Cavitation only happens when either your have a bad engine/frame ground and/or when your antifreeze has run out of additives that coat the metal(s) in the cooling system. Cavitation also happens around the cylinder and or combustion chamber in the head, because it results from small air bubbles that ALL cooling systems have in them. The small bubbles are in the system, laying against the metal and when ignition happens the walls of the cylinders/casting expand rapidly, causing the air bubble to smash into the cylinder and implode. Kind of like sandblasting with air bubbles. Water will not boil in "hot spots" in the engine as it is combined with the Ethylene glycol (AKA Antifreeze), which raises the boiling point of the water. The timing cover would be a location that would be the coolest of the entire cooling system as it is directly in line with the coolant coming of the cold side of the radiator. Most likely the erosion that plagues these covers is not due to poor coolant but from poor grounds. I've worked on heavy duty Diesel engines that have much more stringent coolant conditions than the small gasoline counterparts. We had troubles with Cat 3406 Diesel engines back in the early 90's chewing the backing plate from the water pump. Caterpillar in an attempt to cut engine weight had moved several former cast iron pieces to aluminum. The backing plate of the 3406 water pump could be compared to the timing cover of 260's and early 289's.
HD Truck manufacturers for years had grounded the large alternators directly to the bolts located around the water pump and or thermostat housing. The alternator bracket sandwiched around the water pump, so grounding to anything in the area would mean direct contact with the cooling system. What was found was the ground for the engine to frame was normally attached to the starter lug. The entire engine ground had to pass through the starter housing, and then onto the bellhousing and through to the engine block. That proved to be craptastic and the ground would often flow through the coolant into the radiator and seek a ground from there. The ground issue resulted in erosion to the pump spacer and thermostat housings. It would look like someone had dipped the parts in acid and left them there. It would damage the parts even with fresh coolant as the electrolysis would wipe out the additives shortly after filling with new coolant. We would test it by putting a volt-ohm meter lead in the top of the radiator, directly into the coolant and check for voltage with the engine running. Fixing it required removing the factory ground and running a new cable from the alternator down to the vehicle frame.
What attaches to our water pumps that have these front timing covers? Yep, Alternators and Generators.
