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Broken valve springs, bent and broke push rods?-gctid396065

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    Broken valve springs, bent and broke push rods?-gctid396065

    working on a 85 merc 170 engine, had 0 compression in one cylinder, had already found 1 broken push rod with just the valve cover off then I pulled the head, cylinders look great, noticed 2 valves that were able to be moved in and out by hand aprox 1/16 of an inch, the others are tight, they are in the center 2 cylinders one is an exhaust the other that was in the cylinder with no compression was an intake. pulled the valves and both springs were broken in several spots, these were the valves that had broken and bent push rods the valves themselves seem to be ok and are reuseable. what could cause this? hydro lock, noticed the flapper was missing? what else/

    also what else should I look for, I pulled each lifter and compressed them to get all the oil out and it seemed milky, got them soaking in oil right now to refill. I noticed the 2 that were on the push rods that broke were harder to compress but once I did it they moved freely like the rest, they seemed to have the milkiest looking oil in them so I think it was water that wouldnt allow them to compress. going to pull the oil pan since I ordered a gasket set and it comes with a oil pan gasket. any other advice. the engine actually ran the way it was just not well and it didnt make any noises that I could tell. I dont want to spend a fortune on this boat, it is just a boat I got to tow behind my camper because I us a 4' extended hitch so my towing capacity is reduced

    #2
    It sounds like you may have had some engine "run on", and, or, backfire. With the flapper missing when a marine engine backfires, they make tremendous water pumps. Unfortunately they draw the water into the engine, not pump it out. That's probably where your milky oil came from. It's also likely that the water coming in caused some hydro locking which destroyed the 2 lifters.

    I'd drain the oil as asoon as possible to get any water out of your oil pan. I don't believe that you'll be able to change your pan gasket without pulling the engine.
    Bob Hawes.
    Kelowna, B.C.
    1998 Trophy 2052 WA
    4.3 Vortec, A1 G2

    Comment


      #3
      1-This engine overheat ? Head gasket went water got in MAYBE ?

      2-Head went, water got in MAYBE ?

      3-Freeze damage, water got in ? Cracked block MAYBE? Crack into the cylinder from the water jacket MAYBE ?

      4-Heat exchanger on this engine ! Was that checked ? Froze MAYBE ?

      5-Riser went ? Water usually goes into the back cylinders first, but it will be sucked into the open valves could be the middle ones MAYBE ?

      There are more let someone else chime in.
      Be good, be happy, for tomorrow is promised to no man !

      1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

      '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

      Manalapan N.J

      Comment


        #4
        Question... did you place the cam followers in a fixture so that they are in the same order in which removed?

        Pre-Run Flat Tappet cam followers must go back into the exact some bore and on the same cam.

        As far as I know, the Merc 170 cylinder head is a 385 series Ford... I.E., 460 Ford.

        Most any automotive machine shop will be able to repair or replace the cylinder if need be.

        Look closely in and behind the front cover area. This area provides the separation between the engine circulating pump, and the camshaft drive and shares a common seal surface area on the actual camshaft.

        Engine oil side.... vs .... Ethylene Glycol side.

        This area can be problematic.

        .
        Rick E. Gresham, Oregon
        2850 Bounty Sedan Flybridge model
        Twin 280 HP 5.7's w/ Closed Cooling
        Volvo Penta DuoProp Drives
        Kohler 4 CZ Gen Set

        Comment


          #5
          not a leaking manifold or anything, there isnt any rust in the cylinders or on the pistons, I think it was either they stopped suddenly and took on water thru the exhaust with no baffles, maybe it over heated and suddenly stopped or backfired like you guys said, either way my theory is the cylinders suddenly filled with water these two valves were the ones open or opening on the intake and exhaust stroke the piston compressed and Bam. now if I only knew thats what happened. the oil had to be changed several times because it was only slightly milky and the more I think about it it may not even be milky from water it could be milky from a running with the valves open and exhaust getting in the oil

          Comment


            #6
            no I didnt put them in order I was thinking about replacing them, but now I know they are ok maybe not. is it a huge problem? I am putting new pushrods in but had decided to keep the lifters/followers. would it be better to just replace

            Comment


              #7
              bbruno wrote:
              no I didnt put them in order I was thinking about replacing them, but now I know they are ok maybe not. is it a huge problem? I am putting new pushrods in but had decided to keep the lifters/followers. would it be better to just replace
              Man... I don't know what to tell you on that one!

              Logic suggests that the geometry between each cam follower, bore and cam would be identical.

              However, all warnings suggest DO NOT place pre-run followers against different cams.

              A brand new flat tappet cam follower has a mild convex profile to it's cam surface.

              .
              Rick E. Gresham, Oregon
              2850 Bounty Sedan Flybridge model
              Twin 280 HP 5.7's w/ Closed Cooling
              Volvo Penta DuoProp Drives
              Kohler 4 CZ Gen Set

              Comment


                #8
                and go thru a light break in period like with a new engine

                Comment


                  #9
                  how much can a hone actually take out of a cylinder, thinking about pulling the piston and honing the cylinder, its only a slight groove barely noticable by hand but its there, its in the cylinder that had a broken spring but ok compression

                  Comment


                    #10
                    I successfully married 2 470s about 9 years ago. This involved taking the best parts out of 2 engines. Notably the cam out of one and lifters out of both. Thoroughly mixed up the lifters and at last report IT was still running fine.1000 hrs or so later. Im a skeptic on the dont mix lifter thing.(Would really like someone to explain why it is so important)

                    Comment


                      #11
                      even though they are out of order, soaked them in oil put them in and just put the head back on and torqued it down, got my new valve springs in, lapped the valves, had to torque the heads to 140 foot lbs which was hell to do with a fractured index finger. had to order new push rods, napa ordered the wrong size even though I gave them the melling number so had to go to another store and will have them tomorrow. I also honed 1 cylinder that had a small groove from what looked like water flow??????? from the head gasket, that was a cylinder that had good compression cold, the groove only went down 1.5 inches so the rings were ok.

                      Comment


                        #12
                        FYI and FWIW: I'd take the scratch over a piston that is loose within it's bore.

                        If you did not remove much material from the one cylinder bore, you may be OK.
                        Rick E. Gresham, Oregon
                        2850 Bounty Sedan Flybridge model
                        Twin 280 HP 5.7's w/ Closed Cooling
                        Volvo Penta DuoProp Drives
                        Kohler 4 CZ Gen Set

                        Comment


                          #13
                          definately not from the piston, didnt take much out or the cylinder, hopefully I will have it back in the boat this weekend, while I have the engine out I pulled the transom assembly to reseal and replace the bellows, I mainly pulled it to replace the steering shaft seal, its a pain to do in the boat,

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