Well castings can be p porous, and normally they used to be Xrayed to show
this up, but I've not heard of it happening later without the start of these
issues being there to start with. Seems to be yet another cost cutting
method, but really how old are they?
brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Bill" wrote in message
...
I may be about to buy, from a scrapyard, a set of 5 replacement wheels for
the recently purchased car to get a spare wheel, proper sized tyres and
wheels that fit the wheel nuts.

In the past, I've often been told that the reason for a slow puncture was
that the alloy wheels had gone porous.
More recently, I've been told that the cylinder head on a certain vehicle
had gone porous and that was why it chuffed when cold.

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.

Does anyone know? Is there any sort of standard test, like wheel tapping,
that can detect this sort of rot?
--
Bill