On the left is the Series 1 water pump, on the right the Series 2. Both are AC Delco.
I just happened to have a new AC Delco Series 1 laying around when we did Matt's cam swap a couple years ago at my place. We did the comparison at that time, found them to be identical EXCEPT the Series 2 pulley doesn't have a hole in the middle, and won't mount to the Series 1 pump. Solution? Dig out a spare S1 pulley from my buckets 'o parts, and the problem is solved.
The Series 1 AC Delco water pump impellers are a far more efficient design (cast, curved blades) than the Series 2 stamped impeller, and is less prone to cavitation. It will move more water smoothly at higher rpm's than the S2. This is especially important on cars with raised shift points, although the few seconds of cavitation may not have much of an effect. Even the curved profile of the casting helps with flow. It's a gradual lift towards the shaft when compared to the S2 pump.
It's a direct bolt-on, and uses the same gasket, as long as you use the S1 pulley (wrecker, new, cheap).
Other than that, I prefer not to use plastic gaskets for these, if the new one comes that way. I prefer the black paper with red stripes. It's worth getting the right gasket before starting.
willwren wrote:The pump we installed on myfirstbonnie's 2k was an AC Delco pump. I got it from either Rock Auto or NAPA (I usually keep a spare on hand for the two cars due to the low cost). 30 something bucks. You MUST use the S1 pulley to make this work, gaskets are interchangeable between them. The S2 water pump pulley is the same diameter, but has a full crown face that will not bolt up to the S1 pump. Rock Auto used to have the pulley too, but I don't see it any more. Wrecker or any local dealer should. It should have a HOLE in the middle for the spindle of the pump to come through, not a full face-crown like the S2.
The AC Delco pump SHOULD be the right one on Rock Auto, but I see two. I doubt I still have the old box to check. Keep in mind that even if the pic on Rock Auto has cast impellers, if it's a rebuild, the core may not have. NAPA is your best bet. If they don't have one (not likely) have them order it, and check it before you leave the store.
myfirstbonnie wrote:As John said, you need a series 1 water pump with the cast impeller and a series 1 waterpump pulley. I am seeing about a 10 degree difference with this pump, compared to the series 2 pump with the following set up:180 degree t-stat and the fans are programed to run all the time.
