Checking for a collapsed lifter - How? What do look for?
2001 LS6 with 123,xxx miles. Last 4k have all been track use. I bought the car with 118,xxx miles specifically to build into a racecar. The engine is stock other than fresh yellow springs, an air intake, LS4 high volume pump with 42lb relief spring, and an ATI super damper.
2nd TimeTrial session at VIR on Saturday the engine just isn't making the same power and oil pressure is a few PSI lower than normal (40-45 vs. 50+) and I hear a sharp tapping.
Pretty sure a lifter has taken a dump. I had planned on pulling the heads this off-season and swapping them, but I guess the timetable has been accelerated. I pulled the valve covers at the track and couldn't find anything wrong. No broken springs or puked needle bearings.
What else can I do/check to verify a failed lifter before I pull the heads? If a lifter was collapsed wouldn't I have a pushrod with a bunch of play? When/if I do pull the heads what can I look for on the lifters themselves as a sign of failure?
Thanks for any input.
__________________ 2001 Quicksilver Z06 - NASA ST2/TT2 racecar Panoz GTRA - LS1 & full restoration 2008 Nissan Titan
If You have a collapsed lifter You will only see play if that valve is closed or if the p-rod pops out ,,,,,,,,,so You need a repair manual or google adjusting valves and turn engine around to TDC and check the appropriate lifters 4 play , then turn crank 360deg and check the remaining 1's ,,,,,,,,,but I can tell You that You're lower oil pressure is not likely caused by a lifter ,,,,,,,,,more likely a bearing or the oil pump .
__________________ In the life of the average auto engine , the crank revolutes roughly 450,000,000 times before the engine shows significant wear .
At 6000 rpm's the pistons of an LS based engine with the stock stroke of 3.622" are only moving at 37.5 mph !
Well, as far as how to check, chrisfrost probably is right but the symptoms you describe are the exact symptoms I had when I had a lifter take a dump. Good luck from here, I had no idea what the problem was on my car and pulled the engine thinking it was worse, so don't do that.
You can pop the valve covers off and slowly roll it over watching each valvespring, I had one collapse/turn and I really couldn't tell by doing it, but that is one of the things to look for. It was really hard to tell for me, I didn't lose compression, but when it happened I knew something went wrong, it started tapping lost power and went into limp mode until I restarted it. If the pr's are straight, the valvesprings look good and the rockers are fine the best bet is to just pull the heads. On a side not my mileage was almost exactly the same.