C2 flush and fill time

[Randy S.]

What is the best way to flush and fill (with Zerex G05 thanks Duke) without removing engine drain plugs. I have a 66 small block with AC (heater shut off valve)

I searched archves and found a recommendation for a cold reverse flush followed by a couple of hot flushes but the cold flush won't work for me due to the AC heater shut off valve.

What about
1. drain radiator 2. hook garden hose to intake manifold fitting and reverse flush and just let motor idle until water coming out of disconnected heater hose and radiator petcock is clear. Vacuum will open the heater valve and there should be enough temp to open thermostat.

3 follow with a couple of hot flushes with distilled water
4 drain radiator and add 2 gal full strength Zerex G05

Any other suggestions

Randy

[Donald B.]

Re: C2 flush and fill time

I just did my '62 - you need to check the fluid capacity. Two gallons might not meet the 50% minimum recommended concentration level.

[Duke W.]

Re: C2 flush and fill time

Removing the block drains is preferable, but if they are frozen/rounded off, disconnect the heater core inlet hose at the inlet manifold after draining the radiator. With the engine cold and the radiator drain full open, flush the heater core circuit with potable water then flush the engine until the effluent is colorless and tastless and flush the heater circuit one more time. This will leave about a gallon of water in the block.

Install two gallons (2.5 for a BB) of Zerex G-05, and finish filling with distilled water.

A SB with heater is about 16 quarts and a BB 23 total capacity, so you should end up with about a 50/50 mix of glycol and water.

Duke

[Randy S.]

Re: C2 flush and fill time

Thanks Duke,
Wheh flushing the heater circuit I'll either Mighty Vac the heater shut off valve or idle to get the engine vacuum.

Randy

[Duke W.]

Re: C2 flush and fill time

Unless the cooling system is contaminated/dirty, I thinks it's best/easiest to cold flush. Assuming the system is basically clean, all you are trying to do is purge as much of the old antifreeze as possible, so use the Mighty Vac to hold the heater valve open.

Duke