sleeve "O" rings

good run Mitch ...they still don't get it

What I do get is that this post is less about O rings and more about business. You're upset with a vendor because you now think you made a bad buy decision before you researched an item. If you buy your groceries at store "x", buy bananas at $.69/lb, stop at store "Y" on the way home to get meat and find out this store has bananas for $.35/lb, do you go back to the first store and demand a refund because their bananas are twice as expensive as the second store?

Sounds good to me!! go for it!!

And the material in that .06 ring may last the first time you run the engine. O-rings for sleeves tend to not stand oil well, to the point that using an oil rather than an approved soap to lubricate them at assembly causes rapid deterioration. But they stand up to antifreeze, both types, heat and vibration. Rings that stand up to oil are used in hydraulics and aren't affected by being immersed in oil, different material that those for sleeves.

Gerald J.

mlpankey wrote: use dow corning 111 silicone grease on all o rings that are being assembled and have no deteriation of any material that o ring was produced by  . Its stands to reason that any chemical used on material that isnt chemical resistant to the chemical being applied to material causes deteriation.

Yup, I used to think that too, and did use silicone spray and grease on a lotof stuff:



Source: http://www.advantageengineparts.com/

Nowadays, I use exactly the same stuff as I did with my first sleeve job: "soapy water solution", otherwise known as Murphy's Oil Soap. Some fellas I know prefer Palmolive (they like to keep their hands silky smooth).

The other thing that matters and isn't mentioned in the quoted article, is "stiction".

Since whatever lube used is in a confined space, and not subjected to a lot of flow, it stays around in that location a long, long time.

And here's the deal - Silicone lubricates REALLY well. Which sounds good except: doing that allows the face of the seal to move against the bore it rests in - and that ain't good.

Every time that cylinder fires, and that piston moves up and down, there's a tendency for the sleeve to move too. Well, that head and gasket holds it in place pretty well - but not absolutely - there is still micro thousands of motion going on.

What the goal of the o-ring fitting properly is - that it fill the groove its fitted to, then have enough "stiction" to grab the outer bore.

What's left is that the o-ring material in the middle flexes - along the same line as holding a wad of sticky bread dough between your hands, then rolling it up and down - the outer bread dough sticks to your hands, and the dough in the middle has to move.

This way, the outside diameter of the o-ring isn't abraded away from that micro-motion of the sleeve in the bore.

A hydraulic cylinder goes up and down a few times a day. An actuator valve cycles a few times a day. The seal at a hydraulic fitting relies on static adjustable compression. But an engine at 1400 rpm (or 5000) man, that adds up really fast.




Edited by CJohnS MI - 02 Sep 2010 at 12:50pm