mooty1

I bought a 2002 zo6 about 6 months ago and i love it. Have not had any problems until last friday i was comming home from b.g. and i broke a valve spring . What do you think would cause this .Had dealer install a new one . Someone told this is a problem with 02's.I was wondering if other people are having the same problem and how common it is.
'

Last C5

It does happen a bit, common may be too strong but rare it isn't. Usually it happens with the pre 02s though. If I had one break, I'd be very suspicious of the other 15. Get a set of PAC 1218s or PAC 1518s if you have a cam and stick them in there.

redroket

I had the same thing happen to me shortly after I purchased my 2002. I wish I would have had all of them replaced but like you I only replaced the one? Hopefully it was the only bad one.
Good luck!

Z06_BluByU

for those of you that broke a spring.. were the cars both stock; BONE STOCK or did they have tunes etc?!?!

mooty1

Bone stock here

hpfiend

This is a fairly common problem on 02-03 z06's... apparently with the more aggressive camshaft in 02, as compared to 01, the springs were not up to duty. It seems to occur about every other month to corvette forum members. 04 cars seem to be more immune as I have only heard of one or two I believe that have had them fail.

I as well as numerous others have changed them out for good measure and I at least put a set of fresh LS2 springs (same springs the factory went to in 04) in my bone stock 03 as soon as I got it (GM PN 12499224) First "mod" after the Column Lock Bypass.

Glad to hear you didn't suffer any more damage.

Here are a few more threads on the matter:
http://forums.corvetteforum.com/c5-z...-a-spring.html
http://forums.corvetteforum.com/c5-z...e-springs.html

Diceman9

Last C5....

Do you put the PAC 1218s springs in a bone stock or is it just for the larger cam also? Where do you get the PAC's?

mooty1

It seems this factory defect will be as large as the oil problem in the 01's. Did gm finally accept responsibilty for the defect in the 01's and fix them?

Z06_BluByU

Interesting..

I've asked a service manager how many of these he's seen once.. he told me two.. and both had been tuned.. guess its more wide spread..

Stevo92z28

How is a tune going to affect spring pressure?

Last C5

You can put either spring on a bone stock engine. The 1218s allow for .600 lift (more than enough for a stock cam) and the 1518's, which are more expensive, allow for a .650 lift (in case you add a cam or 1.8 rockers later). Several Forum vendors carry PAC. I got mine from Herron Performance.

ZeeOSix

I need to do this to my 02. It only has 19K miles, but I think it's time to put a whole set of 2004 OEM spring in her for peace of mind.

Any recommendation for the best spring tool to use for this operation?

hpfiend

^^^^ My '03 only had 12K on it when I did it...

On the two rear cylinders on each bank you need to use a quality screw type spring compressor- all of the others can be done easily with a lever type compressor. You will also need a compression tester fitting or at least an air fitting with the same threads as a spark plug hole and an air compressor to hold the valves so you do not have to pull the head. A powerful air compressor will put the engine at top dead center so make sure it is in neutral before give it air.

hpfiend

They could have raised the rev limit with the tune and really gave the springs a workout. But- this has happened on numerous engines that were bone stock and never over-revved- lots of guys/gals report it has happened at idle or cruising on the freeway.

Diceman9

Yep..... mine went out just driving around town. Had no idea what had happened. Real pita trying to figure it out. Dealer was aware of the problem and knew right what to do. (collect my money)

Now that I take it to the road coarse track I want to do all the springs.

Last C5

The Crane valve spring tool is the one you want. Vinci High Performance VHP has them as well as the air line adapter for the spark plug hole.

hpfiend

Nice! Never seen that one before- that may make it a bit easier (especially with an impact ratchet), pretty expensive though....

Nice company! however, on a side note I am not sure their Micronite(sp) treatment of the ring gear was a fair test- if they used a 7.5" 10 bolt coupled with a MANUAL transmission, a 200 shot of nitrous, AND documented 4-5K rpm clutch dumps on STICKY tires I would be more convinced- I don't think it would be so shiny after 40 runs ;-)

ZeeOSix

Did you mean "A powerful air compressor will put the engine at bottom dead center ... " ? Seems like air pressure is going to push the piston down as far at possible (ie, BDC).

Others on the board have mentioned another way to keep the valves in place is to stuff some clean nylon rope inside the cylinder when it's at TDC and valves closed. Seems like an easier, and maybe safer way to go. Would hate to see the air pressure suddenly go to zero and hear the valves drop to the bottom of the cylinder.