radiator flush and fluid change

**Vinny** · 10-30-09, 12:53 PM

Hi Got a 66 327.300 no air. I would like to change the antifreeze and flush the system. can you recommend a good flush agent and some guidelines for doing this procedure? also is a 50/50 solution such as prestone ok? thanks, vinny

**JohnZ** · 10-31-09, 02:25 PM

Originally Posted by Vinny

Hi Got a 66 327.300 no air. I would like to change the antifreeze and flush the system. can you recommend a good flush agent and some guidelines for doing this procedure? also is a 50/50 solution such as prestone ok? thanks, vinny

Most auto parts stores have the Prestone flush kit, which includes a tee to place in a heater hose and instructions. Be sure and remove the lower block drain plug on each side (just above the pan rail) - those are the only drain points for the cylinder water jackets. Use a 6-point socket so you don't round off the hex on the plug.

A 50-50 mix of the good old "green stuff" will work just fine; so will newer coolant with the Zerex G0-5 HOAT formulation. DO NOT use "Dexcool".

**Vinny** · 10-31-09, 04:14 PM

JohnZ, Thank you for the reply! vinny

**paul robb** · 11-01-09, 08:19 AM

A 50-50 mix of the good old "green stuff" will work just fine; so will newer coolant with the Zerex G0-5 HOAT formulation. DO NOT use "Dexcool".

[/QUOTE]

Why not dexcool...

**JohnZ** · 11-01-09, 06:05 PM

Originally Posted by paul robb

A 50-50 mix of the good old "green stuff" will work just fine; so will newer coolant with the Zerex G0-5 HOAT formulation. DO NOT use "Dexcool".

Why not dexcool...[/QUOTE]

Because the Dexcool formulation, designed for plastic/aluminum cooling system components, can leach lead out of soldered joints, weakening them (not good for copper/brass radiators and heater cores), and it's designed for fully-sealed cooling systems; air in the system forms sludge with Dexcool that can plug cooling passages.

**paul robb** · 11-02-09, 08:37 AM

Thank you mr. John Z. I'm still learning something NEW every day.....

**bigbear** · 11-04-09, 03:09 PM

I just read the installation instructions for AFR heads. It says to use distilled water as coolant. Since they're manufacturing aluminum heads, I'm thinking this is what I should be doing because of the Harrison aluminum radiator. The old helm manual doesn't make any mention of it. That said, it does make some sense. Given that water is a poor conductor of electricity, and that disolved minerals increase it, galvanic reaction (corrosion) would be more likely to occur with tap water. Additionally, living in Tucson for several years made me aware of Water Wetter, made by redline. Besides being a corrosion inhibitor, it helps with coolant temperature. Hot spots in the engine can create localized boiling, inhibiting the coolant's abilitly to carry this heat away. It helped noticably, and we all know how temps can soar in the summer in traffic.

**JohnZ** · 11-06-09, 03:25 PM

Originally Posted by bigbear

I just read the installation instructions for AFR heads. It says to use distilled water as coolant. Since they're manufacturing aluminum heads, I'm thinking this is what I should be doing because of the Harrison aluminum radiator. The old helm manual doesn't make any mention of it. That said, it does make some sense. Given that water is a poor conductor of electricity, and that disolved minerals increase it, galvanic reaction (corrosion) would be more likely to occur with tap water. Additionally, living in Tucson for several years made me aware of Water Wetter, made by redline. Besides being a corrosion inhibitor, it helps with coolant temperature. Hot spots in the engine can create localized boiling, inhibiting the coolant's abilitly to carry this heat away. It helped noticably, and we all know how temps can soar in the summer in traffic.

Any cooling system with aluminum components should use distilled water as half of the 50-50 anti-freeze solution (which is what AFR means in their instructions); you'll find that recommendation in the owner's manual of any modern car as well.

"Water-Wetter" is primarily a surfactant, to minimize nucleate boiling in hot-spots (which creates steam, which is a lousy heat conductor), and is designed to be used when 100% water is the coolant, as it says on the label, such as on road race tracks where anti-freeze is prohibited as a coolant. It's essentially ineffective when added to a 50-50 anti-freeze solution, as all anti-freezes already have a solid dose of surfactants in their additive package.

**bigbear** · 11-06-09, 05:14 PM

It's essentially ineffective when added to a 50-50 anti-freeze solution, as all anti-freezes already have a solid dose of surfactants in their additive package.

[/QUOTE]
Bingo JohnZ! I wondered about that, and there's the answer. I've been really enjoying your posts, and just can't tell you how much it means to be able to read about some of the "behind the scenes", engineering and development background you have shared. It provides such a great enlightenment in understanding a lot of the reasoning and details on a subject we all love. I thank you very much for taking the time you have, to post in this forum