Just completed my 200,000 mile timing belt change, changing the water pump and all the idler pulleys, the hydraulic tensioner, belts, etc.
I noticed a strange design . . . the replacement water pump pulley has equally-spaced teeth, to mate with the timing belt, around the entire circumference of the pulley. The original, Volvo pulley, however, skips a tooth every after every third tooth and, at one point, after every second tooth.
A very strange design, but apparently purposeful.
Any ideas as to why this design?
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