Piston ring seating; what does it mean

[stevenelle]

Another rebuild question. What does it mean when someone says that the rings need to be properly seated. Is this something that occurs after the first several sessions of running? How does one know if they are or are not seated. Any advice appreciated.

[grey beard]

When a new or remanufactured engine is assembled, what may look like polished parts to the naked eye are in reality quite rough under fine magnificatioin. This minor roughness is found on all machined engine parts - rings, pistons, bearings and journals. The first few times an engine is run, these parts are forced o work together for the first time. Each part that contacts another - rings in their lands on the pistons, piston skirts in their respective bores, etc., must actually "wear in" to the point where they will fit nicely and live a long and happy life in the presence of sufficient lubricant.

This is why tolerances are so very critical when engines are assembled, for these parts must "break in" during the first few minutes or hours of engine operation. If tolerances are far out of spec, this may never happen. This is also another reason why it is important to get the "break-in" oil out of the engine after the first few hundred miles, for it will likely have an unusual amount of metal in suspension in it.

Elsewhere on this forum someone asked about why their new engine was tight when turned over by hand. Each piston that is installed with new, highly sprung rings,, will add drag to the engine assembly. Once all are installed this drag can be significant. After the cam and timing components are installed, still more drag is noticeable, not to mention the paracitic loads like oil pump, water pump, generator, etc. Once the engine has run a few hours, this drag will lessen considerably. Once all these engine parts are micro polished against one another, the engine is said to be "broken in."

This is a long answer to your short question. Hope it is helpful. LOL

[knighthawk]

just courious, do you have a preferred od suggested break -in proceedure for now engines ?

[grey beard]

Jury's still out on that one, but it's a good question. I have heard two basic theories. The first is to take it real easy the first 500 miles and not to lug or overspeed it in any way during that time. In oher words, baby it while it is breaking in. I can even remember back in 1954, when Dad bought a new Chevvy that had a sticker pasted to the spedometer face telling you prettgy much what I have already said.

The second theory is only local wisdom, and I of course have never partaken of this forbidden fruit myself. Goes like this . . . Drill the livin' crap out of it from day one. Change the oil pretty soon after you start driving it, but drive it just like you want it to run in its real life, after it is well and truly boken in., You want a "hole shot" race car, then pull lotsa' hole shots. You wanna' take grandma to church, then drive like that. In other words, break it in exactly the same way you expect it to serve your needs.

On this same subject, I have perxonally never understood why new car makers do NOT recommend a first oil change after the first few hundred miles - unless they figger it's a good way o sell more cars., For my money, that first batch of "break in" oil needs to come out of there right away. Go figure . . . . . JMHO:) :)

[Big50Dodge]

On this same subject, I have perxonally never understood why new car makers do NOT recommend a first oil change after the first few hundred miles - unless they figger it's a good way o sell more cars., For my money, that first batch of "break in" oil needs to come out of there right away. Go figure . . . . . JMHO:) :)

Not much input on the break-in question, but I agree 100% with running the original oil short. I change the oil in my (new) vehicles after 1K miles. FWIW I change the oils on any used vehicle as soon as I get it home.

[Merle Coggins]

From what I've been told be various manufacturers, todays manufacturing process have such fine machining and cleaning process that a "break in" isn't necessary.

In my opinion, do what's comfortable for you