REading all the scare stories about broken valve springs I decided to change
them out in my 03 Z with 20K miles. Got the yellow springs from GM parts
warehouse. My son has a GTO and has done this job many times, so we
did it together. Got it all buttoned up and it sounded great...I drove the 40
miles home later and at a light I heard a valve tapping...by the time I got to
the last 500 feet...the car was really running rough...I shut it down and
rolled home into the driveway...I took off the valve covers and found one
rocker arm bolt about an 1/8 inch loose..the one next to it was slightly
loose. I retorked them all and buttoned the car up. Seems to be running
OK...but now I am scared this will happen again. We did tork all the rocker
bolts to 22 ft lbs....so I don't know why this happened. Someone said we
should use lock tight on the bolts....any suggestions?

Also while I have your attention...my heating fan is making a noise like there
is a leaf stuck in there....anyone else have this problem?

 

I'm pretty sure I know why you are having this problem. I too have an 03 Z, & about 2 months ago, I changed my stock springs out too. I had read all the horror stories of v/spring failure with our LS6 Z motors.

I also did some research as to how and which method I was going to tackle this job, by myself. (Very first time).

I used the TDC method instead of airing up the cylinders, when removing & installing the springs.
Once all the springs were on, I made sure the motor's #1 cyl was @ TDC., of the compression stroke.

I then put all the push rods on and installed all the rockers along with the bolts. (hand tighten)

As mentioned above, with the motor in this position. Tighten ( Exhaust rocker bolts) 1,2, 7, 8 all to 22 lb ft.
While still in this position, tighten (intake rocker bolts) 1,3, 4,5 all to 22 ft.lb.

Rotate the crank 360 degrees. Tighten the following (exhaust rocker bolts) to 22 lb.ft. 3,4,5,6.

Tighten the following (intake rocker bolts) to 22 lb.ft. 2,6,7,8.

Your now done. I bet you tightened all the rocker bolts at the same time? I had read that you were never to tighten down a rocker on an OPEN VALVE., & to do so is bad practice.

I'm pretty sure the GM service book does not call for any loc tite to the rocker bolts.

Now in regards to the noise your hearing from the blower fan. I suggest pulling the squrrel cage. Once you have this pulled & upon inspection, I would venture to say that mice has made a home in this area or there is some other obstruction (part of a seal, etc.)

Good luck.

 

Thanks for the reply...we did not exactly do this..but we did rotate the crank for rockers that were on the cam. How did you find TDC?

 

With the valve covers off and the plugs out. Turn the engine over by hand, turning the crank pulley. Looking at cyl.#1, see when the intake valve spring is compressed. Continue turning the crank untill the piston comes up to the top.
I used a flashlight & mirror to look into plug hole.
You can rock the crank back & fourth as needed untill you see the piston @ the top.

I used a box end wrench 15/16",about 14" long that had about an inch off set (kick) to it, & stood on the pass side(more room) & turned the crank pulley bolt from there. If working w/someone, you could have them turn the motor over, ever so slightly with the ignition key.
Once I found TDC I marked the pulley w/painted dot & alligned it up at a certain point on the horizonal steering rack.

 

you could also if 2 people, use a screw driver stick it inside the cylinder and have the other guy turn the motor while you feel with the screw driver when it is at tdc

Steve

 

I am the OP's son. This is what I did, since I wasn't sure how to find TDC without the cover off. I tighted all the rockers down regardless of position first. Then I remembered the rockers that had the springs compressed (valve open). I had him turn over the motor until they were closed, then I loosened and retorqued them. Done it this way about 10 times in my GTO with no problems with about 30k on the cam. In hindsight, its probably not a good idea because it still stresses the threads if you tighten a rocker bolt with the valve open. We will just use the TDC method next time. I could also just write down which valves are open at time of removal...then when you put it back together only torque those rockers...spin the motor over with the fuel fuses pulled, then torque the remaining ones.