Stock Lifters caused cam scoring... help
05-23-2002, 07:52 PM
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Stock Lifters caused cam scoring... help I have been reading this board since it's inception but have not posted all too much. I want to post my problem here because I respect the opinions of the board members. Here's my problem...
My 2000 LS1 TA started making a tack, tack, tack sound at idle and above about 1 month ago. Relevent mods related to this issue are a T1 cam, Comp 941 valvesprings, hardened pushrods, ti retainers. I took the car in to a reputable shop (f-body guy) in my area. To make a long story short, he pulled the entire valvetrain, everything was OK. We thought it might be the lifters. We pulled the heads. We found two valve guides were very loose causing the valve stem to rub up against the guide. We pulled the lifters and found that a couple of them were collapsed. The rollers on those was scored. We looked at a couple of the lobes on the cam. They were heavily scored. The top of one of the pistons had some metal shavings embedded in it. We drained the oil and found no unusual amount of metal shavings on the magnet. There were no metallic streaks in the oil. I already have new lifters (Comp 850's) going in with new heads (5.3's) and the rest of my valvetrain swapped over. The shavings that were embedded on the top of the piston were cleaned up and it looks good again. The cam will be replaced with a similar one to the T1. The car had over 45,000 miles on that valvetrain that failed. I don't have problems with my 941's, they have been in the car for 2 years, still no breakage. Pre-load was checked during that time and everyting was fine.
The question is: What are the chances that I may have some metal material on any of the bottom-end bearing surfaces? Is there a good way to test without having to pull the pan? Are there any other suggestions other than replacing the lifters, cam, getting the new heads on and see what happens?
Thanks,
-E
My 2000 LS1 TA started making a tack, tack, tack sound at idle and above about 1 month ago. Relevent mods related to this issue are a T1 cam, Comp 941 valvesprings, hardened pushrods, ti retainers. I took the car in to a reputable shop (f-body guy) in my area. To make a long story short, he pulled the entire valvetrain, everything was OK. We thought it might be the lifters. We pulled the heads. We found two valve guides were very loose causing the valve stem to rub up against the guide. We pulled the lifters and found that a couple of them were collapsed. The rollers on those was scored. We looked at a couple of the lobes on the cam. They were heavily scored. The top of one of the pistons had some metal shavings embedded in it. We drained the oil and found no unusual amount of metal shavings on the magnet. There were no metallic streaks in the oil. I already have new lifters (Comp 850's) going in with new heads (5.3's) and the rest of my valvetrain swapped over. The shavings that were embedded on the top of the piston were cleaned up and it looks good again. The cam will be replaced with a similar one to the T1. The car had over 45,000 miles on that valvetrain that failed. I don't have problems with my 941's, they have been in the car for 2 years, still no breakage. Pre-load was checked during that time and everyting was fine.
The question is: What are the chances that I may have some metal material on any of the bottom-end bearing surfaces? Is there a good way to test without having to pull the pan? Are there any other suggestions other than replacing the lifters, cam, getting the new heads on and see what happens?
Thanks,
-E
05-23-2002, 07:57 PM
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Re: Stock Lifters caused cam scoring... help I'm no expert but with 45,000 miles on those 941's I would say you had some valve float at high Rpms which caused piston to valve contact thus collapsing the lifters. In my opinion the bottom end should be fine. A T1 will fatigue 941's pretty quick.
05-23-2002, 09:35 PM
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Re: Stock Lifters caused cam scoring... help
05-23-2002, 10:19 PM
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Re: Stock Lifters caused cam scoring... help </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by cantdrv65:
<strong>I'm no expert but with 45,000 miles on those 941's I would say you had some valve float at high Rpms which caused piston to valve contact thus collapsing the lifters. In my opinion the bottom end should be fine. A T1 will fatigue 941's pretty quick.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The pistons show no evidence as having contact with valves. Valve float does not seem to be it. When the car was dyno'ed a couple months earlier with that kind of mileage on the 941's, multiple runs to 6500 rpm showed no sign of valve float... just a nice curve.
Also when I say scoring, I mean something you can actually feel on the lobes of the cam. Is this even possible? Shouldn't rollers roll on the lobes, with the possibility of damage to the lobe near impossible? Any more opinions/comments please?
<strong>I'm no expert but with 45,000 miles on those 941's I would say you had some valve float at high Rpms which caused piston to valve contact thus collapsing the lifters. In my opinion the bottom end should be fine. A T1 will fatigue 941's pretty quick.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The pistons show no evidence as having contact with valves. Valve float does not seem to be it. When the car was dyno'ed a couple months earlier with that kind of mileage on the 941's, multiple runs to 6500 rpm showed no sign of valve float... just a nice curve.
Also when I say scoring, I mean something you can actually feel on the lobes of the cam. Is this even possible? Shouldn't rollers roll on the lobes, with the possibility of damage to the lobe near impossible? Any more opinions/comments please?
05-23-2002, 10:22 PM
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Re: Stock Lifters caused cam scoring... help </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by C5 Tweaker:
<strong>FYI
https://ls1tech.com/ubb/cgi-bin/ulti...c;f=1;t=004990</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Tha nks for your FYI, but your "scoring" is visual, mine can be felt. <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
The car has always had oil changed every 3000. Synthetic 5w-30, sometimes 10w-30. Oil has always been topped off. Normal maintenance always done on time. Everything was 99.99% perfect and then this occurs. Just weird...
<strong>FYI
https://ls1tech.com/ubb/cgi-bin/ulti...c;f=1;t=004990</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Tha nks for your FYI, but your "scoring" is visual, mine can be felt. <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
The car has always had oil changed every 3000. Synthetic 5w-30, sometimes 10w-30. Oil has always been topped off. Normal maintenance always done on time. Everything was 99.99% perfect and then this occurs. Just weird...
