Somebody posted this in June of last year:
Assuming all else is in order, and they really are putting new ones in,
this sounds like the same problem that's shown up on some Fords. Due to
poor grounds there is some electricity actually flowing thru the coolant
and it causes electrolysis, which corrodes the hell out of the heater
core. You can check for it by measuring the voltage reading (with the
engine running) between coolant and ground. With the rad cap off, stick
one voltmeter probe into the coolant about an inch and hook the other
probe to battery negative. If you get more then about 0.33 volts you may
have an electrolysis problem. Do a search on google and you'll probably
find lots of info.
On Mon, 2 Jun 2003 16:52:35 -0500, "Defiant"
Hi all I seem to have a problem with my 95 Chevy Silverado pickup that
is really getting out of hand and I need some advice or some help. In
the last 2 1/2 years I have had 4 heater cores replaced in this truck
and the last one went out Friday is there a problem with the Chevy
trucks or am I just having a string of bad cores.
On the last one the guy who installed it said the old one looked like it
had a burn mark in it does anyone have any info on this? Wednesday
morning I'm returning it to the same shop for another replacement core
under warranty but this time they are installing a GM core instead of a