bent push rods?

carnestruck · Aug 6, 2012

So I had a timing chain break and cam sprocket snap in half. After changing the belt found out I had to dead cylinders. #4 and number#8. I decided to take the head off myself and take it to mechanic to do the valve work but when I took the valve cover off I found two bent push rods. From the front of engine on passenger side they were #5 and #7. I am concerned now that if the push rods were bent and I mean bent that if I get the head repaired or get new one that there may be other damage to the engine that could damage a new or repaired head.

I wanted to get some thoughts on this. What causes the push rod to bend that way or what other parts of the engine may be affected or do the valve take most the impact from the push rods? I am no mechanic by any means but just trying to make a wise decision here and looking for input

Thanks

fox racer · Aug 6, 2012

carnestruck said:
.... What causes the push rod to bend that way or what other parts of the engine may be affected or do the valve take most the impact from the push rods?...

my bet is on valve to piston strike = bent push rods... you would be lucky the rods bending took all the brunt of the contact and not damage the piston crowns. only way youre going to find out about the carnage is pulling the head... worse case scenario, rebuild or replacement motor.. everything from heads, cam, lifters, etc will have to be inspected. lifters are cheap enough to just replace regardless.

TazRango · Aug 6, 2012

The 5.2 is a clearance engine.. Meaning you don't smack up the valves when a timing chain breaks.. Something else went horribly wrong there if you have bent up pushrods. It's likely you over-revved and the valves floated. That can easily result in bent pushrods. I take it you didn't notice any busted springs?

jmaack727 · Aug 6, 2012

^ that

they are non interference.

9t9-5.2 · Aug 7, 2012

The 3.9, 5.2, and 5.9 are interference engines, pushrod and valve damage can occur especially if there is a manual trans behind it. There is nothing in the valvetrain to close the valves if the chain was to break.

TazRango · Aug 7, 2012

9t9-5.2 said:
The 3.9, 5.2, and 5.9 are interference engines, pushrod and valve damage can occur especially if there is a manual trans behind it. There is nothing in the valvetrain to close the valves if the chain was to break.

Uhh. No they aren't, genius. Only the "point 7" engines are interference. Go back to bed. :jester:

9t9-5.2 · Aug 7, 2012

TazRango said:
The 5.2 is a clearance engine.. Meaning you don't smack up the valves when a timing chain breaks.. Something else went horribly wrong there if you have bent up pushrods. It's likely you over-revved and the valves floated. That can easily result in bent pushrods. I take it you didn't notice any busted springs?

TazRango said:
Uhh. No they aren't, genius. Only the "point 7" engines are interference. Go back to bed. :jester:

Explain the earlier comment. Pistons can not contact the valves in a non-interference engine, yet valve float causes bent pushrods how?

Is your psychosis substance induced?

TazRango · Aug 7, 2012

I'm not even going to waste my time explaining it to you, dickhead. Go look it up yourself.

9t9-5.2 · Aug 7, 2012

TazRango said:
I'm not even going to waste my time explaining it to you, dickhead. Go look it up yourself.

Because you can't.

Don't forget to take your meds.

carnestruck · Aug 7, 2012

Ha Ha

I appreciate the laugh this morning guys. So what is really going on non interference or not? I have the head off and taking to machine shop today. The pistons do not look like they have any marks. You think I should check those out? and what about the cam shaft? does this not hit the push rods?

TazRango · Aug 7, 2012

9t9-5.2 said:
Because you can't.

Don't forget to take your meds.

Ugh. Crawl back under your bridge, troll. Don't come back until you learn the basic workings of an engine.

carnestruck said:
I appreciate the laugh this morning guys. So what is really going on non interference or not? I have the head off and taking to machine shop today. The pistons do not look like they have any marks. You think I should check those out? and what about the cam shaft? does this not hit the push rods?

The 5.2 is NOT interference unless they have been stroked, decked, and/or have a really high cam/high ratio rockers installed. In stock configuration, the piston does not come all the way to the top of the bore, so there is no way it can smack the valves even when wide open - as evidenced by you not seeing any impact marks. And if the piston HAD hit those valves, it would've bent the valves and broke the stock rockers before it bent the pushrods.

(I'll explain this to you, the troll can watch and maybe learn something :jester

When you rev too high, the springs can't rebound fast enough to keep tension on all of the valvetrain components, and you get slack between the components (cam-lifter-pushrod-rocker-valve). This is called float. When the valves float, the components (which normally all move together in one fluid motion) begin to separate and smack into each other. This in itself can bend the rods and cause other damage. Without tension on them, the pushrods actually start to bounce around in their bores (put a pencil in a paper cup and shake it around), and if the gap gets wide enough, the bottom tip can actually ride up out of its dimple to the edge of the lifter. If it catches the edge, it gets pushed up too far with a lot of force, and it bends. Even if the lifters are able to pump up and compensate quickly enough to keep the pushrod from riding the edge, once the engine slows down they can't deflate quickly enough to keep the pushrod from traveling too far - which has basically the same result.

9t9-5.2 · Aug 7, 2012

:blahblah::blahblah::blahblah:

TazRango said:
genius

:blahblah::blahblah::blahblah:

TazRango said:
dickhead

:blahblah::blahblah::blahblah:

TazRango said:
troll

Time to double up on your meds.

TazRango · Aug 8, 2012

9t9-5.2 said:
Time to double up on your meds.

9t9-5.2 · Aug 8, 2012

Word for word, from the factory service manual:

CAUTION: When tightening the rocker arm bolts, make sure the piston in that cylinder is NOT at TDC. Contact between the valves and piston could occur.

How long ago were you diagnosed with BRP?

TazRango · Aug 8, 2012

Yeah? Thats funny because I don't see that 'word for word' phrase in my copy of the 1998 FSM. Nor are there ANY steps that refer to installing or removing the arms in any specific order, nor is there any step that involves turning the crankshaft after each cylinder, as there is in the 4.7 (which IS an interference engine) FSM. :jester: You're wrong dude. Give up and slink back under your bridge, lest you embarrass yourself further.

9t9-5.2 · Aug 8, 2012

You're right...I made it up. :bow::bow::bow::bow:
BTW, there is a reason for the caution note on the page you posted. Read it and think about it.
You really should get in to see your therapist, it is apparent your meds need adjusted.

TazRango · Aug 8, 2012

You're just too dense for words. Yes. there is a FANTASTIC reason for that caution. To keep you from bending pushrods due to the lifters being overinflated. Notice it is mentioned AFTER the step telling you to tighten all rocker bolts in no particular order. What did you think it meant?

IT IS NOT AN INTERFERENCE ENGINE. PERIOD. The OP even said there are NO contact marks on the pistons or valves - which if the piston hit the valve with enough force to bend the pushrod there absolutely would be. You're NOT going to win this one, so you might as well go back to your bridge. And you can make alllll the therapy/meds jokes you want, they just make you look even more retarded.

KTHXBYE.

9t9-5.2 · Aug 8, 2012

TazRango said:
You're just too dense for words. Yes. there is a FANTASTIC reason for that caution. To keep you from bending pushrods due to the lifters being overinflated. Notice it is mentioned AFTER the step telling you to tighten all rocker bolts in no particular order. What did you think it meant?

IT IS NOT AN INTERFERENCE ENGINE. PERIOD. The OP even said there are NO contact marks on the pistons or valves - which if the piston hit the valve with enough force to bend the pushrod there absolutely would be. You're NOT going to win this one, so you might as well go back to your bridge. And you can make alllll the therapy/meds jokes you want, they just make you look even more retarded.

KTHXBYE.

You still make no sense. Is that what this is about, you feel you need to "win"? Good luck and keep trying.

It isn't a joke, you need to get your psychosis under control, at the least you will have an aneurism, worst case...we read/see you on the news about going postal.

TazRango · Aug 8, 2012

You seem to be the only one who doesn't understand, so guess what that means? :huh:

9t9-5.2 · Aug 8, 2012

You appear to ignore the bold caution from the manual I posted, which is a newer version from the 98. :huh:

Will the State of Kansas let you posses weapons?

bent push rods?

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