Coolant Overflow to Recovery Conversion
Many Mark III's are built with a Jaz Coolant Overflow Bottle. This bottle is required for track events to prevent coolant from overflowing onto the track. The proper use of this bottle is to open the petcock on the bottom of the bottle prior to any track event to make sure the bottle is empty and then to close the petcock. While on the track, if any coolant overflows, it will be captured in the bottle rather than onto the track.
The disadvantage of the overflow bottle, though minor, is that it leaves air in the cooling system where corrosion can form. Some prefer, for this reason, a recovery system is used so that the coolant overflowed will be recovered when the engine cools down. Converting the Jaz bottle to a recovery bottle is a simple conversion.
Remove the top fitting and grommet from the bottle. It just pulls out.
Remove the Grommet from the fitting
install a washer and a piece of 1/4" x 6" long vacuum hose onto the fitting
Push the fitting back into the Jaz bottle. The 1/4" vacuum hose replaces the original grommet sealing the fitting to the bottle.
With this conversion, the Check valve on the bottom of the bottle is retained so the bottle can be properly serviced for track events.
IMPORTANT NOTE: Neither the petcock or radiator cap should be opened before the engine has completely cooled when using a recovery system. If the petcock is opened, coolant may be drained that would otherwise have been recovered. If the radiator cap is removed, the vacuum in system that facilitates recovery will be lost and complete recovery will not occur. Neither of these conditions will degrade engine cooling, but will negate the advantage of a recovery system.