Changing anit-freeze in a C5

[Art B.]

Does anyone know what the outcome might be if you did not follow the GM instructions for changing anti-freeze in a 2003 Z06? The GM service manual says that failure to empty the radiator, fill the surge tank, replace the pressure cap and run the car at 2000 to 2500 RPM until warm can result in "serious damage". While following this procedure the surge tank was completely emptied into the engine and while I assume this is normal I am curious as to what damage might be caused by not getting coolant into the system as long as you continue to top off the tank as more coolant is drawn into the system. I know on my C4 there is a bleeder valve near the top of the engine that you open to release any trapped air but it appears there is no such procedure on the Z06. Anyone know if I need to be concerned about the procedure I followed? Thanks.

[Tom H.]

Re: Changing anit-freeze in a C5

I can't see any serious damage to be caused as long as the coolant level is maintained. I'd say the serious damage warning is precautionary.

[Duke W.]

Re: Changing anit-freeze in a C5

I'm not aware that modern Corvette coolant changes are any different than vintage.

When you initially fill the system, it's tough for the liquid to fill the block because with the thermostat closed, air cannot quickly escape. That's why some engines have a bleed port near the thermostat housing.

First, fill the overflow tank to the normal hot or cold level, then fill the system through the cap opening on the pressurized supply tank or radiator. When no more can be added start the engine, and when the thermostat opens and the level in the pressurized supply tank/radiator drops, add until it is at the proper level.

Running the engine with insufficient coolant can cause overheating and alumiunum engines are much less tolerant of overheating than cast iron. Also, GM claims that the sludge problems with Dexcool are a result of running with insufficient coolant for extended periods, so the system level needs to be maintained.

After the initial start up and cool-down cycle the engine may draw coolant from the overflow tank, so you want to check coolant levels for the next few cycles and add as necessary until the level stabilizes.

On models with automatic climate control systems. make sure the heater core circuit valve is open, which may require manually opening a pneumatically or mechanically operated valve, and when you first start up the engine, place the the system on maximum heating.

On engines without auto climate control, place the heater control on full hot prior to draining and leave it their for startup.

Duke