On 02/10/2017 11:15, Dave Plowman (News) wrote:
In article ,
Bill wrote:
I have always wondered whether this is a standard get-rid-of-him phrase
taught as part of the Car Mechanics PhD (Hons) course, or whether alloy
does actually start to leak.

Just the usual meja ********. If alloy really did go porous, your engine
would soon be scrap. Given pistons are made of alloy and have been for
many a year as is much else on a modern engine. And the pressure inside a
cylinder is far higher than in a tyre.

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...

If a steel wheel is rusty where the tyre meets it, that will leak too.


Agree there.

Andy