If my pistons lose 0.1% of the gas on every stroke I won't notice. They are typically running about 25 power strokes a second. If my tyre lost
0.1% of its contents every 25th of a second I think I'd notice...
Agree there.
Andy
How about the cooling system often made of alloy these days. If that were porous, it wouldn't hold pressure.
The tubes of an alloy radiator are wrought and not cast. The process that makes the tubes compacts the alloy, distorts the crystal grain structure and removes (most) porosity.
Casting process can entrain gas and that results porosity. So cast blocks and heads can be porous but drawn tubes and rolled sheet won't be porous. In part the thicker walls of castings prevent porosity as all the holes have to line up and join up for it to leak.
Aero grade alloys for large cast structures (jet engine intercase) are vacuum melted to remove gas and vacuum cast. They can still suffer from strain induced porosity, where voids open up between the crystal grain. Unlike a crack that will go though a grain.
But loads of the rest of the engine, cast. Many engines these days have an alloy block and heads.
Can you see the corrosion if you take the tyre off. i.e. is it obvious to repair.
yes, but I would usually put detergent around the tyre first to confirm the leaking side/area.
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