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This is a 6 yr old mower with about 700 hrs on it. This is a 724 cc engine with cast iron cylinder sleeves. For the past 6 weeks, the power level had been slowly diminishing and last week it would not start. Checked for spark which was OK, checked for fuel and had that. There was compression on one cylinder, 90 psi and zero on the other. After a lot fooling around, pulled the valve cover and found a bent push rod. We straightened the push rod. Then freed up the stuck valve by gently taping the end of the valve with soft cushion and a soft hammer. Reassembled every thing and the engine fired right up.

I have ordered two aluminum push rods and two steel push rods. Not sure which one I will use to replace the old rod.

In my 75 years existence I have never heard of a small engine bending a push rod. I has seen several automobile engines bend rods but never a small engine. This is a heads up for everyone.

It is common on briggs engines to have the valve guides move in the heads if the air flow is restricted and causes the head to overheat. I have seen push rods bend on briggs Vanguards for no apparent reason, the same with kohlers.

lanceh5 said:

After a lot fooling around, pulled the valve cover and found a bent push rod. We straightened the push rod. Then freed up the stuck valve by gently taping the end of the valve with soft cushion and a soft hammer. Reassembled every thing and the engine fired right up.

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That is why it bent.

Luckily the piston didn't hit it.