How can I tell if I have bent pushrods? I've hit the rev limiter 2 or 3 times since I've had my car, and have heard that hitting the rev limiter can bend the pushrods. So if I have done so, how can I tell?

 

sometimes you can hear an abnormal noise but unless they're seriously bent, you usually won't hear anything or notice an SOTP loss of power.

the best way to check is to pop the valve covers off, pull the pushrods out and roll em across a nice smooth tabletop or something.

EDIT: also, while it's possible, usually hitting the rev limiter a couple times won't bend pushrods. what tends to bend them much more often is a mechanical over-rev (as in trying to shift into 4th at redline and hitting second... , aka the infamous 3-2 upshift.)

 

Like he said...

Most of the time.. you can hear a bent lifter if it's really bad. It's a 1hr job to pull em all and test them.

Might as well drop a hardened set in there while you're at it.

 

I thought that was the whole point of haveing the rev limiter? To keep the car from getting damaged? I have hit the rev limiter a total of like 5 times now and i dont hear any lifter noise or loss of power etc. So hopefully they are fine. I think the reason they get messed up during the shifting process is that you go from about 2k to 6k and that jump in rpms makes things move faster then they should with such an abrupt force put on them.

 

how can u tell if u have a bent lifter
cause i think i do?
i did the infamous 3-2 upshift
my car sound like it knocks

 

You're more than likely hearing a bent pushrod. Lifters don't bend... they collapse.

 

The rev limiter can't stop an engine from being mechanically over-revved from downshifting too far. Ya, it'll try, but once the clutch is engaged and the gearing of the gear requires X RPM at a given speed in a certain gear, then something has to spin or break. So if you're doing 75 mph and you accidently drop it into 2nd instead of 4th, it has to spin at whatever crazy RPM it would take for 2nd gear to do 75 mph, or break something.

 

usually a somewhat ugly combination of both...

 

what happens when u collapse a lifter?

 

Pretty hard to bend a lifter. But pushrods bend sometimes. And not generally when hitting the rev limiter. Done it many times myself with no ill effects.

 

well im not sure about slight damage but i can tell you from a friend's experience what happens if you CATASTROPHICALLY collapse one.


my friend did heads and t-rex in his car. 3 days later, he got on it and collapsed a lifter so badly that he froze it in the lifter bore....the cam came around at 6500 rpm and whacked the roller right off the bottom of the lifter.

the roller bounced around the whole bottom end of the motor and tore up everything while the pin that the roller rotates around bent back when it snapped off and took a nice chunk out of the block at the bottom of the lifter bore.....

in short, EVERYTHING was shot....the heads were alright but almost the entire shortblock including the block itself, plus the cam were totally destoryed...

also, if you collapse a lifter, you'll KNOW it. i was next to him when his let go and it made the most awful metal on metal "clacking" noise you could imagine....sounded like he threw a rod!

 

Actually what you've described is a lifter freezing or sticking in the lifter bore. Bad news for sure.

Collapsing a lifter is when the piston inside the lifter doesn't hold the pushrod up anymore (inside a hydraulic lifter is a piston which is pumped up by oil pressure. It will give a certain amount so that valve lash adjustments aren't necessary. When it won't hold the valve open anymore it is said to be collapsed.) and it'll sound like a major loose rocker, but seldom does catastrophic damage to the motor.