Z06ster

This thread deserves "Public Service Announcement of the Year" award... thanks Skyavonee

skyavonee

Latest #'s are 136 reported failures, and 52 submitted build dates.

NBM LS1 M6

Having read through this thread, and the one below cited in the same. . .

. . . . I have determined that I should spend the peace of mind "insurance" money to replace my valve springs.

Since I live in California, I am interested in what other mods I should consider having done at the same time if I want to gain some horsepower. Is there a cam out there--smog legal in California--that I should consider. Is there another fifty horsepower somewhere?

I have a 2002 Z06 with what I believe is an early build date. The month and year are 5/02. The last six digits 130xxx.

I purchased the car a year ago with 36K miles. It will turn 42K miles in the next few days. Not my daily driver. I have another older Corvette also.

Having read through the two threads cited, I am inclined to buy a known quality set of new valve spings. There was at least one post that caused me to believe that GMPP valve spings might not be the best choice. Can I trust valve springs made in Mexico?

TIA

ZeeOSix

5/02 is actually a late 2002 model year build. They started building model year 2002 Vettes in June of 2001.

Get some PAC 1518 valve springs. Probably one of the best ones out there IMO.

NBM LS1 M6

A late build date made sense to me from the beginning. However, I was looking at the VIN #s cited in the thread(s), and they made it seem to me that the VIN was early.

NBM LS1 M6

Who makes these? From where are they available? I have a couple shops. One of them will do the install.

Laser Guided

Interesting findings, definitely an excellent contribution.

NBM LS1 M6

When all is said and done. . . .

How many of these valve spring failures were cars that were bone stock and never run at the drag strip, never driven on a road coast, never modded, never super-charged, never modded with NOS, never run on an autox course, and always maintained to the letter of the maintenance schedule?

skyavonee

In all seriousness, what is the point in buying the highest performance production car GM had ever produced [at the time of manufacture] if you can't beat on it every once in a while without it blowing up?

And again, if it were a usage error that led to the demise of the valve springs, then the distribution over build months should be fairly constant, instead of exhibiting the spike that it does.

skyavonee

PAC is the manufacturer; 1518 is the model. Texas Speed is one vendor that sells them, and I'm sure a quick internet search would uncover others.

Black 02

Anyone who has a car fitting this description needs to sell it immediately. What a waste.

halp

This is great info and lots of work went into gathering all the information.
Does this take into account that there were 28,388 Z06s built between 2001 and 2004, but 16,932 of them were 02 & 03s. That means that 60% of the Z06s built were 02&03s. If you take out the 01s with the smaller cam then 75% were 02&03s. It would stand to reason that they would report more valve spring failures. Also, what percent of members on this forum have what year Z06s and how many of the failures were in stock motors?

Production #s from Corvette Action Center are:

2001=5773
2002=8297
2003=8635
2004=5683

Probably still is a valve spring issue, but now I can understand why more in the 02&03 cars

skyavonee

My third plot, which is really the most telling of the three, takes into consideration production numbers to compare failure rates among the different groups. Thanks for the input, though.

skyavonee

Another one from the Danger Zone bites the dust...

This one was an early build '03 model.

zeevette

My 02Z was built in 11/01, and I replaced the heads with TFs about 2005. Whoever bought my stock heads, got them complete; but I believe the stock springs had a pink stripe.

skyavonee

Could they have been orange? I've definitely seen a picture of orange-striped LS6 springs before.

IIRC, I've also seen or read about: blue stripe, solid blue, yellow stripe, solid yellow, and bare metal. I don't think anyone knows for sure how many different springs were tried on the LS6...

zeevette

Yeah, orange is possible, but I was thinking a faded red.... i'm a little colorblind, too.

skyavonee

I've updated the charts with the latest results, and I slightly expanded my VIN range estimate of the highest risk group. Details can be viewed on the first post.

skyavonee

And yet another engine from the Danger Zone has grenaded.
People, LISTEN - 75% of all 02-03 valve spring failures have occurred in the following range of VINs:

2002: 20000 - 36000
2003: 00001 - 09000

These are the last 5 digits of the VIN. If you own a Z06 in this range, and it still has the stock springs, please replace them! A solid budget-minded choice is the oem LS2 springs, and a good higher-end aftermarket spring is the nitrided PAC 1518.

halp

Wish more owners would report mileage and build date. Only 47 reported mileage and if you average it out its about 57,000 miles. Only 7 were below 30,000 miles and 17 were above 70,000 miles. looks like a spring could go at any time but higher mileage does contribute. Is there a way to find out how many Z06s were built by month in 02 and 03?