COMMENTS ON BENT PUSH RODS

[bob mitchell]

     As I mentioned in last post that I got my engine started but had a loud slapping click due to a bent push rod.   I found a few explanations for bent push rods on the internet. The first seems very reasonable for my situation - the valves get stuck on engines that have set up for a while - mine was not cranked for two condensation filled winter seasons, so it sounds reasonable. If a valve is stuck the push rod is bent when the engine is cranked. I replaced the push rod, which was the worst offender, but still hear another push rod, but it is not making as much noise. By seeing which rod it is, and seeing if it is a rod that would also correspond to a valve that had been shut (since valves shut and open in patterns, and I already know one valve that was shut (ie got stuck, assuming that they have to be making "shut" contact to get stuck - which may not be the case if it was the valve stem instead of the valve head that stuck) -------I should be able to figure out the other valves that might be in a position  to get stuck at the same time as the one I already replaced. That would confirm that the engine just set up to long. Supporting that theory is the fact that I never recall hearing the noise before.

         On the other  hand, the camshaft timing gear can shear a key and spin on the shaft, throwing the timing off. That means a valve and a piston may kiss, which could and probably would lead to a bent push rod. Any time you jump (lose) timing you have the potential to bend push rods, even with a backfire, which unfortunately when I bought the boat, was definitely happening. The engine did not originally run until I retimed it.  And I have timed it a few times since then. Anyway, I really hope that I don't have this problem, but will know in the next of weeks.

    A third explanation has to do with "carbonizing" where the engine is not run loaded enough to heat up to proper operating temperature and carbon forms on the valve stems, and the valves get stuck leading to bent push rods.

        The picture shown of tappet adjustment (valve clearence which must be done every so often, but definitely after replacing a push rod) is actually out of the Ford manuel that came with my engine (.014-.016 inch clearence @ operating temp.) Once again, I warn you, that I may not know what I am doing.