froggy47

I have a 2004 z06 with 55k miles.

On another thread where a used 2004 z06 was recently acquired one of the posts recommended checking the valve springs (among other things). The car has 5k miles, a lot of autox use.

It got me to wondering if I am neglecting mine. Should I be checking them every 5k miles? That's 10 times I missed checking them (by miles).

Or, my preference, if they are not broken or showing some/any symptom, leave them alone.

Since there is no adjustment, what are you looking for? Broken spring?

I tend to over maintain, but I leave the (stock) engine buttoned up unless there is a reason to open it up. Frequent oil changes (5k avg) are standard.

Street/autox/track in order from most use to least.

I do know of certain model years/motors where a known issue has surfaced with springs, rockers, etc.

AFAIK there is zero on the 2004 LS6, maybe the earlier ones. I think I recall 2004 (at least, maybe earlier) got "better" springs.

What do you guys say?

RX-Ben

Probably not the most urgent thing to keep an eye on. What is your redline and how often do you miss a downshift (mechanically overrev)?

froggy47

Stock red line (6500) I had one mech over rev which I "caught it" before the clutch was all the way out, maybe went to 7k.

In general I think the guys that like to do this a lot have more time on their hands than I do so it's easy & makes you feel good (sorta like oil change every 3k miles on a car that's driven once a month to the golf course.)

What about using a mechanics stethoscope to give a listen every so often? Would that show up a broken spring?

I'd be up for that.

RX-Ben

I guess I don't see the value in checking on these b/c if they are bad (broken) you are going to hear it with your ears or otherwise notice something is amiss.
Just checking every 5k is hoping that you are checking in at the time that a crack has developed, that you can see, but that hasn't yet lead to a full broken spring (and the chances of that coinciding w/a 5k check seem tiny).

froggy47

Bad Karma

I suppose you could pull them and have the spring pressure checked? But if you pull them just replace them it's cheap enough. For me it's just one of those items on my replace them every couple of years list.

MarkDFW

I'm told this depends on the cam and how you drive the car.

I have a decent size cam, daily drive my car, and beat it for all it's worth around 10 times a year on the track. Local aftermarket shops tell me to change the springs once per year. Even if you don't drive it, there is tension if you have a big cam. Bigger cam and/or harder driving = more frequent change so really depends based on what I'm told.

froggy47

That's making some sense. I'm stock everything but I do redline it when I compete.

Still, if one breaks, does it grenade the engine or usually just start clicking & you fix it?

Mark2009

You check the valve spring pressure with a tool. There are versions of the tool that will check the springs while they are still on the car.


If the valve springs get weak then you can have valve float at less than redline RPM. If you have valve float over an extended period of time you can break things like valves. If a valve breaks and falls into the combustion chamber, it may be game over for that engine (especially if it has cast pistons).

waddisme

After breaking one last year, and going thru all the crap to clean it out, it is worth changing frequently. I was on an every other year with mine, but couldn't make it thru the second year without it breaking. It had 17 track days with a 242/660 cam. It is a annual thing for me regardless of number of track days now.

froggy47

Thanks guys good info!

UstaB-GS549

I was worried about springs a few years ago. It looked like there were a few spring failures on 2002 LS6 engines. Some happened at idle or low revs and the car ran poorly with no damage except the spring. Some high RPM failures damaged engines. These engines did not have a lot of miles on them if I remember correctly.

I went with stock yellow springs for around $60 for the set plus another $100 or so for the Crane tool that allows removal of springs on car with air pressure holding valves closed.

Time to replace the springs was a few hours, but a lot of that time was wiping down parts and worrying about dropping a valve into the chamber. Dropping a valve is probably not possible if the piston is anywhere near TDC. I used the rear wheel to turn the engine over with the trans in 6th gear.

I think the current GM springs are blue. If your cam is stock, I would not bother with aftermarket springs.

From a fatigue standpoint, your springs have seen a jillion cycles by now, and if they were going to fail due to bad metallurgy or surface discontinuities, they probably would have done so by now.

There is no way of inspecting for fatigue damage that I know of. You might get lucky and find a crack with magnaflux or x-ray if it is just starting, but the odds are similar to winning a lottery.

froggy47

sean.b

semi big cam here (585/575 228/232) and i run dual springs just for the peace of mind. that way if one dies, the valve wont lose tension and ill just have a very noisy pit stop in my future. no way in hell am i checking them without reason more than 1-2 times a year, though.

didnt know about that checking tool though, glad i lurked this post!