Metal Propertys

[Pegasus_Red]

I has a question for engineers given that I am in design and yadda yadda

ok, lets say I have a spring, and I sit there and compress it for some 10 years, keeping constant compression with mild temperature changes. After 10 years, I uncompress the spring from its compressed state. Will the spring return to its original position.

thanks for any help

[xamraci]

I has a question for engineers given that I am in design and yadda yadda

ok, lets say I have a spring, and I sit there and compress it for some 10 years, keeping constant compression with mild temperature changes. After 10 years, I uncompress the spring from its compressed state. Will the spring return to its original position.

thanks for any help

Doubtful...what material is it made out of...

[Pegasus_Red]

Doubtful...what material is it made out of...

Im assuming steel, what ever valve springs would be made out of

[ChukiDori]

Like nick said..Doubtful...Springs DO go bad it just takes aloooong time..but especcialy if you compress it for 10 years nonstop.....lol

[xamraci]

Im assuming steel, what ever valve springs would be made out of

What car/engine is it? and It is probably not as TIGHT(loosely termed) as it once was...that i can be almost POSITIVE of...

[Vetteman2003]

I would definitely replace the valve springs.

[CPMaverick]

Yes, it will return to it's original length. No matter the length of time compressed, length and spring rate are unaffected. It's impossible for a correctly designed spring to fail by sitting compressed, no matter how long it is compressed or what the material (though some materials are not going to make a proper spring design)

Yes that's a theoretical scenario but engine valve springs are basically a perfect scenario. They operate entirely within the elastic properties of the material, and engine valve springs in particular have a very high safety factor. They also always see very consistent loading and compression (same thing over and over again). Considering an engine valve spring, they really only fail by cycles and that is a breakage failure. Overloading can occur but it would have to be something like an over-rev to even come close to the safety factor.

The only thing that can make a coil spring 'sag' is a design or material flaw that causes the spring to see values beyond the elastic range. Vehicle coil springs, which are basically the same design, are much more prone to sag because they can corrode (reducing spring diameter) or be overloaded much more easily (pothole, or overloading the vehicle).

The equation for spring rate is very heavily dependent on coil spring wire diameter, it is a multipled ^4 in the equation, so a small amount of corrosion can change the spring rate dramatically.

In short, I wouldn't worry a bit about your springs unless they got corroded/rusty somehow. I'd be much more worried about the valve seats, etc. If the valve has been open for 10 years and the intake/exhaust are not sealed.

[ChukiDori]

+1 to you for the very cool and informative post

[xamraci]

I would definitely replace the valve springs.

Thats what I would be saying...and I would have to compare the spring from that motor to an un-used one...

Charlie is the engineer though:)

[Pegasus_Red]

Well this still just gives me the idea to test it out. No the springs were not rusted by any means. I do how ever think that there might be a lack of oiling present inside the valve guide which has caused for the valve to "stick". I was able to open up the valve by wedging it gently open by pressing on the side of the coil which caused it to open back up. I did shoot some WD40 on the valve stem (through the valve spring) and worked the motor over by hand (yes I can do that on a 1584cc bitches :2xFU: @ 1:7 CR ).
This is on the exhaust side so It did not see direct open air/moisture. I just wanted to check as a friend did explain metal memory to me at one time (you can bend a piece of metal to a certain point, then bend it back to original form, then bend it back to that spot, but if you go over that certain point, failure could occur, but Charlie ftmfw on that one.

P.S.
replacing a valve spring on a vw is a bitch, special tools out the ass.

[helo pilot]

Yea, Charlie knows his shit.

[Vetteman2003]

Valve springs in normal/stock engines will last a long time. Valve springs in engines that have high lift cams will fail more quickly. Depending on the particular engine valve springs can last as long as the rest of the car or as few as 1,000 miles(maybe less). If you want to be sure the springs won't fail you can replace them. If you don't and the spring(s) fail it will probably cost you a motor.

Yes Charlie is The Man

[xamraci]

Yes Charlie is The Man

Pretty much the most consistent declaration you are going to get in this thread...:partydanc

[TooSlowToCare]

Yes, it will return to it's original length. No matter the length of time compressed, length and spring rate are unaffected. It's impossible for a correctly designed spring to fail by sitting compressed, no matter how long it is compressed or what the material (though some materials are not going to make a proper spring design)

Yes that's a theoretical scenario but engine valve springs are basically a perfect scenario. They operate entirely within the elastic properties of the material, and engine valve springs in particular have a very high safety factor. They also always see very consistent loading and compression (same thing over and over again). Considering an engine valve spring, they really only fail by cycles and that is a breakage failure. Overloading can occur but it would have to be something like an over-rev to even come close to the safety factor.

The only thing that can make a coil spring 'sag' is a design or material flaw that causes the spring to see values beyond the elastic range. Vehicle coil springs, which are basically the same design, are much more prone to sag because they can corrode (reducing spring diameter) or be overloaded much more easily (pothole, or overloading the vehicle).

The equation for spring rate is very heavily dependent on coil spring wire diameter, it is a multipled ^4 in the equation, so a small amount of corrosion can change the spring rate dramatically.

In short, I wouldn't worry a bit about your springs unless they got corroded/rusty somehow. I'd be much more worried about the valve seats, etc. If the valve has been open for 10 years and the intake/exhaust are not sealed.

what are you, a fucking engineer?:P

[CPMaverick]

You are supposed to argue biotches