Cobra4B

iTrader: (9)

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.

~Brian

Cobra4B

iTrader: (9)

Nobody can give me any guidance as to how to check for a collapsed lifter w/o pulling the heads first?

chrisfrost

iTrader: (8)

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 .

clubber

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.

b16acrx1988

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.

Rickenbackerman

iTrader: (1)

I had one collapse but it was a short travel Comp lifter. With the valve closed, the rocker was loose. Not sure if it'd be as obvious with a "normal" lifter.



The one on the left - see the puddle of oil?

Cobra4B

iTrader: (9)

Thanks... that helps. I'm going to pull the valve-covers and check each cylinder at TDC. I also read that I can push on the pushrod side of the rocker and see if I can compress the lifter by hand.

b16acrx1988

That is what mine looked like when I pulled it out and it took pulling the heads to finally be 100% sure it turned/collapsed, and it also wipe a lob on the cam.

Cobra4B

iTrader: (9)

Yeah I was worried about that too. Were you able to just replace the cam and lifters and go on about your business? Or, did the metal shavings screw everything up?

b16acrx1988

Replaced cam, lifters, and lifter trays and rolled on. Just make sure to drain the oil well, my filter caught most of everything and my magnetic plug caught the rest.