Bent pushrod: Why and tips for replacing

steamboy05

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Hello everyone, I recently picked up this 1966 New Yorker, and unfortunately she has a bent pushrod on the #7 intake. The car had been sitting for at least six years before my father and I bought it. The car drove the seven or so miles back to our house. If anyone has any tips on replacing the pushrods in a stock 440 I’d really appreciate it. My dad is also interested in why this might’ve happened, so please chime in if you have a hunch why.
P.S. Should the rocker arms have this large of a gap? Neither my dad or I are very familiar with big blocks yet.

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Usually this happens because the engine has sat idle for and extended period. The valve guide rusts up and starts to seize. When the engine is started up, there is excessive friction and that bends the push rod. The advent of no lead fuels made this problem worse as there was no lead residue to help lubricate the valves. Low phosporus additive oils also contribute to this problem. I would suggest giving the valves a shot of a good penetrating oil before starting the engine. Most of the time a bent puish rod can be straightened in a vise but if it badly bent replace it.

Dave
 
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That uses '68 and older type push rod..
At NO time should a bent pushrod be straightened and used..
They are a hollow tube and once bent they are weak and will in
all probability bend again..
Seeing how nasty the inside looks as Davea Lux says, got gummy
and valve was stuck, pushrod bent when motor was turned over...
Once motor got warmed up stuck valve became able to move more freely....



.
 
I had non-running 383 where PO installed timing chain wrong. All push rods bent or broke.
Good time to check for nylon teeth on cam sprocket. Replace timing chain and gears if nylon teeth found.
 
My god do not turn that engine anymore, you have in all probability seized components in that engine be it from time sitting and environment that it has been sitting idle in for some time. Very careful assessment of this engines condition needs to be done before you turn it over again.
 
that particular rocker is well worn out and I’m guessing by the crud present all over the top of that engine it’s not the only one. Original pushrods means original cam and lifters which likely means original timing chain and gears. That’s not to say it couldn’t be made to run but I would at least pull the rocker shafts and all the pushrods for inspection and check the timing chain for excessive slop. I may have some of those old style pushrods in one of my buckets of scrap metal. If it can be made to run without doing much more than that I would say it’ll be tired at best.
nice looking car though! :thumbsup:
 
I'm going to agree and disagree with most of what has been said here.

First, the rocker is kind of typical and that isn't where you would gauge wear. The holes for the rocker shaft are punched out roughly with plenty of clearance for the shaft, so the gap is normal. What does wear and will need to be inspected is the area that actually rides on the shaft. In other words, the rocker shafts will need to be pulled and cleaned to do that.

Second, I don't believe these pushrods are hollow. That said, I'd replace rather than straighten IF you can find one. Those are used in the '67 and older cars and are made to fit the lifters. Should you replace the cam, the easier way is to use a '68 up style lifter and pushrod.

Third, yea, it's probably from a valve being hung up from sitting. That valve may still be hung up....
 
That looks like a fairly decent car to work with!

It's already been driven 7 miles home, so there's no need to concern about damage, what's done is already done.
Biggest place to look for wear is where the rocker arm rubs/rolls on the valve tip.
Rockers on a bigblock are 'sloppy', where they fit on teh shaft, and also side-side.
As mentioned, a valve got stuck. I suspect the cam can push the valve open with more force than the spring can close it, so the valve sticks open. What then probably happened was the pushrod retracted and the valve didn't, and the pushrod fell from the rocker, and got pushed against somethign immobile on the next pass.

I've had quite a few engines like this that still had life left in them. I've seen them with sludge 10x worse, too.

Check timing chain slack: remove the dizzy cap, put a socket on the crankshaft bolt and rock the engine to/fro 30deg or so to see how quickly the distributor rotor responds. This is the easiest time to check this, as you'll be taking the distributor and oilpump driveshaft out next.
Put some clean oil in it, if you're on a budget use oil-change oil from your daily driver if it's a well-maintained engine.
Do an oil pressure test - install a gauge at teh port at the rear of the engine (there are 2 of them), remove the distributor and oilpump drive shaft, and spin the oil pump the correct direction with an electric drill. (removing the shaft generally takes LONG needlenose pliers and can be a PITA in a neglected engine) Pay attention/make notes on where the slot was pointing, and at what angle the slot was pointing when it came free (it rotates as it is removed due to the gear teeth)
Run the drill enough to watch for oil flow out of the rocker shafts and onto the arms.

If oil pressure and the flow to the rockers is OK, and if the engine didn't smoke on the way home, presume it healthy enough to invest in it further.
Replace the pushrod and timing chain and plan on some frequent oilchanges (every 2-300 miles?) to help clean it up. You could swap a pint or quart of ATF into teh new oil to help clean, ATF has more detergent than oil. You could also use Marvel Mystery oil. I would avoid any 'motor flush' treatments as cleaning sludge out too quickly can cause it to go someplace harmful and block oil flow.

When you have the rockershafts off, be aware they must reinstall properly, there's an oil hole that must be in the correct location or it will reduce flow to teh rocker arms/valves. (you can google that)

Another thing you can do - if the rocker arms/shafts are removed, insert an airline fitting into the sparkplug hole and pressurize the cylinder. You can rap each valve tip with a small deadblow hammer and see if you get a resounding pop of air out of the port, and if the valve closes. This will help find if any other valves are sticky, and the cylinder's air will help blow out any debris that was laying around the valve seat (although that likely blew out on your drive home). You may find most of the valvestem seals are broken or missing, so you can squirt some oil toward teh valve stems before rapping the valves if you wish. Would be a good time to change seals, they are cheap. You can also listen for escaping air to determine if you have any valve sealing issues - if you have a burned valve it will be a constant rush out the intake port or the tailpipe. In an engine like this one, you should expect to hear blowby leaking past the rings into the crankcase. Don't get hung up on that - the main thing to check is for large leakage out the valves.

An alternative cleanign method:
Get the shopvac out and a small screwdriver/small brush and clean as much sludge out as you can (within 1-2 hour timeframe is sufficient) - make sure any chunks you break loose get vacuumed out immediately - don't lose them inside the engine. Do the heads and lifter valley.
A squirt-bottle of kerosene, diesel, mineral spirits, etc can be used to rinse stuff away. Old toothbrushes are economical.
Drain the oil pan, put the plug in and rinse some solvent down the lifter valley. You can let it soak and then drain it, or let it run out as you go.
When you change the timing chain, the front edge of the oil pan will be available for pan-rinsing also.
Don't use your your favorite/clean shopvac for this unless you plan to clean it afterward. (I have a 'junk' shopvac specifically for such work)

Whichever you do - plan on doing some frequent oilchanges for awhile. You can always pull a valve cover to look for cleaning progress as you go.

Rock Auto will be a good place to look for individual pushrods, valve seals, and possibly the rocker arms if you need any.

Keep us posted on your progress!
 
if it were me, i would give the top of the valve a few good whacks with a hammer , install a new pushrod and see what happens. the worst that will happen is you'll bend another one , or it might be fine.
 
That looks like a fairly decent car to work with!

It's already been driven 7 miles home, so there's no need to concern about damage, what's done is already done.
Biggest place to look for wear is where the rocker arm rubs/rolls on the valve tip.
Rockers on a bigblock are 'sloppy', where they fit on teh shaft, and also side-side.
As mentioned, a valve got stuck. I suspect the cam can push the valve open with more force than the spring can close it, so the valve sticks open. What then probably happened was the pushrod retracted and the valve didn't, and the pushrod fell from the rocker, and got pushed against somethign immobile on the next pass.

I've had quite a few engines like this that still had life left in them. I've seen them with sludge 10x worse, too.

Check timing chain slack: remove the dizzy cap, put a socket on the crankshaft bolt and rock the engine to/fro 30deg or so to see how quickly the distributor rotor responds. This is the easiest time to check this, as you'll be taking the distributor and oilpump driveshaft out next.
Put some clean oil in it, if you're on a budget use oil-change oil from your daily driver if it's a well-maintained engine.
Do an oil pressure test - install a gauge at teh port at the rear of the engine (there are 2 of them), remove the distributor and oilpump drive shaft, and spin the oil pump the correct direction with an electric drill. (removing the shaft generally takes LONG needlenose pliers and can be a PITA in a neglected engine) Pay attention/make notes on where the slot was pointing, and at what angle the slot was pointing when it came free (it rotates as it is removed due to the gear teeth)
Run the drill enough to watch for oil flow out of the rocker shafts and onto the arms.

If oil pressure and the flow to the rockers is OK, and if the engine didn't smoke on the way home, presume it healthy enough to invest in it further.
Replace the pushrod and timing chain and plan on some frequent oilchanges (every 2-300 miles?) to help clean it up. You could swap a pint or quart of ATF into teh new oil to help clean, ATF has more detergent than oil. You could also use Marvel Mystery oil. I would avoid any 'motor flush' treatments as cleaning sludge out too quickly can cause it to go someplace harmful and block oil flow.

When you have the rockershafts off, be aware they must reinstall properly, there's an oil hole that must be in the correct location or it will reduce flow to teh rocker arms/valves. (you can google that)

Another thing you can do - if the rocker arms/shafts are removed, insert an airline fitting into the sparkplug hole and pressurize the cylinder. You can rap each valve tip with a small deadblow hammer and see if you get a resounding pop of air out of the port, and if the valve closes. This will help find if any other valves are sticky, and the cylinder's air will help blow out any debris that was laying around the valve seat (although that likely blew out on your drive home). You may find most of the valvestem seals are broken or missing, so you can squirt some oil toward teh valve stems before rapping the valves if you wish. Would be a good time to change seals, they are cheap. You can also listen for escaping air to determine if you have any valve sealing issues - if you have a burned valve it will be a constant rush out the intake port or the tailpipe. In an engine like this one, you should expect to hear blowby leaking past the rings into the crankcase. Don't get hung up on that - the main thing to check is for large leakage out the valves.

An alternative cleanign method:
Get the shopvac out and a small screwdriver/small brush and clean as much sludge out as you can (within 1-2 hour timeframe is sufficient) - make sure any chunks you break loose get vacuumed out immediately - don't lose them inside the engine. Do the heads and lifter valley.
A squirt-bottle of kerosene, diesel, mineral spirits, etc can be used to rinse stuff away. Old toothbrushes are economical.
Drain the oil pan, put the plug in and rinse some solvent down the lifter valley. You can let it soak and then drain it, or let it run out as you go.
When you change the timing chain, the front edge of the oil pan will be available for pan-rinsing also.
Don't use your your favorite/clean shopvac for this unless you plan to clean it afterward. (I have a 'junk' shopvac specifically for such work)

Whichever you do - plan on doing some frequent oilchanges for awhile. You can always pull a valve cover to look for cleaning progress as you go.

Rock Auto will be a good place to look for individual pushrods, valve seals, and possibly the rocker arms if you need any.

Keep us posted on your progress!
Oil is not going to flow out to the rockers unless the engine is rotated while priming as the oil passages only line up to reach the heads at different points in the revolution.
 
I'm going to agree and disagree with most of what has been said here.

First, the rocker is kind of typical and that isn't where you would gauge wear. The holes for the rocker shaft are punched out roughly with plenty of clearance for the shaft, so the gap is normal. What does wear and will need to be inspected is the area that actually rides on the shaft. In other words, the rocker shafts will need to be pulled and cleaned to do that.

Second, I don't believe these pushrods are hollow. That said, I'd replace rather than straighten IF you can find one. Those are used in the '67 and older cars and are made to fit the lifters. Should you replace the cam, the easier way is to use a '68 up style lifter and pushrod.

Third, yea, it's probably from a valve being hung up from sitting. That valve may still be hung up....
My thoughts are after spending a fair amount of time recently weeding through 2 collections trying to complete 1 good set is that the ones that were that wallowed out had some material at the contact point with the shaft worn away.
 
My thoughts are after spending a fair amount of time recently weeding through 2 collections trying to complete 1 good set is that the ones that were that wallowed out had some material at the contact point with the shaft worn away.
If everything is working correctly, the top portion of the rocker shaft hole will never contact the shaft. I think we can agree on that.

I went through a ton of rocker arms back many years ago, (back when I was drag racing) including brand new ones bought over the parts counter at my local dealership. We had to run these in stock class. That hole size was all over the place. It's a rough hole, pierced by a punch and die somewhere in the process. The important part has always been the bearing surface to the shaft. Wear on this surface is easy to spot, and usually accompanies obvious wear where the rocker arm contacts the valve.

We ran legal "stock" cheater cams with fast ramps that were tough on rocker arms, with pushrods often pierce the rocker if you weren't careful. I even think Chrysler offered a heavier version, made from thicker material, for a time, but I went for the stock ones that were a little lighter.

My point being that you really can't determine if there is any wear until you take it apart, clean and inspect those two surfaces. Given the sludge in the OP's engine, yea, there's gonna be some wear, but how much would be the question.
 
Oil is not going to flow out to the rockers unless the engine is rotated while priming as the oil passages only line up to reach the heads at different points in the revolution.
Good point, I was writing all of that while imagining something I haven't done in quite some time.
 
Let me guess, did you pour ~5 gallons in the tank and start driving? If so all the dried out original gas semi liquified and ran through the carb. Once in the intake manifold it condenses when you shut off the engine. It then dries into the best adhesive money can buy. Short story, never run an engine in a car that has been sitting for years without thoroughly flushing the fuel system.

Remove the tank and either replace it of have it cleaned inside. Also flush the fuel line all the way to the carb. You will probably need to rebuild it too. I suspect there is more than one bent pushrod. Since you're in for a penny, in for a pound, take the time to replace the timing chain too. Odds are it's rather sloppy now and waiting to jump a tooth or two and really screw up the engine.

i made this mistake and all intake pushrods bent after I started it for the first time, let it run for a while an shut it off. Next day the pushrods bent and I had to pull the just rebuilt heads and take them to the machine shop and have the valves pounded out, guides knurled and reassembled. Needless to say the gas tank went to the junk yard. An expensive learning experience. It was also a 66 Chrysler. 2dr model though.
 
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