Valve springs vs time compressed

Any metalurgists, engineers, or rocket scientists here that can explain why valve springs do or don’t lose strength from being compressed over sustained periods of time. This is a 2001 Chevy 350 engine that has been sitting in storage. The cylinders were fogged and all other storage considerations were followed. What’s the real story on replaceing valve sprrings that have been sitting partially or fully collapsed for any extended period of time? Is this just an old wives tale, or do they really get sacked out, and if they do, what is the length of time that would be considered safe as far as no weakness or damage caused to them?

Colapsed should read “compressed” in line #5

I have trouble believing that, given all the 30, 40, 50+ year old cars that get driven infrequently with no valve spring problems.

Probably not as much weakening as an engine that has been started and cooled over 200,000 miles. Heating and slowly cooling is one way to soften metal. The rule is to run the engine and fix things if there is a problem.

All engines (with valves) have the valves under varying degrees of compression depending on the cam lobes positions, all the time. Most engines aren’t run more than one to two hours a day. So, they are static 22 to 23 hours a day. They do fine not losing any appreciable (if any) spring tension.

Thanks for your answers. You have ALL made good points.

My concern is that as opposed to an engine that is run once a month, or maybe once or twice a year, this one was NEVER even turned over NOT ONE TIME in many years. This left some of the valve springs “parked” in the fully compressed position with no relief.
I would have felt better if this was a once a month, or once a year driver, where the engine had a chance to stop in a different place and put the load on different springs occasonally.

My friend who co-owns this “barn find” brought up the point of factory crate engines that may sit for years before being sold.

Is the “crate engine” theory a valid argument for not worring about replacing the springs??
Is there a point (time wise) where springs DO LOSE their strength when fully compressed?

I really don’t think you have anything to worry about, except, of course, if the springs were actually defective. They don’t need ‘relief’. Here’s another reason not to worry: when you turn off the ignition on most cars, the crank frequently stop at the same spot, so that engines valve springs will be undergoing just the same conditions as what you describe, and they don’t seem to hurt.

Is this some super-high power engine? If it’s way off the ‘normal’ scale, then who knows what’s up with it.

I think there are a dozen guys here and quite a few hundred for the asking, who will tell you “yes, we got the old Model A, John Deere, you-name-it started and no, the valve springs were just fine after sitting 40, 50, whatever years”. And yes, you can find a metalurgist who will show you in precise detail and microns why they “lose their strength”. Have the words “tired springs” ever been spoken? No. Well, maybe for old mattresses.

I agree that the engines stop in just a few places when shut off.
Small block Chevy engines all seem to stop in 3 places. All the Chevy flywheels, and the automatic flex plate starter ring gears that I have seen have ONLY 3 PLACES that show excessive wear from the starters engageing them. They are just totally ruined in 3 spots while the rest of the ring gear is pristine. I have never understood why an 8 cyl. engine only stops in 3 places. Maybe I will pose that as a ques. on here later, although if you or any one else knows, please share this info…

The engine is nothing special as far as a wild cam that would need special valve springs. It is a 2001 Volvo Penta “marinized” Chevy 350 engine/ 300 h.p.
Volvo Penta buys them from Chevy and “marinizes”<—(What the heck does that mean LOL) them to survive in the marine environment, salt water,etc.
It is in the back half of a 27 foot boat that caught fire in the galley and burned off the front half, but the fire never got within 10 feet of the engine. The hour meter survived the fire and it reads 46 hours. They bought it back from the ins. company, winterized it, new engine oil, fogged the cylinders with oil, etc. and put it in storage.
Their reason for not starting it occasionally was that this would scrape the “fogging oil” off the cylinder walls, and would also “acidify” the engine oil from all the heating and cooling cycles, and any exhaust gasses that could get by the rings and into the crank case oil.
If the co-owner or I were to keep this eng. and use it, I would not worry about the springs as we would just monitor it for valve noise, and replace them if necessary, but IF we sell it I don’t want the buyer to suffer a broken spring and a sucked valve 6 months down the road. This is where co-owner and I have differing opinions.

While I’m not a metallurgist, and have no desire to be, I will say that over the years I’ve never seen much of a problem with weakened valve springs even on engines that are much older and have sat for far longer than this one.

There are a couple of methods of determining if a spring is weak, or less likely, broken.
An engine with a weak valve spring will have a tendency to have a slightly rough idle. (lope, stumble, skip, or whatever you prefer to call it)
A vacuum gauge can be connected to an intake port and a weak spring will show up on a vacuum reading while the engine is running.

A V8 engine will have a piston at top dead center with the crankshaft at 4 distinct places: 0, 90, 180 and 270 degrees. When you turn off the ignition the engine will continue to rotate from momentum until friction and compression stop it. It’ll stop within a few degrees of one of the same 4 places as the piston rises compressing one of the 8 cylinders.

For the same reason, a V6 engine will stop within a few degrees of the same 3 places.

Thanks for your post Jay. I agree they should stop in 1 of 4 places. However, every 283-350 flywheel/flex plate starter ring gear I have looked at only has 3 spots that show excessive wear, where the starter drive gear is engageing it. The only thing I can think of would be that all these engines had a low compression cylinder causing the 4 “parking places” to become only 3. Do you think this is a possibility? Have you seen a s.b. Chevy ring that showed excessive wear in 4 places?
What are your thoughts on the valve spring question?

Thanks for your post ok44.
I have one of the “vacuum guage diagnosis charts” with about 18-20 pics of vac. guage readings for diagnosing a multitude of engine problems, which we will probably use when we start it up.
I didn’t want to even start it without replacing the springs, untill I read all of the posts on here. I am satisfied now, since everyone is in agreement. Now I am waiting for a “metalurgist” to post the “why nots” and totally ruin my day. :slight_smile: