ozzyman

I have a 2000 Z28 Convertible, powered of course by an Ls1 and an automatic trans. Ocasionaly i hear what sounds to me like a valve rattle. I bought the car 4 mos ago and have changed the oil every 3000 like i am supposed to with Castrol 20/50, it now has a grand total of 40k miles. A friend told me he read an article that said some of the late model engines have this characteristic. My question is... is my friend correct and should i be worried. I mean the car has great power and will still run 0 -100 in just under 10 seconds, the noise just has me a little worried. I have also read that the valve spring desin is kind of faulty and they will loose temper quickly, could this be the cause of my noise?

Z28COnrad

I think I know the sound that you're talking about. I posted this same question a few days ago and the response I got was that some cars just seem to do this and no it doesn't hurt anythign. The sound I have sounds like a very light rattling, the way I described it was like a coke can pop-top gettin sucked in the engine and bouncing around a lot. So if this is the sound then no worries ... also 10 seconds seems awful quick to run 0-100 with a stock Z28 convertible.

Knowklew

0-100 10 seconds........stock.....no way!

ozzyman

I have a friend in the service dept at the dealership. He put a highway patrol computer in it! and ive put in an slp cold air setup

camaroz28_97

if you run 1-100 in 10 seconds that means you STOCK car will run the 1/4 in 10 or at least 11 seconds. sorry but im going to have to call

Knowklew

My friend put extra grease on my muffler bearings when i bought mine too.

HScott

Sheesh...C'mon guys, don't be so hard about the numbers.

Anyway, I bought a 98-z28 (50k miles) just a few weeks ago and had a similar sound, particularly when hitting the gas while below 2500 rpm or so. I've done two things since then, and my sound is completely gone:
1) Switch from regular unleaded gas to Shell V-Power
2) Had the car serviced (fuel injectors are the only possible contribution)

I suspect more #1 than #2; I also found other message boards that siad as much.

Lastly, two boards I check (weeks ago) answered questions to this sound saying "Don't worry about it...it's a characteristic of the LS1 engine."

AL SS590 M6

It's probably the 20-50 oil....... These motors are designed to use 5-30 oil and thicker oil is NOT going to flow as well causing oil starvation to some or all parts.

twozs

i agree with al, who told you to change to 20 -50 .that oil is too thick deffinitly starving

Greed4Speed

Just an FYI: You more than likely gained nothing from the B4C (law enforcement package) computer. http://web.camaross.com/forums/showt...&highlight=b4c

The SLP cold pack may have picked you up 10-15 hp. Probably more like 10.

So, I'd say you're waaaaay off on that 0-100 in 10 sec concept.
Not even a stock Z06 can pull that off.


I'd also agree the 20w-50 oil is too thick. 10w-30 is the thickest I'd run and I live in Texas. Thicker oil is not automatically better. You actually make more power with thinner oil.


As for the noise, run some Seafoam in the car and get some GM top end cleaner to spray in your intake. Follow the directions on the cans. Change oil and plugs afterwards and see if that helps. It could also be that the different computer is tuned too lean (doubtful) or the MAF is dirty. Some TB cleaner will clean the MAF. DO NOT touch those wires, spray it at a distance so the full force of the blast won't be hitting the wires.

The only sound I know of that the LS1 is prone to is from piston slap. You'd only hear that when its cold, goes away when it warms up. Its a deeper sound than valve clatter.