Bent pushrod, what is the cause?!

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jpsfmc1229

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So i recieved the car about a month ago.. 225 1971 Dodge Dart Swinger. when i got it, there were two bent push rods. I replaced them, took the head off, cleaned it, and replaced the valves. started it up again after putting it all back together. then i went to adjust the valve clearance and saw the new push rod bent in the same spot as last time! what could be the issue!?
 

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I had 2 on my engine shortly after getting it on the road. My guess is old gummy motor oil. I swapped some out for junk yard ones. Another one bent before the first oil change, replaced again and it's been fine for 5+ years...
I have a full set you can have for shipping if you want from a 71 engine that I took out for a magnum swap. Let me know.

Matt
 
Usually when they bend it's because of some kinda interference issue. Piston to valve is the first thing that comes to mind. When I first got my 65 Valiant years ago, it had a skip. Turns out it was a bent pushrod. I pulled it out, put it on a vise and beat it straight with a ball peen hammer. Put it back in and adjusted the valves and never had another problem with it. Go figure.
 
Rocker may have been way loose and it may have gotten bent when it popped off the rocker. Mine were bent a little further down and not so sharp of a bend, but far enough one was hitting the drool tube :D
 
Yeah, the engine oil was pretty nasty, and there was a lot of sludge and gunk when I took the head off. Ill replace the rod or straighten it out and try again. hopefully the oil change helps..
 
Almost certainly caused by the push rod popping out from under the rocker and getting jammed under the rocker arm... Why .... If the motor is a stock build then it is basicly too loose as someone already mentioned and either a result of bad adjustment - or a bad lifter that is collapsing and allowing the rod to come out...
 
Old gas will often cause a valve to stick. Once valve won’t move something has to give, often it’s a push rod.

Stumper:
or a bad lifter that is collapsing and allowing the rod to come out...
Click to expand...
It’s a 71, and photos appear to show solid lifter rockers; no collapsing.

Over revving can bend push rods.
 
Could the springs be too stiff for the pushrods? They look new, w/ green dye, and no telling what the prior owner used. Ditto for the cam lift. Insure they don't approach "closed coil" with the valve full open. It requires some headroom, especially at high rpm where the spring coils could start bouncing into each other.
 
When motors sit a long time, (Ive had a couple slants do the same exact thing) the valves stick closed and the pushrods bend. I usually replace or straighten the rods and soak the top end as well as possible with marvel mystery oil and it usually fixes it.
 
Rockerdude said:
When motors sit a long time, (Ive had a couple slants do the same exact thing) the valves stick closed and the pushrods bend. I usually replace or straighten the rods and soak the top end as well as possible with marvel mystery oil and it usually fixes it.
Click to expand...
I sent you a PM
 
hey guys thanks for the input. I graduated college this weekend so ive been busy with other things besides the car. however i did re bend the pushrod straight and will try to throw it back together and see again. the only thing that confuses me is that i took the head off and cleaned it and replaced the valves.. figured it would not be sticking anymore. Ill give it another try though and let you all know how it goes.
 
Did you replace the timing chain and gears?? Dad n I did that and when we were setting valves with engine on stand we bent push rods. Crank sprocket had 3 keyways(to adjust timing) and I put it on in the wrong one.
 
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