Cooling system flushing warnings

[deecee@exit109.com]

Be extra cautious when flushing and refilling the cooling system on these
cars. It happens about 5% of the time and I would hate it to happen to
you..  The problems use to be on the very early water cooled cars that
didn't have expansion tanks. If the coolant level fell to low in the
radiator the system became air bound. The addition of the expansion tank
helped.  Here is a short horror story that happened to me a few weeks ago.
My Boss decided to send out coupons offering a coolant system flush and
fill.  I was given a 1995 2.0 Golf for the coolant special. The down side
was the car was just driven to our shop and the customer was waiting . I
warned my Boss of the consequences of draining and filling a hot engine. It
didn't matter and I had to do it since the customer was waiting. I dropped
the coolant and added the flush and regular water. Since the engine was at
normal temperature as soon as the cold water hit the thermostat it send the
thermostat into cardiac arrest.and slammed it closed.  I didn't realize the
problem until I noticed Old Faithful blowing it's load of steam.  I spent
the next 3.5 hours waiting for the car to cool down enough for the
thermostat to unstick. I did everything to get all of the air out of the
system. After a total time spent of 4 hours I was able to get the cooling
fan to cycle. 
I told my Boss what had happened and reminded him of what I told him before
we started the repair. I was paid my complete time on the job and the
customer was only charged for what the special price was. She waited the
complete time. This was not the last I had seen of this car. Last week she
brought it back because the coolant light was on.  Bottom line was I had
caused the head gasket to blow out. I replaced the gasket under the
5/50,000 power train warranty.

My advice. Never perform a coolant flush on a hot engine. If you must boil
the water before pouring it in the expansion tank. My suggestion. On a cold
engine drop the coolant lines and drain out as much coolant as will drain.
Remove the top hose from the radiator and add the new coolant until it
begins to rise in the expansion tank. Run the car with the cap off until
the fan cycles. (A/C Off) The following morning check the coolant level
before starting the car. If any air remained the level will drop.


Don