ok so the pump didn't come with any studs where the pulley and fan go on.. that's fine.. I ordered stock studs from the local dealer.. I put the studs in tonight and go to put the pulley on and it doesn't fit.. studs are farther away from the center than the stock pump ones.. so I drilled out the pulley holes a little bigger.. that's fine it fits now and slides tight on to the center shaft.. now for the fan I had to drill it as well but the holes where already very close to the outside.. I ended up having to make a slot from the outside.. so now there's no metal on the outer part of each hole.. fan now fits on top of pulley.. is this ok? there's no way for the fan to come off as the fan basically fits in between the 4 studs and then I have washers with the nut on top to secure it...

 

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Sounds like you got the wrong pump. Mine fit perfectly.

 

There are only 2 bolt patterns on water pump pulleys. The larger one has been in use since the late 60s, and is the only one used on long pumps. I can't imagine how it could be wrong, unless you are using a non-stock fan, and your old WP had both patterns in its hub (many do).

But in any case, lots of fan clutches have slots like you describe, so what you did should be OK.

What combination of parts have you got?

 

I hope you're not using a "normal" pump in a serpentine belt "reverse rotation" water-pumped truck. The water pump will be spinning the wrong way!!!!!!!!!!!

 

the pump I used was #13123 which is suppose to be the one for serpentine.. the thing is before I put the studs in I tried the pulley and fan and they fit snug on to the center shaft but the 4 holes where the studs are where off by maybe 1/16 of an inch..

the pump itself isn't stamped with 13123 number.. it has EI-626 and XZ-G009 on it..

 

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