Missing pushrods on FR730V

S

Striderashka

Member
Engine was running rough. Popped the valve covers on my FR730V. Right side was fine, minor valve clearance adjustment done on exhaust valve. On the left side the pushrods were missing! Tappets are fine, no holes in cylinder, rocker arms are fine, no evidence of a hole in the piston. I am stumped. Any ideas?
 
It is possible to drop a pushrod due to incorrect adjustment, and it could go down the windage hole and into the crankcase. I don't see how both pushrods would do this.
 
I agree. It is pretty obvious that they both went into the crankcase. Gap is always set at 0.12mm on TDC of compression stroke for each cylinder on a cold engine, and I check this twice a season. I keep spare gaskets on hand for this. Engine shroud is removed and engine blown out with air hose monthly so the is never any buildup of debris. Monthly checks done on plugs. Looks like I will have to break open the engine to remove the pushrods. What a drag.
 
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Depend on the age and usage of the engine valve guides maybe migrated causing the push rods to be bent. I just did a FX850 with 3000+ hrs where both exhaust valve guides have nearly migrated to this point of bending the push rods from carbon build on the valve stems.

I also had a couple Wright stand on ZTRs this year where the hydro cooling radiators were clogged and with them directly over the engine's cooling fan overheated the engine and valve guides
migrated.

Now the JD Z950R will need to have some electrical bypass surgery done on the VCU as the PTO output has failed. At least I have the wire and weather proof relay on hand. Now just to get my headache to go away. Customer will lose his emergency PTO stop function on the RH control arm; otherwise, all the safeties will remain intact.
 
Hmmm....that is an unusual dilemma. I've seen pushrods fall out of the rocker arm and even
down in the cam and lifter area before, but not swallow both push rods! You would think there
would be a banging like a mule kicking in a tin stall having done that. Trying to think of a way
to fish them out without disassembling.
 
DaveTN said:
Hmmm....that is an unusual dilemma. I've seen pushrods fall out of the rocker arm and even
down in the cam and lifter area before, but not swallow both push rods! You would think there
would be a banging like a mule kicking in a tin stall having done that. Trying to think of a way
to fish them out without disassembling.
Click to expand...
I've seen one wrap itself around the camshaft. Not likely getting it out without pulling the crankcase cover.
If the pushrods did go in. Borescope?
 
Borescope is a great idea to verify, but even with a magnet on the end, it would probably not be strong enough to pull out the pushrods. I don't see any other viable solution other than pulling the engine, and disassembling. BTW, there was no knocking, banging or any suspicious noise. The tip-off was a loss of power, suggesting opening the valve covers to take a look. Prior to that, all valve gap adjustments had been made to spec and the torques were to spec in in/lb. TDC on compression stroke verified with magnet location on each ignition coil and visual of pistons position. Everything has always been done precisely correct. None of this makes sense. Never heard of this before.
 
You are correct. You will not likely get the parts out with a magnet. I'm not even sure you would be able to see with a borescope, but it would be worth a try.
I highly doubt both pushrods would go into the crankcase. Please update when you find out.
 
I decided not to pull the engine and pull the crankcase cover off. The engine is 10 years old and has 1850 hours on it. (I edited this, I had typed 1350 instead of 1850). Time for a new engine anyway. I installed 2 new pushrods, adjusted the rockers, new plugs. It runs fine. So far. Of course, at anytime, if I hit a hard bump, the possibility of one of the free pushrods in the crankcase cover wrapping around the crankshaft or governor or whatever is a real possibility. So I go slow and avoid bumps if possible. Not a solution, but it is time for another engine.
 
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