Unable to answer if valve opened or not but does sound like ur bottom valve is bent or piston made contact and bent it to fix need to remove head and replace valve also need to inspect piston face is not damaged from possible contact
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When an engine becomes too hot, the metal components, including the pushrods, expand due to thermal expansion. If the engine exceeds its designed operating temperature, the pushrod may bend as it struggles to accommodate the increased length caused by expansion. Another factor to look for is valve adjustment.
Most of the time pushrods are bent when the engine is over-revel and the valve hits the piston. Usually this is caused by a bad or mis-adjusted rocker or lifter be it ever so slight.
The bottom end of a pushrod is fitted with a lifter, upon which the camshaft makes contact. The camshaft lobe moves the lifter upwards, which moves the pushrod.
Bent valves will not only damage pistons but also valve guides, camshafts and valve train components. include bent valves, broken pistons and damaged engine heads.
The cause of the bent push rod is the valve guide thimble is only press fitted, and easily loosens when the engine reaches a certain temp. The thimble then pushes outward, restricting the movement of the valve spring, eventually causing the push rod to bend.
A sure indication that the pushrod is too long is when it takes more than 1 full turn to seat the rocker past the zero-lash point. Though we have successfully run pushrods with more than 1.5 turns, more than 2 turns can actually hold the valve open once the lifter is pumped up with sufficient oil pressure.
The servo shaft rotates clockwise, and the servo arm rotates along with it. The pushrod translates (moves) to the right and slightly down as it is pushed by the servo arm.
The force the pushrod exerts is the product of the amount of air pressure applied in psi, and the area of the diaphragm in square inches.
The pushrod deflects or flexes upon valve opening and then again just prior to valve closing. As the cam tries to move the valvetrain to open the valve, it has the weight of the valvetrain against it and in the case of the exhaust valve, cylinder pressure also.
The symptoms of bent valves include an engine that won`t start, an erratic engine when idling, lack of engine power, a knocking noise from the engine and excessive exhaust fumes. Engine valves are responsible for controlling the fuel delivery and gas removal in your engine.
A mildly bent rod would affect compression but generally a bent rod will cause engine balance problems at best and serious engine problems at worst. If the rod is truly bent the engine should be disassembled and the rod replaced.
The most common valve failures are bent or broken valves due to contact with the piston or another object in its path. A burnt valve is another type of failure that happens when things go wrong in the valvetrain.
Expect to shell out around $3000 to $5000 for a rod knock repair, depending on all these factors. However, the cost can go beyond $10000 if an engine replacement needs to be done. Rod knock repair requires replacing engine components like gaskets, seals, connecting rod bearings, etc., which are complex and expensive.
Knocking noise: A knocking sound is one of the more common signs of a failing connecting rod, which is why it`s referred to as rod knock. This knocking tends to get louder as you speed up, but it may go away once oil starts to circulate and lubricate the failing connecting rod.