I've been working with a friend of mine who is a newbie to the hobby and for the last few sessions, I was showing him routine maintenance on diesels. Taking them apart, motor tuneups, lube, rewire etc. Last night we were going to start on steamers and I chose one of my 736s to work on as it's chassis removal is much simpler than some of the other smaller engines. When we finished with the clean and lube, we put it up on my rollers to test it out. It ran smoothly, but I was hearing kind of a "popping' sound. Put it on the track and again, it ran smoothly, but the popping was less obvious, so I attributed to smoke cam/piston noise. When we put the shell back on and ran it, we were getting short circuits. I identified the issue as the insulation on the smoke element wire pulling back (we had cleaned the smoke unit) and shorting the wire against the smoke unit cap. We ended the session at that point and my plan was to fix the short today and be done with it.
Well, it didn't work out that way. I fixed the short, but that "popping" sound turned out the be a bind in the rods which got much worse today to the point where it stopped....stuck. I took all the rods off to try to trouble shoot the source. Without rods, it ran smooth and quiet.....so it wasn't a worm/axle gear bind.When I put the main side rods on both sides (without connecting all the others (including the eccentric screw), it bound. Took one side off so it would run with just one main side rod (connected by the 3 hex screws), and it bound. Therefore, I ruled out quartering because the eccentric crank was not connected on either side, I'm kind of at a loss now as to the cause. Could both of those side rods be worn (at the hex screw holes)? They look fine.
Any ideas?
-Roger