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Car suddenly started running rough, throwing codes which indicates a manifold air pressure sensor issue. Changed the sensor, problem didn't go away. Wouldn't hold idle, kept stalling.
Got it over to my mechanic; after a bunch of diagnosis he pulled the valve covers and found a broken valve spring. He called me at that point to let me know what was going on. Visions of $$$$ danced in my head
Today he scoped the cylinder and found no damage to piston or bore. The broken spring had screwed its pieces together and held up the valve, preventing any further damage. Replaced the spring and it's running fine. 65K miles on a 2008 LS3.
I would replace all of the springs after an event like this one. Glad it was an easy fix.
If the motor is all stock, then would just suspect the single bad spring to begin with.
Now if the motor was mod'd with say a different cam, or even higher ratio roller lifters, could be that is time to replace all the valves spring instead.
With some after market cams or after market high ratio lifters, there going to be brutal on springs to begin with, and even with the correct replacement springs in play to begin with so they are not coil binding up, they should be replaced every 35K miles like clockwork isntead.
I'm not suggesting that there is a guarantee of another spring failure. Just that the likelihood of this is much higher. All of these springs would have come from the same batch. The fact that it broke on a stock cam is even more concerning to me. To each their own. I would have replaced them all. Who's to say that one was just the worst metallurgy wise defective spring. Big risk over a $300 set of springs.
DCP did you guys pull the head and replace the valve?
Im in the same predicament and was just going to replace all the springs, but im told the valve is more then likely damaged. As I drove abut 5 miles this way. The valve didn't completely drop but did touch the piston im sure .
I think that if they pull the spark plug out on that cylinder, they can put a borescope in there and visually check the valves and the top of the piston for obvious damage.
If everything looks good and you have good compression on the cylinder, you can save the cost of pulling the head off.
DCP did you guys pull the head and replace the valve?
Im in the same predicament and was just going to replace all the springs, but im told the valve is more then likely damaged. As I drove abut 5 miles this way. The valve didn't completely drop but did touch the piston im sure .
My mechanic scoped the cylinder and fortunately there was no sign of contact.
Had the same thing happen to my camaro with a LS3 at idle in a parking lot. Car stalled. I went to start it. No error codes but just heard the piston crash through the valve. Shop looked and it dropped the valve into the 8th cylinder. Valve crashed into the head and cracked it and split the piston in valve then scarf the cylinder. Now trying to find a new engine. Oh. Btw. 60k miles. Original owner. Never rev’d high and completed the full break in cycle and always changed oil on time with mobile 1 5W-30 as recommended. Shop side they used very weak springs for the type of engine. Now going to fight with Chevy on it.
12-03-2016, 04:30 PM
Broken LS3 valve spring - dodged a bullet
