I was driving when I heard a loud banging engine noise. I pulled my passenger side valve cover off and noticed that the top 3" of one push rod was floating in the head and the rocker was out of alignment. There is some minor damage to the end of the valve stem, as if a corner was mashed slightly. I cannot locate the rest of the push rod and it doesn't appear to be visible as I look through it's opening in the head. Where is the remaining piece? Could it be in the bottom of the oil pan and if so is there a possibility that it has done any damage to the cam? I was able to start the car up before I pulled the valve cover off and it does run but not well. Can one pushrod be purchased and replaced? Also, how critical is the minor metal damage to the end of the valve stem? I can post pictures if necessary but I wanted to know if ANY damage is considered critical? I really need help, thank you.

 

why did the pushrod break, this is what you need to find out. did a valve seize, did you mechanically over rev(downshifting) did you over rev using the gas pedal??


and yes you can replace just one pushrod

 

the rest of the pushrod is probably laying in the lifter valley. you need to pull your intake to fish it out. i'd want to know why it broke too.... did you stick a valve?

 

I don't know why the pushrod broke.... I didn't overrev the engine, I was just driving normally. The only thing that I can think of is that the pushrod has a bit of an abbrasion mark on it which I think could either be a manufacturers defect or a spot where the pushrod was hitting the side walls of it's opening. I noticed that the other pusrods come awfully close to the side walls as well. I am no machinist so I don't know exactly what it is suppossed to look like. I have never been happy with the shop that did the rebuild so I don't know if it's faulty work on their part. Either way, I guess I will have to remove the intake manifold to check it out but there are still so many unknowns. If the pushrod is not in the valley, did it damage the cam when it fell down and is the end of the valve ok with the bit of a mashed corner?

 

If it was me I would pull the cam in the least to make sure nothing was damaged. pull and check your other pushrods to make sure none are bent. your faulty rod may have been bent and it was rubbing and that is what caused your failure. Make sure to marry up the pieces of your rod to make sure you dont have chunks floating in your motor.

 

From one AZ guy to another. I just went through this and hear is what happened to you as well.
I recently had my 289 rebuilt. Mine is also a 66, and in 65 and 66 ford used a rocker arm that is kept in place by the puShrod. There are holes in the head that the pushrod slides into to go to its happy home and meet the lifter. If you notice, the holes have flattened and narrowed sides. It is actually a slot not a "hole".

I if you remove and inspect your other rocker arms you will see wear patterns. However, they will not all be the same. So if the guy that assembled you engine did not put the rockers back onto the same valve that they came off of then the worn area on the rocker will not match the worn surface on the top of the valve. As you drove the car, even it was only a short time the top of the valve will wear the old rocker differently. Then your rocker will come loose, allowing it to bounce on the pushrod and bend it or break it.
Even if you did not notice it I guarantee that before this happened there was a bit of lifter noise coming from the engine.

If you look over me previous posts you will see where i inquire about lifter noise and adjustment. Then a few days later you will see where i am posting pics of my messed up lifter, bent pushrod and messed up rocker mount studs. Read the posts and you will get an education.

Hear is how to fix it so you will never have the issue again and your car will perform even better. I will even tell you how much each thing costs.
-Remove intake
-get that piece of pushrod out.
-remove heads, you will now need to get the valve repaired. The rocker was most likely riding at an angle on the rod for a while. You will have a groove worn into the stud. It needs to be replaced. Here is where you get to upgrade your heads.
-Buy a set of ARP threaded rocker studs$47, Comp Cams pushrods (hardened is better)$80, and a set of Comp Cams Guide Plates $16, and a set of full roller or roller tip rockers ( Comp Cams roller tip $180, Magnum full rollers $230)
-take your heads to a machine shop have them, trim the stud girdles to fit the added hieght of the studs and tap them. good thing is they dont have to drill them out cuz the hole is the correct size 3/8". Then they need to resurface the damaged valves or replace them. Next they need to drill out the slots that the pushrods install into, otherwise the new pushrods will bind in the guide plates. THIS SHOULD COST $100.then you take the heads home.
-Buy new Fel-Pro head gaskets and install the heads
install new pushrods and your new Comp Cams Roller Rockers.
Adjust valves and re assemble the intake and top of engine.

LAST BUT NOT LEAT.... BURN RUBBER... GAS IS CHEAP AGAIN

IF YOU NEED LET ME KNOW. I JUST DID THIS. I LIVE THE WEST VALLEY AND I CAN HELP.

 

If your car was a 67 or newer it probably not have happened. Newer heads used a "rail type rocker" the rockers have flanges on the sides to keep them aligned.

 

Here are my threads when i went through it. And the guys that helped me.

https://mustangforums.com/forum/clas...lve-noise.html

https://mustangforums.com/forum/clas...yone-help.html

https://mustangforums.com/forum/clas...tud-issue.html

https://mustangforums.com/forum/clas...at-helped.html

 

You're going to have to pull the intake to get the other part of the pushrod out. Make sure the lifter is still in it's bore too. It might have popped out. Most of the time pushrods bend, not break. Sounds like it was worn. The early heads need hardened pushrods. Sounds like some binding or rubbing somewhere. Try and get some pics of the broken end of the pushrod.

BTW, unless the piece is reallt small, there's no way for it to fall into the oil pan.

 

Wow, thank you all for the information, especially MonsterBilly and everyone who helped him! All the articles are great and i'm happy to have them to reference to. I'm not an experienced engine builder so I have to rely on the advice from other people. I'm not happy because this is going to be more expensive than I had expected but..... hey that's the way it is with these things. The one thing that I would need help with is a recommendation to a good machine shop. I've only used one and they did a $#!tty job on my current engine so I need a good recommendation of one here in the valley. BTW, what kind of performance gains did you notice with the new threaded roller rocker arms over the old stamped originals?