What the hell could have caused this???
06-09-2013, 01:26 AM
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What the hell could have caused this??? I was driving my car and heard a loud bang and it died started it back up and it sounded horrible so i had it towed home. So the next day the took the valve cover off and found the #6 intake valve spring compressed all the way down.
so next i went ahead and pulled the head and confirmed what i already thought it dropped a valve.
so my question is what caused it? The spring isn't broken or anything like that the retainer and hardware all looks fine. so I'm kind of lost here? and it wasn't from over revving it let loose at about 6k rpms
so next i went ahead and pulled the head and confirmed what i already thought it dropped a valve.
so my question is what caused it? The spring isn't broken or anything like that the retainer and hardware all looks fine. so I'm kind of lost here? and it wasn't from over revving it let loose at about 6k rpms
06-09-2013, 07:00 AM
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Whats the ICL and LSA on the cam? Did you check PTV when you put it together?
Are there any other witness marks on any of the other pistons? If not then its hard to say why only one cylinder would do that.
I would do the trunion upgrade when you put it back together though.
Are there any other witness marks on any of the other pistons? If not then its hard to say why only one cylinder would do that.
I would do the trunion upgrade when you put it back together though.
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06-09-2013, 08:33 AM
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As requested above, we need all of the build specs. Am kinda surprised that the pistons aren't fly cut, yet there's no sign of valve contact in the limited view we can see w/ that duration, depending on gasket thickness, CR, ICL...etc., would generally see fly cut pistons.
Most probable cause, based on current info. available, is valve float...even @ just 6K max. RPM. That's why it has been asked for you to check spring specs. Even if the intake valves are hollow stem; hollow stem without other issues wouldn't be enough for valve to fail. Regardless, we need all build specs in order for a more definitive answer. Info. regarding gasket thickness & any machining on heads/block are important.
BTW, dual springs are generally good for 20K-25K miles & then should be changed.
Most probable cause, based on current info. available, is valve float...even @ just 6K max. RPM. That's why it has been asked for you to check spring specs. Even if the intake valves are hollow stem; hollow stem without other issues wouldn't be enough for valve to fail. Regardless, we need all build specs in order for a more definitive answer. Info. regarding gasket thickness & any machining on heads/block are important.
BTW, dual springs are generally good for 20K-25K miles & then should be changed.
06-09-2013, 11:44 AM
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Whats the ICL and LSA on the cam? Did you check PTV when you put it together?
i will post a pic of the cams spec sheet.
Are there any other witness marks on any of the other pistons? If not then its hard to say why only one cylinder would do that.
there are no other marks on any other pistons at all
I would do the trunion upgrade when you put it back together though.
i will post a pic of the cams spec sheet.
Are there any other witness marks on any of the other pistons? If not then its hard to say why only one cylinder would do that.
there are no other marks on any other pistons at all
I would do the trunion upgrade when you put it back together though.
about 3500 miles and they are severe duty stainless valves
As requested above, we need all of the build specs. Am kinda surprised that the pistons aren't fly cut, yet there's no sign of valve contact in the limited view we can see w/ that duration, depending on gasket thickness, CR, ICL...etc., would generally see fly cut pistons.
i had ls9 gaskets and the heads were milled a little bit
Most probable cause, based on current info. available, is valve float...even @ just 6K max. RPM. That's why it has been asked for you to check spring specs. Even if the intake valves are hollow stem; hollow stem without other issues wouldn't be enough for valve to fail. Regardless, we need all build specs in order for a more definitive answer. Info. regarding gasket thickness & any machining on heads/block are important.
BTW, dual springs are generally good for 20K-25K miles & then should be changed.
i had ls9 gaskets and the heads were milled a little bit
Most probable cause, based on current info. available, is valve float...even @ just 6K max. RPM. That's why it has been asked for you to check spring specs. Even if the intake valves are hollow stem; hollow stem without other issues wouldn't be enough for valve to fail. Regardless, we need all build specs in order for a more definitive answer. Info. regarding gasket thickness & any machining on heads/block are important.
BTW, dual springs are generally good for 20K-25K miles & then should be changed.
