I have a 1994 Dodge Ram 1500 5.9. My water pump started leaking and when i replace the gasket, i was going to add an under drive pulley, problem is i don't know if i have a four bolt pulley or the six bolt pulley. It also has the stock water pump. Will somebody please shed some light on me so that i can get the correct one. Thanks Much Appreciated!

 

Are they talking about the water pump pulley? Or the pulley on the Harmonic Damper? My water pump pulley is pressed onto the pump shaft.....

 

On the early models, Ma Mopar used bolt on water pump pulleys. And the only one they used was a 4 bolt. They figured out it was cheaper to press on the water pump pulley around 1996.

If you have the original water pump, go ahead and change it. I'm also pretty sure that nobody makes an underdrive water pump pulley. And it wouldnt be a good idea to underdrive the water pump anyway.

 

Putting a smaller crank pulley on there will have the affect of running the pump slower. Not sure that it really matters though, it moves a fair volume of water in any event. Some of the sets come with smaller alt, and W/P pulleys as well, to keep those running at 'stock' speeds.