Adding aftermarket coolant recovery tank to 68-72 big block AC car

[Steve G.]

Re: Adding aftermarket coolant recovery tank to 68-72 big block AC car

Thanks for the input guys.

One clarification: I'm not doing this to fix an overheating problem; my LS5 runs fine. Coolant temp typically stays near the thermostat's setting of 180 degrees, but may drift closer to 200 in traffic with AC on. Certainly not a problem.

But a coolant recovery system has significant benefit: air is eliminated in the system (benefit: with a proper mix of clean coolant this eliminates virtually all corrosion; no aeration means more efficient cooling) and there's no loss of coolant (benefit: no mess on the ground; changes in coolant level due to a leak are more detectable; no discharge of toxic liquid to the environment).

I've owned a lot of pre-73 GM cars and found that adding a recovery system has helped maintain a clean, efficient cooling system with components that last longer. There's a reason GM adopted it for newer cars.

Anyway, I'm still interested in learning about any installations out there for these cars. With the limited space, it's more involved than with most cars.

Thanks again.

The coolant recovery system was used to deal with a specific situation. All systems must have provisions for expansion of the coolant. The simplest was air space in a tank above the core. The core was always completely full with additional liquid (ensuring it stayed full) and air space above it. The coolant expands and displaces the air. Over filled it pushes the excess out. When cooled, air returns. Finds it's level then operates as it should.

Cross flow rads with side tanks using that same system to provide the airspace would be using up valuable and expensive core space just to hold air. The tank can not simply sit on top because coolant would simply run across and bypass the core. So they had to come up with an alternate arrangement for cross flow rads.

One was to completely fill the rad, no air space, and let the coolant travel back and forth between the rad and the coolant recovery tank. Expansion pushes the coolant through the cap while maintaining system pressure, then allows it to draw back when the coolant cools and contracts.

The other way to keep the core full is to provide a remote tank within the pressurized system mounted above the height of the top of the rad. Now the rad stays completely full and you can have air space in the tank. This is how it is done on your car and most cars built today.

The little bid of additional coolant you would add to the system by eliminating the air space in the tank in favour of a coolant recovery system would be of no benefit. It's adding a second solution to a problem already dealth with.

Steve

[Michael W.]

Re: Adding aftermarket coolant recovery tank to 68-72 big block AC car

Mike------


All 1969-72 Corvettes with big block do not use a radiator with a filler on one of the side tanks and, thus, there are no fill marks on the side of the side tanks. Instead, they use an external supply tank like many small block cars. The configuration of the system being what it is, I doubt that there is any "headspace" in the radiator as long as the external supply tank has coolant in it.

The external supply tank should not be filled more than half way. If it is, the amount above half will be rather quickly purged out the overflow.

True enough. I was thinking of the cap on rad configuration rather than separate supply tank. This eliminates any air being in the rad and the idea of reduced corrosion as a supposed benefit.

[Jim H.]

Re: Adding aftermarket coolant recovery tank to 68-72 big block AC car

FWIW, Mark, I, too, considered adding a coolant recovery tank to my '66 427 when restoring it given the prevailing opinion that BBs run hot. PO had a Peps Boys unit installed and I intended to do something better and more high end. I was persuaded to delete it by some buddies of mime who said with all new cooling system components in my car after restoration the recovery tank would not be necessary. I've now driven some 1500 miles on multiple extended tours of 300-400 miles per day in the California heat and my '66 is running cool and w/o need of coolant recovery. I check the rad every time I go out, but so far zero problems.