Bearing "shelf life"

I've read recently that NEW opened/unsealed engine bearings have a shelf life...even in a dry and CLEAN environment . What say ye? Never heard this before.



I guess some do have the date stamped on them after all.

Probably info provided by a study financed by the bearing companies.

I say BS.

makes about as much sense as an expiration date on rock salt.....

What could possibly change?

Airborne solvents, sunlight (not likely), ozone?

I was a millwright in a chemical plant, when it closed we had several replacement electric motors that we threw away. I asked about selling them and was told that they couldn't because the bearings go bad sitting on the shelf. I called B.S., then put them in the dumpster.

Date code is not only used for “shelf life”. Used for inventory control, recall, etc.

If it makes you feel any better I have several sets of Mopar bearings left over that are in their original cardboard packages. I have used bearings from this collection, that are from the late 60’s. Not a problem with any of them. Likely the only threat to a bearing in storage is moisture and that should be evident.

Acids in oil from use in an engine are likely more harsh than anything a bearing would see in storage.

Greased and in their original package? Their "shelf life" is longer than you will be alive, so don't worry about it.

If you ever tried to use rock salt from last year you will find it's a large block of salt now. I would suppose it depends on what the bearing surfaces are made of. It's possible the surfaces could start to form corrosion/rust but i think you would be able to see that. I remember years ago when TRW made bearings they where individually sealed and placed in a cardboard holder so they couldn't rub against each other. Ever look how Mahle bearings are packaged?

If you're so curious, why not ask the manufacturer !

I think it’s about metal migration….tin/lead alloys tend to migrate over time with copper and bronze and change properties.

Ever heard of "tin whiskers"?
This is a phenomenon in which, under special circumstances, tin surfaces develop tiny branches (like a crystal) that grow outward and short out printed circuit boards.
Does it only happen with current flow? I don't know.

Current flow can occur with dissimilar metals.

I will pay the shipping to take those unused "old" bearings off your hands.
Don't put them in the landfill ...

Same. I have a bunch too from early 70's. Just seeing if anyone else heard this before

Rant on shelf-life! When I was in the military quality assurance always harped shelf-life importance. For example an unopened tube of RTV that was expiring in 30 days would be sent to scrap. But if a mechanic used it on a jet engine that day it could fly for years with no problem.

If the new bearings, rings, pistons and any other motor hard part look good and measure correctly I will run them

x2. That's how thermocouples work, known dissimilar metals generate a small voltage and you can measure temperature if you know which metals are being used.

I bought two sets of Clevite 77 rod bearings for my 340 almost twenty years ago when I built it. If I ever put it back together, I'll use the spare set that's been sitting in my basement on a shelf all this time.