Yes, but the plastic pipe (the hot one running to the radiator, not the
cooler one returning from it) is subjected to higher extremes of
temperature and much more often than the sheet metal of the van. So,
while it may have a smaller coefficient of expansion, it suffers from
a much more extreme application of it. Every time you start the car and
run it to temperature on a 30 degree day, the hot pipe goes through a
temperature change of over 170 degrees. The rest of the car (minus
engine, brake, etc.) only experience about a 50 degree difference.

And I don't know about rubber expanding when cold. Every time I need to
force a resistant hose over a fitting I end up submersing the tubing
end in boiling water!

Jim

On Nov 20, 2005, at 5:00 AM, Daniel L. Katz wrote:

> wait a minute!! when it's cold the whole van shrinks, but the plastic
> pipe
> shrinks less in proportion because plastic has a smaller coefficient of
> expansion than metal, and rubber, of course, expands when cold.
>
> dan
>
> On Sat, 19 Nov 2005 17:19:52 -0600, Jim Felder <felder@KNOLOGY.NET>
> wrote:
>
>> Has anyone had this happen?
>>
>> For the second winter in a row, my 90 carat with plastic pipes
>> developed a drip where the rubber radiator hose connects to the long
>> plastic pipe at a connection visible just aft of the spare tire tray
>> but above the tire.
>>
>> And for the second year in a row, I can see exposed white plastic
>> where
>> the pipe has been pulled out a bit, about a quarter inch or a bit
>> more,
>> from where it normally fits into the rubber hose. Both times I have
>> loosened the connection, slid the hose back to its previous position
>> on
>> the pipe, and tightened the clamp again with nary a drip till cold
>> weather strikes.
>>
>> Obviously, there is some amount--looks like a quarter inch--of
>> contraction in the pipe in cold weather. It seems though that rather
>> than pulling out of the rubber hose, the pipe would simply move the
>> rubber hose, which I am sure was meant to compensate for the
>> temperature-caused movement of the long plastic pipe.
>>
>> Anyway, it's probably fixed at least until next year. I was wondering
>> if it was a common phenomenon.
>>
>> Jim
>