Cooling system weirdness

[gforbess at attglobal.net (Gordon Forbess)]

On Mon, 6 Jun 2005 22:19:50 -0400, "Jim Ruffi"
<sciroccos@earthlink.net> wrote:

>The trip home was a definate test of a lot of my car's parts.  Luckily,
>nothing broke.  I had replaced some hoses, the metal coolant pipe, added the
>missing "bypass" hose and filled the system with red dexcool-compatible
>long-life coolant.  When I originally finished the changover, the water pump
>impeller-to-housing gasket leaked a little.  I was able to snug it a little
>and the dripping stopped, but it bugged me.
>
>David U. told me he had heard of a couple of other people who converted to
>that type of coolant and had leaks...
>
>About 2 hours after my return from Cincy, I went to move the car and found a
>tiny puddle below the car.  I checked the car and found a very tiny amount
>accumulated where the lower hose-to-waterpump connection and much more
>coolant leaking out of the seam of the expansion tank.  The PO had changed
>this tank at some point and it looked to be in otherwise good shape.
>
>I had the system filled to the "high" mark when it was cold and it was a bit
>above the mark when hot.  The car ran nice and cool in the 90 degree heat,
>with the gauge in the lower end all the way home.
>
>Maybe I overfilled the radiator?  Maybe the red coolant somehow creates a
>higher system pressure?  Maybe a defective cap, combined with too much
>coolant cause the tank fracture?  Maybe the red stuff is too "leaky" for my
>old car?  good thing I made it home ok.

I'm begriming to believe ANY work on a cooling system will result in a
few leaks that will need attention, no matter what coolant is used.
My thought is that (like water faucet supply lines in your house)
sediment tends to accumulate and self-seal small leaks over time.
Stir it up a bit by changing components or the coolant itself and
you'll get some drips here and there.

Your expansion tank could have just failed for no good reason, on its
own.  If it wasn't brand spanking new, you can't really trust it (or
the cap) was good.

I just replaced my expansion tank, cap and a couple of small hoses as
a preventative maintenance measure, stirred up some rust and decided
to flush and refill.  Had the same lower hose connection get a case of
the drippies after a week, but a half turn on the hose clamp was all
it needed. 

The important thing is what the temp gauge told you on the drive.  Buy
a new cap and tank, check the tightness of all your hose clamps, and
keep an eye on the coolant level for a while.  Worry if you see
coolant coming out the shaft seal on the water pump, puddling in the
interior, or showing up in the oil, but the leaks you've described are
relatively easily explained and cheaply fixed.  



Gordon
75 Scirocco/Drake 1.9 8V
http://pws.prserv.net/scirocco/scirocco.htm