To Oil or Not?...when installing new pistons?

[Johnny]

Been told a few things...whats right?
Some say oil the cylinder well before adding a new piston/new rings.
Some say just the skit of the piston.
I even saw a guy dip his piston in a pan of oil before installing it.
If using oil...regular oil or light stuff like WD40?

[OmniLuvr]

i always rub a thin layer of oil on the cyl walls with a clean paper towel (then check the towel to make sure its clean of any machining debris), my friend always dips his pistons, i feel as if the dip method makes more of a mess than necessary especially if you drip oil on gasket surface or in cooling passages. i think wd-40 is to thin, and will flash burn away on start-up, or run into oil pan before start-up. After i install pistons i also squirt a little oil around the top ring land to ensure a little oil up there on start-up. i also have a friend who uses atf and says it aids in break in, but not sure if i believe his claim or not...

[A.J.]

While holding the rod and piston on its side, I pour oil over the rings and catch it in a pan. I usually use less than a 1/2 a quart for 4 pistons. I think more is needed than just putting a thin layer on the cylinder walls.

[Ondonti]

Do you have people giving you advice who also plan on building the next motor for you for $ after you give up? Possibly some of that is bad advice from the old days of super rough cylinder hone finishes where you had to really knock down some high spots. Some modern rings require very fine hones that are nearly broken in when you first start up.

You can wipe some oil on them and the cylinders, and then pour a little oil into the cylinder too after (less messy) but I would take cleaning extra stuff off the deck anyday. Cutting corners to save negligiable time over something that is serious is something we should all get away from no matter the endeavor. Paper towels leave stuff behind but I don't see it hurting much. I always did. You can afford a higher quality wiper. Even medical gauze like the aerospace industry uses. We should all probably use more of that. Low lint & low price. Use the good stuff on the deck when you are cleaning it up. If you get a little solvent down the cylinder I wouldn't worry.

[going4speed]

I use atf as believe it's good for break-in.

The whole dipping pistons is a bad idea I think. It leaves all that trapped oil in the ring grooves so when the engine gets up to temp that oil will start to coke.
The way I see it is you have three rings. How is the oil going to get past the upper and lower ring set? it's sort of trapped there really.
When I install pistons I wipe the piston down with atf, install, then add a small amount of atf around the top of the piston.

[mopar-tech]

It leaves all that trapped oil in the ring grooves so when the engine gets up to temp that oil will start to coke.


Nope, that oil drains out in nothing flat.

Don't believe me? Stick a piston down in the bore and pour some oil over the top and let it sit for a bit. It will be drained out past the rings and bore in a few hours at best.

I have done them from dipping, to hand oiling to dry. They all work pretty good and can't say I have seen any ill effects.

Crate motors are effectively dry after sitting a few days or weeks, what the difference?

The last several dozen motors I have done go in with everything spotlessly dry (white glove literately) and then I'll pour motor oil in the bores to lubricate the rings. Usually I'll fire up a motor inside of a day or two after building. Always a very good ring seal.

Gary

[Johnny]

This is stuff I heard over the years, most many years ago.
And I see here many other opinions! :)



Been told a few things...whats right?
Some say oil the cylinder well before adding a new piston/new rings.
Some say just the skit of the piston.
I even saw a guy dip his piston in a pan of oil before installing it.
If using oil...regular oil or light stuff like WD40?

[iTurbo]

So far I've built '91 TIII and an '85 TI engines from scratch and I've dipped the pistons in a jug of SAE 30 oil and let the excess drip out. I do it that way to ensure the pin has oil all around it. I also wipe down the cylinder walls with SAE 30 oil just enough to wet them before installing the piston/rod.

Both motors are doing great and no problems with break-in.

[mopar-tech]

So far I've built '91 TIII and an '85 TI engines from scratch and I've dipped the pistons in a jug of SAE 30 oil and let the excess drip out. I do it that way to ensure the pin has oil all around it.

Thanks for mention that, I oil the pins by rotating on a stand and adding some oil from the backside.

Only good if you have a stand of course but no problems yet.

[thedon809]

I used assembly lube on the pins, all bearings and the I shaft gears. I just wipe the cylinders with whatever oil I have laying around and wipe the piston with oil.

[supercrackerbox]

Once I'm satisfied that the block is clean, I've always poured some oil in my hand and smeared it all over the bore, piston and rings, and the ring compressor. Assembly lube on all bearings/journals, and oil seals. I haven't had an engine fail on me yet.

But I've never pushed one that hard yet . . .

[going4speed]

Good to know that oil drains out. I was told that by a boat racer that built motors too. Another old wives tail I guess.


Nope, that oil drains out in nothing flat.

Don't believe me? Stick a piston down in the bore and pour some oil over the top and let it sit for a bit. It will be drained out past the rings and bore in a few hours at best.

I have done them from dipping, to hand oiling to dry. They all work pretty good and can't say I have seen any ill effects.

Crate motors are effectively dry after sitting a few days or weeks, what the difference?

The last several dozen motors I have done go in with everything spotlessly dry (white glove literately) and then I'll pour motor oil in the bores to lubricate the rings. Usually I'll fire up a motor inside of a day or two after building. Always a very good ring seal.

Gary

[Ondonti]

Good to know that oil drains out. I was told that by a boat racer that built motors too. Another old wives tail I guess.

Not sure where they get these ideas. Even the 1st ring has to scrape a little oil. Its not like the ignition in the cylinder instantly scortches oil and the 2nd rings deal with a lot of oil.. The crosshatching in your cylinder walls constantly have oil in them and that rides up into the top of the bore and is very exposed during the combustion stroke.

Gummed/coked up rings happen when you have old oil that lets its internal polymers break down and deposite in hot places. Fail HARD to do an oil change one time and you could gum up the rings. Mostly it just happens over time. Pulled apart engines where the oil rings were seized and the 2nd and 1st were nearly seized.
I am fairly certain the laziest rebuild of all could be dipping your pistons in Chem B and as long as you have a cross hatch, throwing it all back together after the rings/lands are perfectly clean. I have had to drill out oil return passages that were so coked with oil that they did not come clean with chemicals. I actually oversize these holes to help prevent them clogging.

[iTurbo]

Do you mean Berryman's Chem Dip? I bought a gallon can of that stuff to wash out the insides of intercoolers and just recently used it to clean up some 2.2L turbo pistons. Let them soak in the can for a couple days and all the carbon just wiped right off. I was amazed at how well it worked but will look closely at the oil drains.

[Ondonti]

Do you mean Berryman's Chem Dip? I bought a gallon can of that stuff to wash out the insides of intercoolers and just recently used it to clean up some 2.2L turbo pistons. Let them soak in the can for a couple days and all the carbon just wiped right off. I was amazed at how well it worked but will look closely at the oil drains.

Yeah I never knew about it until the last rebuild I did. Way easier. Me being a cheapo I didn't want to dirty it all so I just used a bit in another container. See if you have a drain near the pin too.

Unless there is a lot of physical damage/wear, often it seems like most of the improvement on a rebuild is that your rings are no longer gummed up. Cars like ours often go through terrible owners who don't change oil. I have always seen that 3.0's in mitsubishis are a lot cleaner inside than 3.0's inside mopars by a huge margin.

[Vigo]

Unless there is a lot of physical damage/wear, often it seems like most of the improvement on a rebuild is that your rings are no longer gummed up.

That correlates with my experience. It seems like most of the bearing/shaft damage i see is from particles embedded which has nothing to do with what people think of as 'normal' wear. Most cylinder damage i've ever seen is from engines sitting in one place with condensate or 'coolant' in the cylinders. And most piston damage i've ever seen is from.. detonation. :p

Engines don't really fail without doing SOMETHING wrong with/to them whether it's maintenance or tune related. After everything ive seen working on cars for the past 15 years i really think 'mileage' is an almost useless yardstick to go by when assessing 'wear' or the assumption thereof.

Personally, i own so many cars and change cars so frequently, i dont have time to put many miles on any one of them and none of them are worth a whole hell of a lot, so if i build an engine in such a way that the engine will last 50,000 less miles than the 450,000 it would do if everything is perfect.... it literally makes NO difference to me in my use case. If i did not oil pistons before running the engine it would make NO noticeable difference in the small amount of miles i would ever put on that car. But it's always a good idea to do things 'right' just for the sake of doing things 'right' as long as 'right' is something you can actually determine with a justifiably small amount of effort. ;)

[thedon809]

High mileage to me just means that there were more opportunities for people to mess something up. Not that the vehicle couldn't last that long. That's what keeps me away from high mileage, multiple owner cars.