Hi gents, whilst trying to start my engine yesterday the pull cord became so tight it would not rotate the flywheel. So after inspection I cant see anything obvious that may cause this so I pull the engine apart to have a look- pulled out the crankshaft, piston, rings, cogs etc. All looks ok, no crap, muck or foreign bodies etc. So I test to see that the workings are ok & flywheel spins by hand quite smooth & free with considerable compression, valves/ springs ok. I assume all ok at this stage. I commence to put it back together & all goes where (I think) it should. Again all appears ok. Top up with new oil & after I fit the crank-case cover attempt to turn the fly-wheel and it is tight as- cannot turn by hand at all. So I pull apart again, check etc etc, all appears ok (scratching my head at this stage)& three attempts later I find that when I tighten the crank-case cover this is what appears to be causing the stiffness. Loosen the nuts & this frees up the movement, tighten again & becomes stiff. I have attached a couple of pics to illustrate how I have placed the components back together. Obviously I am doing something wrong here..Any ideas or suggestions is appreciated as this has been a frustrating excercise thus far. Thanks - Ross
Someone else may chip in and and go straight to a solution, but I can only offer my standard approach to this: isolate the system that has the problem. That means remove one of the timing gears and reassemble the engine. Does it rotate freely then, with the camshaft not rotating? If not, forget the entire camshaft system and concentrate on the crankshaft. If it is the crankshaft, remove the connecting rod and piston and try again. At that point you are only trying to rotate the bare crankshaft. If it won't rotate, it is an endways clearance problem, and there are not many places it can be rubbing against.
Because this happened when the engine was running, it does not seem to be an assembly problem. Something has come apart, on whichever component it is that is the source of the problem. It should be simple once you have identified that component as above. To quote Sherlock Holmes, "when you have eliminated the impossible, whatever remains, however improbable, must be the truth".
Thanks Grumpy, pulled it apart again & lined up the timing marks- this was the issue. Reassembled & now ok. Strange though as the stiffness just "happened" the first time prior to me pulling it apart. I have no idea what would have caused this however.
Most likely it will happen again, Ross, since nothing has been done to fix it. It isn't anything to be apprehensive about - it isn't a very complicated engine, and the parts are available on the nearest nature strip.
Thanks grumpy, any ideas what may have cuased this?? I am not real keen on removing the engine from my cylinder mower & pulling it apart to fix every time it happens.
I don't recall hearing of the same problem on a B&S engine before, Ross. If I just go by what you posted, the problem appeared when you clamped on the crankcase cover, so most likely something was being squeezed axially. Without knowing whether it was part of the camshaft system or part of the crankshaft system, that is about as far as I can get - but since it appeared without provocation and suddenly disappeared when you dismantled and reassembled the engine, it may be that something has excessive slack axially, allowing something else to fall into the gap at times and jam everything. When you took the cover off, there was no axial constraint so it was free. When you put the cover back on with the wrong bit still in the gap, it jammed again. When you juggled everything around a bit, whatever it was fell out of the gap - for now.
