At 10:54 AM 22/09/98 EDT, you wrote:
>In a message dated 98-09-22 10:48:58 EDT, joe@GREENCASTLE.DYN.ML.ORG writes:
>
><< I was talking to a auto parts shops owner in my local area and he told me
> that the reason why my heads on my vanagon are developing small cracks,
> to cause small coolant leaks, may be due to the storage and backflow of
> heat from the cat? He suggested drilling a hole through the cat, through
> the hcomb about an inch in diameter. I am willing to try this if it will
> prolong the life of the heads. Is this an okay procedure to do? Any
> responses appreciated!
>  >>
>
That's a new theory. I do not see how the cat can affect the cracks in the
heads unless it is severely plugged. But even then you lower your energy
output which in turn decreases temperatures. The cat is there for
environmental purposes and it is up to your conscience to use it or not. In
addition of course you need the appropriate reading of the oxygen sensor to
give feedback to the computer for proper mixture. By the way cats are
mandatory in Europe.

Cracks are most likely to occur through heat changes and vibration. If you
drive short distances a lot then you put the engine through the stresses of
heat changes. Also if your fuel mixture is not correct you can affect the
heat in the heads. In addition check the mounting and bracing of your
exhaust pipes. A missing brace can cause vibration at the head and create
cracks.

Bj�rn Ratjen

Mill Bay, B.C. 

1987 Syncro Est Alia (self camperized)
1995 Passat TD
(1982 Vanagon Diesel)
1979 VW Bus (self- camperized)