Bent pushrods=Bent valves???
Thread Starter
Launching!
Joined: Nov 2005
Posts: 240
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From: Thornton, Colorado
Bent pushrods=Bent valves??? I bent my pushrods a while back, had them replaced and the motor runs smooth and feels fine. Just talked to my buddy's mechanic and he said that if I bent to pushrods then the valves are probably bent too and that you can really only tell on a leakdown test. I didn't break a spring when this happened (somehow) but I did bent one of the pushrods to about a 30 degree angle. Does this sound right? Wouldn't it run like total sh*t if the valves were bent?
Normally i dont think so... I've fixed several guys cars who bent the pushrods bad on M6 stick cars ...almost always from missing a gear REAL bad while racing. None hurt anything but the pushrods.
Thread Starter
Launching!
Joined: Nov 2005
Posts: 240
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From: Thornton, Colorado
Originally Posted by Ping King
how would it bend the valves?
If you're running hardened pushrods, you could bend a valve on a bad misshift. If you're running stock pushrods, good chance that's all that bent. The buddy's mechanic probably doesn't realize how flimsy our stock pieces are.
I bent my pushrods very badly and it didnt hurt the valves at all. I did a leakdown test and it checked out ok. But that wasnt good enough for me I pulled the heads and checked. Better safe than sorry.
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Thread Starter
Launching!
Joined: Nov 2005
Posts: 240
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From: Thornton, Colorado
Originally Posted by Viper
If you're running hardened pushrods, you could bend a valve on a bad misshift. If you're running stock pushrods, good chance that's all that bent. The buddy's mechanic probably doesn't realize how flimsy our stock pieces are.
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Launching!
Joined: Nov 2005
Posts: 240
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From: Thornton, Colorado
Originally Posted by LS144
I bent my pushrods very badly and it didnt hurt the valves at all. I did a leakdown test and it checked out ok. But that wasnt good enough for me I pulled the heads and checked. Better safe than sorry.
When you top out a gear and accidentally shift into a lower gear instead of a higher one, you mechanically overrev the motor by quite a bit. The anemic stock valvesprings simply can not control the inertia of the valvetrain at this speed. The result is that the lifters jump off the cam lobes since the spring isnt strong enough to keep it down, with the lifter off, the valve is still further down and floating when a piston comes up and smacks the valve. This sends a sharp hit through the valvetrain, which is usually enough to collapse and bend the pushrod under the inertia of the lifter. Usually the valve is much stronger than the pushrod, so the pushrod bends to absorb the shock. I would say that of all the people who bend stock pushrods due to an overrev, 95% or more have no problems with the valves.
Originally Posted by Ping King
so valve float would cause bent valves, not a bent pushrod.
Thread Starter
Launching!
Joined: Nov 2005
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From: Thornton, Colorado
Originally Posted by GuitsBoy
When you top out a gear and accidentally shift into a lower gear instead of a higher one, you mechanically overrev the motor by quite a bit. The anemic stock valvesprings simply can not control the inertia of the valvetrain at this speed. The result is that the lifters jump off the cam lobes since the spring isnt strong enough to keep it down, with the lifter off, the valve is still further down and floating when a piston comes up and smacks the valve. This sends a sharp hit through the valvetrain, which is usually enough to collapse and bend the pushrod under the inertia of the lifter. Usually the valve is much stronger than the pushrod, so the pushrod bends to absorb the shock. I would say that of all the people who bend stock pushrods due to an overrev, 95% or more have no problems with the valves.
I've Broken one pushrod before.. the mechanic only changed one though.. so does that mean the others might still be bent?? i dont hear a really loud ticking like before my one pushrod broke.
When I bent pushrods, I also bent 5 valves. Most weren't bent enough to even notice with the car running but one was bent enough to cause a miss at idle (threw a code and everything).
Mark
Mark