Ford Flathead Water Pump History - Pumped Up

There's also another element common to all stock Flathead pumps: carbon seals. A spring assembly on the impeller side of the pump forces a carbon ring against a fixed plate. While the design effectively prevents coolant from forcing its way out of the water jacket, these seals cannot bear more than 4- or 7-psi coolant pressure, depending on the year. Coolant simply weeps past and eventually destroys the seals at pressures greater than those.

We feel it's important to disclose this original construction on the outset, as each one of the replacement pumps in this story employs a modified or outright different seal design to help them withstand greater working pressures. We'll expand upon this further in the story, but it helps to know immediately.

For a brief primer, consider the following: Passenger designates all Ford and Mercury passenger cars; Ford and Mercury designate designs specific to each marque; while Truck refers specifically to heavy trucks and Pickup, specifically to light trucks. Both can be either marque, as Ford of Canada badged many trucks Mercury and equipped them with namesake engines.

As mentioned earlier, this chart illustrates Ford's original pump configurations. Treat it as reference rather than gospel, as many exceptions to the rule exist due to midyear changes, stock on hand, and manufacturing facility.

Flathead JackEnter "Flathead" Jack Schafer. As a Flathead devotee, Jack is, by default, a bit of a curmudgeon. And as curmudgeons go, we begrudgingly admit he's frequently right. This is one of those cases. After working around the Flathead pumps' shortcomings, not the least of which includes the weak carbon seals and combination pitfalls, Jack did something seemingly impossible: He redesigned them. To top that, he had 'em cast in aluminum.