It was indeed a Honda Goldwing owner, a gentleman by the name of Carey, who first wrote to Motorcycle Consumer News (MCN) about his five successive water pump failures. In their request for more information, the magazine received hundreds of letters from other motorcycle owners. After six months of study, MCN published their findings in their August 1997 issue.
First, MCN found that 99% of the failures occurred after the OE coolant was replaced. Second, in 99% of the reported failures it was replaced with either Prestone or Zerex automotive anti-freeze. In less than 0.2% of the reported failures Pro Honda HP or another motorcycle-specific coolant was used. Writes MCN,
Conversations with chemical engineers at Dupont and Prestone revealed that their coolants contain microscopic silicate particles—like a very fine sand or ground glass—which are designed to 'scrub' rust and corrosion from the surfaces of radiators. Their experts claim that in all their testing these silicates have never damaged seals or O-rings in water pumps, but they also concede that no testing has ever been done with motorcycle water pumps.
It seems likely that the water pump failures on Gold Wings are being caused by the silicate particles in the automotive coolants.
In later issues, MCN maintained that silicate corrosion inhibitors in automotive coolants can damage the water pump seal of the Honda GL1500 Goldwing in particular, as well as other motorcycles in general.
Several automotive coolant manufacturers now offer anti-freeze that is labeled silicate-free, such as Prestone Extended Life 5/150 Antifreeze/Coolant.
