I was running down the road hit 5 grand and heard a pop and then valve tapping. When I put in in the garage and pulled the valve cover a pushrod was shot into the rocker the one right next to it was snapped in half laying in the valley. The pushrods were number 7's intake and exaust. What caused this to happen?

 

One pushrod was probably a little bent and at 5k it just let go, taking the other one with it.

Sometimes rockers wear a hole in the from gaulling on the the ***** at the end of the pushrod.

Sometimes a lifter will come apart.

Its tough to tell where the problem lies without a good visual inspection.


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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

R.I.P. #3
My favorite quote about D.E. "He can see air"

 

The parts only have 3k on them. The pushrod couldn't of took the other on out. One went up through the rocker and stayed there and the other bent in one spot and snapped in the other and then fell into the valley. The lifter was also laying in the valley.

 

Did the lifter come apart??

Is the valvetrain stock or have you switched out any other parts. (self aligning rockers, etc.)

What year/engine/valvetrain combo are we working on??

I have seen an extreme case where the guides in the heads were worn out for the pushrods and they allowed the pushrod to wobble. This in turn caused the tips of the valves to wear off to the side and all this slop ended up causing the pushrods to leave the vehicle.

Basically there wasn't anything left to guide the valvetrain and keep all angles and geometry correct. At high RPM things got a little wigly.

Just a shot in the dark.
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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

R.I.P. #3
My favorite quote about D.E. "He can see air"

[This message has been edited by Engineboy (edited March 25, 2001).]