The Engine Guardian Water Pump Drive System (EGDS)

EGDS for Porsche 928 32 valve engine

Perfex Manufacturing, Inc.

EGDS was developed for the Porsche 928 32 valve engine because of the need to prevent catastrophic engine damage in the event of a water pump failure. The water pump is driven by the timing belt which also drives the camshafts. If the water pump shaft seized or became difficult to turn this would cause the timing belt to fail and in return cause extensive damage to the valve train by way of piston to valve contact.

The EGDS incorporates a separate large double row ball bearing to do the job of idler pulley in the valve train system, and couples that energy to spin the water pump shaft via a consumable coupler. The consumable coupler is engineered to shear itself from its drive sprocket at a load point less than the load point that would cause the timing belt to slip or stop.

The EGDS protects the valve train in case of pump failure and increases the life of the water pump shaft bearing immensely as it no longer has to withstand the load of the cam belt. The separation of linear side to side loads from the shaft to the larger bearing eliminates pulley and impeller migration which has been a ticking time bomb in these engine. The EGDS increases the life of the water pump as a result.

Above: A test unit is shown with the major EGDS components-

The EGDS includes a removable cover to allow inspection/ replacement of the coupler at anytime. The removable cover also allows the inspection of the water pump shaft and drive bearing play at service intervals. The EGDS impeller is drilled and pinned to the shaft as an added measure to assure no migration into the engine block.

New pumps that are chosen for modification are inspected and tested for casting and pump condition, as well as impeller clearance, bearing stiffness/noise and a torque test. These items are continuously monitored during the disassembly, machine operations and assembly of the pump to ensure consistent quality during the process. During assembly at Perfex Manufacturing, Inc. all operations are paint marked after completion to assure quality. A final inspection and torque test and the pump is packed with a focus on impeller and drive pulley protection.

Water Pumps for the 928 engine manufactured by PerfexMfg since January 2012 carry a limited warranty of three years (unlimited mileage) to the original purchaser.

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Perfex Manufacturing - 30 Commerce Drive, P.O. Box 1217, Danbury CT 06810

Phone: 203.739.0930 - Fax: 203.739.0949 - Email: