sweet-94z28

iTrader: (30)

My 98 T/A is all stock. I was going from second to third at 4000 RPM and it popped out of 3rd after I let my hand off. As soon as I realized the RPM's were going up and the car not going anywhere, It hit Maybe 5000 RPM i think, I backed off it. Now when I start it there is a distinct tapping noise for the first few seconds it is running and then it goes away. Does this sound like a lifter or a pushrod? The oil pressure is perfect, 50 hot idle and 70 WOT. And it makes no noise after the first 5 seconds. It is from the front of the motor, maybe an accessory or something. I might be able to get a video

Irocss85

iTrader: (1)

that does sound like a lifter.

sweet-94z28

iTrader: (30)

I was reading through some old threads and they are suggesting a pushrod

sf35thle

iTrader: (2)

I am thinking it might be a pushrod as well

primer84z

iTrader: (7)

You may have slightly bent a pushrod. Only way to be sure would be to tear it down and check them all. Over reving on a down shift is the worst way because you can mechanically defeat the rev limiter, ******* up your day.

sweet-94z28

iTrader: (30)

How much do those run. It is definitely from the right side of the engine at the front. I am praying that is all it is. This car only has 47K miles on it. I am new to the M6 so hitting gears is still a bit mechanical for me in this car.

primer84z

iTrader: (7)

You can get a full set (16) for around $100.

sweet-94z28

iTrader: (30)

Where at?

primer84z

iTrader: (7)

any of the vendors. I think Thunder Racing has 7.4 hardened ones for like 109 or something. It doesnt matter what brand you get but make sure they are 7.400 length.

sweet-94z28

iTrader: (30)

All I know is that my dad is going to kill me. This is his car until I sell the Z. Are they very hard to change? I don't know a lot about the LSX motors

primer84z

iTrader: (7)

It involves taking the valve covers off, taking the rockers off, pulling the pushrod and putting the new ones in then re-torqueing everything back to spec. Check ls1howto.com or a similar site for more in depth info. Should be in the head and cam swap section.

sweet-94z28

iTrader: (30)

anyone else thinking bent pushrod

Irocss85

iTrader: (1)

that would be your best bet. could always take them out and roll them on a flat surface such as a mirror or large piece of glass. glass table maybe? anyways its very straightforward on the LS1, since the valvetrain is torqued down, not "adjusted" like a small chevy. you just put it all in there, torque down all the rockers, roll the engine over a couple times by hand, retorque them all again and put the covers/coils/wires back on. its a completly diff. story if a lifter is bad.

eyah, I guess overrevving is more often a bent pushrod, but since it goes away when it gets warmed up is the reason I guess lifter. a pushrod isnt goin to straighten back out after the eng. oil is hot, but a lifter will pump up after the eng. warmes up.

sweet-94z28

iTrader: (30)

On a warm start, it does this for about 3-5 seconds depending on how long it has sat. i don't know about a cold start yet. It was only one time that high though too. The car only has 47,500 miles on it. It just had an oil change 250 miles ago too.

sweet-94z28

iTrader: (30)

I wonder if it could be my A/C clutch or the belt tensioner? Some guys have had these tick before (did a search). It sounds like it is at the front of the motor.

TopFlite

I am leaning towards a pushrod since you stated that a few seconds after startup it goes away. If it was a damaged lifter, it would always be tapping until it is replaced.

sweet-94z28

iTrader: (30)

The pushrod to me is the most likely culprit. I do have a code for the A/C clutch so maybe it is going out and doing this? I read about one guy having that in another thread. I could even check for exhaust leaks. After all, it might not be internal.

sweet-94z28

iTrader: (30)

If this is a lifter, how would one overrev or high rev hurt it?

sweet-94z28

iTrader: (30)

Anyone else have any ideas?

Irocss85

iTrader: (1)

well no real answer for that. but a push rod would be bent due to the valve kissing the piston. extremely common with miss shifts and overreving.

you could take the belt off, then start it and see if the noise goes away. that would eliminate any accesories at the front. just dont run for long at all.