Push rods keep bending
 

Sup guys,

Me and a couple of my friends just rebuilt a 5.0 mustang. Everything worked fine. We started her up and it worked fine for 20secs and heard a rattling noise. We turned her off and started to pull parts of it. We found out that the push rods are bending. So we thought maybe the old ones were just too old. Bought brand new ones and they did the same. We are trying to look for titianium ones but we can't find them. Can someone tell me why the rods are bending? thanks for the help
By the way he put in new valve springs that are comp. Its has a big spring inside that a medium spring and inside that a small spring. 3 layer springs

99 cobra

RE: Push rods keep bending
 

or not

99 cobra

RE: Push rods keep bending
 

Did you check for piston to valve clearance while putting it together?
Did you check the cam timing?

RE: Push rods keep bending
 

Clay them pistons if this is a radical cam.That rattling noise was most likely the sound of valves kissing the pistons.In fact im almost able to guarantee it.Pull the heads off and im betting you see it.

RE: Push rods keep bending
 

what do you mean clay them pistons if its a radical cam?



99 cobra

RE: Push rods keep bending
 

put clay on the pistons, and rotate the engine. the valves will leave an imprint in the clay.

RE: Push rods keep bending
 

And that would show what? Sorry but i never heard of this before.

99 cobra

RE: Push rods keep bending
 

for some reason though the rods are also loose. Even when we torque the rocker arms the rods move side to side. the cam he put in has a .498 lift. any comments


99 cobra

RE: Push rods keep bending
 

How much duration? Any reliefs in the pistons? What size valves?

RE: Push rods keep bending
 

Hey dude, did you use a stock camshaft or an aftermarket one??? if you used an aftermarket cam with a higher lift your valves may be hitting your pistons when you turn your engine over.. he said to clay your pistons. this means you put model clay on top of the pistons with the heads on and everything put together and rotate the engine with a socket and ratchet. then remove the heads and see how thick the area is where the valve mashed the clay. if they squish the clay flat you dont have enough piston to valve clearance and will have to correct the problem or you will bust a piston, bend a valve(s), or bend pushrods, or all three. if you used a stock cam, your cam timing may be off and the valves can hit the pistons then too. anyhow, i've rattled off enough now.. later.

RE: Push rods keep bending
 

Perhaps I should clarify what I meant when I asked if you checked for piston to valve clearance, or if you checked the valve timing.

When you put an engine together, you should check (and recheck) that you get the timing marks right on the timing gears (or chain), especially if you added a new cam with higher lift. AND you should always check to be sure that there is clearance between the valve and the piston. You do this by placing clay on top of the piston in the general area where the valve is above it. Doesn't have to be very much. Then you place the head(s) on (with gaskets) and assemble the entire valve train assembly. Once assembled, rotate the motor by hand (rachet and socket) a few rotations to get all the valves to move a couple of times. Once this is done, remove the heads and see how much the valves have flatten the clay, and measure the thickness where it did flatten it. This will be your piston to valve clearance. There should a spec that you need to follow for your particular motor, which should be provided by the cam manufacturer.
Even if you reused the same cam, if you get the the cam to crank timing off by any chance when you reassembled it, it may allow the valves to open too early, and meet the piston at the end of it's exhaust stroke. This will definately make a rattling noise, and bend your rods.
At this point, to me, it sounds like you better repull that motor and check your pistons and valves as well. If you've got bent pushrods, more than likely you've got bent valves as well. Just hope you didn't crack a piston or 2 in the process.

I know it's probably not what you want to hear, but you've got to get to the root of the problem before you do anymore damage here.

RE: Push rods keep bending
 

aint that what i said???

RE: Push rods keep bending
 

Yup, pretty much. I just elaborated on it more :D Remember, I'm a newbie here, so I can get away with it (or at least I hope I can :eek:)

Hmmm, you're a newbie as well. So maybe we can both get away with it [&:]

RE: Push rods keep bending
 

you have too much spring pressure....thats a junk e cam I think.....also are you guys just tighten the valves down without rotating the engine to adjust them right...