bolt. (sure beats my last Suzuki lol.)

    Unfortunately the motor had sat for a few months before I purchased it, so I didn't get a chance to see it freshly after it froze. As far as condition, the lower two cylinders/pistons were oil free and dry and rusty. The upper two were perfect, including a nice coat of oil. The upper rod bearing on one of the lowers (not at home- forget which one) had come apart and is the reason for the failure. The case was good except for one of the journals that had some scraping from a loose bearing. The crankshaft was dry on the lower two cylinders but had a heavy pool of lubrication at the lower bearing/main seal. Heavy scoring on one of the lower cylinders from a bearing and moderate on the other. The thermostats --one was tested o.k., the other was stuck mostly open.

    My question is this. From the above (will try to post photos later) is there a most likely cause? Overheat? lubrication (premix motor though) , lean seizure? Vacume leak (lean seisure)? Were the cylinders dry because they were on the exhaust stroke when it seized and not a result of it?

    I really like my now running (same model) motor, but potential issues with all the balance tubes and vacuum lines scare me. My running motor is premix with a traditional high volume pump feeding the original vro pump (minus the oil). Are there things you more experienced with this motor could recommend to simplify or improve on the intake side of the motor? Is there anything I should retrofit/replace that are known to fail. As easy as these are to tear apart, I would hate to have to loose a bunch of time and money doing it.


  • #2
    And why do you think cylinders ----" were dry because they were on the exhaust stroke when it seized "----Can you explain that question ?----Note---There is no " exhaust stroke " on a 2 stroke like there is on a 4 stroke motor.


    • #3
      O.K. So I meant the power stroke. Would be dry due to those ports being more open to the Florida humidity, as if the piston stopped in that position they wouldn't have the reeds and carb throttle/choke plates sealing them off. They would also have less lubrication if it stopped at this point in the revolution as more of the oil would have burned off in the power stroke.

      Have purchased many a PWC engine that sat seized simply from sitting that way. Motors of that type do have a box that traps water if it isn't properly blown out after use though.


      • #4
        Sorry-----There needs to be a review on how thing work here.


        • #5
          If a motor is not turning then the reeds will be CLOSED !-------And why the 2 fuel pumps as per post # 1 ??-----And do you really understand what happens to the oil once it goes through the carburetor ?-----As where does it go and how long might a particle of oil stay inside the motor ?
          Last edited by racerone; February 5th, 2019, 02:45 PM.


          • #6
            Yes, that is why I am saying that when the motor is stopped with the exhaust ports open, the EXHAUST side is exposed to the elements. If the other way around piston blocking the exhaust, the reeds and carb (all closed) protect the cylinder from the elements when it is not running.

            I wasn't hoping for this to be a debate on semantics though, as these have nothing to do with the original question.


            • #7
              Perhaps the motor sat slightly submerged for a while


              • #8
                In post #1 what lower bearing are you referring to.------Post some pictures of this mess.


                • #9
                  As far as the 2 fuel pumps, I just want to make sure my running motor is up to par. I suppose two fuel pumps were put on due to the fact that the fuel needs at WOT wouldn't be sufficient with one. It wasn't a modification I did, so was wondering if that is something that is O. K. or done with these.


                  • #10
                    I will post photos when I get home. Everything is in bags now. I tore it down last week but just recently got to thinking that it would be nice to know it there is anything that I should pay particular close attention to on these.

                    If it wasn't clear in my first post, I am talking about two different powerheads. One running fine that I would like to keep that way. And one that was seized when I purchased it as was trying guess what happened to it.

                    As far as partially submerged, good guess, it would back up the fact that the driveshaft was severely stuck to it., The outside portion had no signs of corrosion , but it could have been rinsed off.

                    My main concern here is what to do to give the running powerhead and long and healthy life. I will take photos of it (and the double pumps) in the morning as it will be dark when I get home.


                    • #11
                      So here is my running motor. The photo that shows the fuel pumps is how the previous owners mechanic set this up ( i know the main fuel line isn't connected). The aluminum bracket that holds the pulse line to the extra pump is all it does. The pump isn't supported with a bracket. If I keep this configuration, i will fabricate a bracket. My guess is it was either done this way to eliminate any possible fuel starvation at WOT, or he didn't have the adapter(connector) that would allow the traditional pump to connect to the vapor separator. Who Knows??

                      The second photo shows the wires to the trim motor. They are just individual female spade connectors connected to the males in this plug. Is that right?? Sure doesn't seem so? Weird thing was that the other motor was hooked up the same way. I wasn't quite sure by looking at parts diagram, but is this the part I need (0513664)

                      The third photo showing the balance tube looks like it was epoxied. What will a leaking balance tube cause? Should these be replaced with new on an old motor?



                      • #12
                        2 different motors with different issues/problems in one thread is gonna get very confusing very quickly


                        • #13
                          That's a cobbed together repair and it going to cause more problems...The air cover is missing and it is a restrictive design,unless the main jets was increase it will run lean at WOT
                          When in doubt,Trim it out!!!
                          Business Owner & Certifed Technician
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                          13ft Allison w/150 I-6
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                          14 x 48 Drifter with 1100SS Merc


                          • #14
                            Looks like the wrong pump installed, almost like the 2/3/v4 crossflow crank pulse hose driven fuel pumps.

                            If it is, that pump on there won't supply enough fuel output for that 60 degree motor.

                            I hope the VRO fuel pump mounting holes are still intact of that crappy hack job.

                            Mastertech marine has the best aftermarket designed pre-mix only pump kit for the money that should allow you to install the airbox back on for a 60 degree v4 using the VST system.

                            They also provide installation instructions.

                            You will need to do your own internet research to find them, as a link posted here may go against iBoats forum rules about parts links to competitors.
                            Last edited by havoc_squad; February 7th, 2019, 10:13 PM.


                            • #15
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                              Hey thanks for the responses, I had to run out of town, sorry for the delay. Sorry to switch gears on this thread, even though my goal was note any common lean seizures on this model due to the nature of the many possible vacuum leaks, I did get off topic. please just a little more on the VRO though.

                              I had the air cover off so I could get a better photo of the layout. It will be put back on before I run it. I haven't had this motor on the water yet, as I just changed the powerehead to this one and just remounted the motor on the boat. If you notice, the VRO pump is still there. This other pump is just feeding the VRO one. I guess I could just remove it, and test the output of the existing VRO as per the manual . Unfortunately I wouldn't be able to do the initial vacuum test as I would need a prop wheel for the full throttle initial part of the fuel system check. I guess I could just check for 3psi fuel pressure at idle, and not worry about air leaks for the moment. The mounting plate wasn't modified at all. Looks like they just used a pulse fitting to the new pump which supplies the existing VRO pump and just let it hang by the hoses. Unlike the mastertech system, the guy that did this ran this pump inline with the existing VRO. Is there a benefit to using the mastertech pump on a premix motor rather than a VRO only if the VRO still works?

                              Not sure if this helps at all (unrelated), but here are photos of the bad powerhead. Guesses on what its demise was? Again this motor used premix and a single VRO pump. Tank in boat (new to me) did have had oil in the gas & just assuming it was the correct ratio. I could be off in my cylinder numbers, but the bottom two are rusted, only severely damaged liner was bottom starboard. best way to tie this thing together--..any chance it was due to a lean condition. ( I forgot if the owner it failed on mentioned if it happened at idle or full throttle--sorry)