tap tap tap tap tap tap tap tap tap tapping

[third_shift|studios]

here's the scenerio:

car club was in a parade, naturally revving engines/making noise. I probably went to 6500 and 7000 regularly [imagine doing that about 90 times over the course of a mile] Pulled into a parking lot afterwords to hear i'm the only car with a really high pitch tapping / pinging noise coming from the engine....shut off the car, lifted the hood to cool it off for a good 45 minutes. Turned it on....noise is still there. Oh, someone said that since i'm running fully synthetic oil that could be the problem?

What'd i do? What do i do? what's it gonna cost?

[SShArK>]

maybe a pushrod?

[Ed Blown Vert]

6500 to 7000? :eek: I hope you have an aftermarket drivetrain.
Other wised you floated the valves and they tapped the pistons.

Bent valves.

[third_shift|studios]

local car guru says it's a lifter. anyone know if an LT1 lifter can replace an LS1 lifter?

[Ed Blown Vert]

Stock valvetrain?

[sscrazy]

sounds like a bent pushrod or a bent valve tapping the piston, I would pull the heads off and inspect before you run the car again.

[third_shift|studios]

Stock valvetrain?

yes, stock everything

[keliente]

It sounds like a pushrod to me. It's a light tap/tick noise that increases with RPM...you'll also notice a loss of power over ~5k rpms. I bent a couple a few months ago when I shifted from 3rd to 2nd @ 100mph...whoops!

It is a very easy fix. Remove emissions crap, coil pack brackets, valve covers. Remove rocker arms and the pushrods pull right out. When you roll them on a flat surface you'll notice which are bent - they won't roll smoothly. New pushrods are very cheap. When you reinstall don't forget correct torque specs & loctite on the rocker arm bolts.

[third_shift|studios]

kelli, my savior! thanks-yes thats what it does too, increases with rpm

[GatorSS]

Whoa...! Don't do that kind of revving with the stock valvetrain.

[Ed Blown Vert]

yes, stock everything


Ok, its either bent pushrods or valves.

Don't rev it over 6k on a stock valvetrain. You probably aren't making anymore power over 5800 anyways.

[Mr. Luos]

New pushrods are very cheap.
Aftermarket are cheaper than the GM ones.
If it is only one pushrod bent, PM me. I have one still in wrapper from GM.

If you go with aftermarket pushrods, they won't bend to save your valves. If you go around revving like that you will pop a valve stem with hardened pushrods.
I wouldn't do revving like that WITH an upgraded valvetrain. You are gonna break something doing that. Overall, try not to free-rev.

[LS1Power06]

6500-7000 RPMs? did u mess with the rev-limiter with a programmer or something because to the best of my knowledge it wont let u rev that high from the factory right?

[Zboner]

6500-7000 RPMs? did u mess with the rev-limiter with a programmer or something because to the best of my knowledge it wont let u rev that high from the factory right?

yes he did.

[third_shift|studios]

anybody know where i can get stock pushrods OVERNIGHTED to me?

[Ed Blown Vert]

I have a set, but don't think I can get them out tomorrow.

[sscrazy]

anybody know where i can get stock pushrods OVERNIGHTED to me?
I have a set of used ones out of my ss. also I have a set of rockers. Let me know if you want them i will part with them cheap , make an offer

[third_shift|studios]

I have a set of used ones out of my ss. also I have a set of rockers. Let me know if you want them i will part with them cheap , make an offer

i'll consider those rockers...don't know if we'll need them jsut yet.

[Quil]

How were you able to rev it that high without hitting the limiter?

*EDIT* My bad, completely missed about 5 posts there.

[third_shift|studios]

OK HERE'S THE UPDATE!!!!

so my buddy an i crackopen the valve cover on the passenger side to see that rocker #2 is EXTREMELY loose. So we inspect the pushrod; it's fine. Inspect the rocker; it's fine...oh shit...gotta keep digging-it was a broken LIFTER! it took us like 6 hours of unscrewing, unbolting and digging....we had to take off the manifold covers, the intake and the headders to finally reveal a single broken lifter. It sucked that we had to do all that but it was better than being charged 700+ in time/parts to have the pros do it.

i've learned a lot about this engine just in doing all of this...

[ninobrn99]

sucks bro!! im going to be doing the same thing at the end of the month :( its gonna suck! what did the lifter look like? how do you know it was broke??

[GatorSS]

OK HERE'S THE UPDATE!!!!

so my buddy an i crackopen the valve cover on the passenger side to see that rocker #2 is EXTREMELY loose. So we inspect the pushrod; it's fine. Inspect the rocker; it's fine...oh shit...gotta keep digging-it was a broken LIFTER! it took us like 6 hours of unscrewing, unbolting and digging....we had to take off the manifold covers, the intake and the headders to finally reveal a single broken lifter. It sucked that we had to do all that but it was better than being charged 700+ in time/parts to have the pros do it.

i've learned a lot about this engine just in doing all of this...
Congratulations on finding and fixing the problem on your own. What a great lesson learned. As I've always said, an education will cost you...one way or another (a lot of time or a lot of money or a lot of something).

Good job!

[third_shift|studios]

sucks bro!! im going to be doing the same thing at the end of the month :( its gonna suck! what did the lifter look like? how do you know it was broke??

ok, to test if it's the lifter or bent rod:

1) tear down to expose the valve train.

2) giggle each rocker arm. There is minimal play in each, but the one(s) that rattle(s) the most will be a "problem spot."

3) just to ensure the others are cheked, "Fake-start" the car by just twisting the key on/off in a fast motion DO NOT START THE CAR!!!!! you just want to get that first "pop" of the engine then kill it. This will move all the valves without sending oil through the whole engine. Repeat step 2.

4) remove the "problem-spot" rocker and rod. Wipe off the rod and roll it on a piece of glass or other perfectly flat service. If the rod oscilated while rolling-you're in luck, buy a new 7.400 inch rod.

5)If it rolled smoothly, put it back in and do a "rocker-or-lifter" test by putting a "non-problem spot" rocker in place of the "problem-spot" rocker. If the "non-problem" rocker shifts wildly, then you know you have to dig further and replace the lifter. If it doesn't shift wildly, then the original rocker from that spot is broken.

6) To get to the lifter: remove the air intake/manifold cover. BE WEARY OF THE DELICATE "OIL-PRESSURE SENDING UNIT" JUST TO THE BACK-RIGHT OF THE MANIFOLD!!! Also, there are a few electrical connections and hoses back there. I believe there are 10 screws on the top of the manifold-you can unbolt/remove the front 6, the back 4 are too-long to remove. After all hoses and electricals are out of the way-we left the gas line connected, it wasn't a big problem-lift up on the manifold and begin to pull it forward slowly. Inspect any snags that stop you so that you don't rip anything out. Be careful-that's all i can say, and take a breather if you get frustrated.

7) remove the valve train, the exhaust manifold and header.

8) Inspect the lifter(s) from the "problem spot(s)." In a side-by-side comparison a broken lifter will pour oil out and have a deeped indentation where the push-rod seats.

Good luck, this is a very exhausting/frustrating process that can be done with a lot of patience. DON'T FORGET: you will need to replace the header bolts and the head-gasket. New bolts are to be torqued to 22 ft-pounds.