As mentioned in an earlier post, either the water pump was damaged during shipment of the powertrain, or we had damaged the water pump during the process of re-installing the body.
Sourcing a replacement water pump is not extremely difficult, as according to the TM, the replacement part for our 6.5 NA motor is the same as for the 6.2 (PUMP,COOLING SYSTEM 6.2 LITER AND 6.5 DETUNED). However, our book did not provide a NSN, only a p/n 23500085.
This p/n interchanges with a number of cross interchange parts:
- AIRTEX AW5008
- ASC WP-598
- ASC INDUSTRIES WP598
- GM 12514269
- GM 12534418
As well as many others. (See e.g., https://www.yoyopart.com/oem/11722356/gm-23500085.html#interchange)
Depending upon where you source your water pump, and what p/n you use as basis for your search, prices seem to range from $38.00 to $395.00. With a desire to be cost effective, we traced all interchange numbers down and determined two parts were acceptable for our purpose.
- AC Delco 252-611 ($38.37 Amazon (with coupon applied))
- GMB 74973 ($42.95 eBay)
Of Primary Concern is the rotation of the water pump. The water pumps used in the earlier V-belt drive operate in a different rotation than the later serpentine drive pumps. Ours is a V-belt drive meaning the water pump turns in the same direction as the crankshaft. Based on our research and purchaser comments, we purchased an AC Delco 252-611 from Amazon.
After discussing aftermarket pump reliability with Tim Grundman (owner of Big Dawg Diesel Worx, LLC), we would have felt equally comfortable with the GMB water pump, it was a combination of lower price and AC Delco being a direct GM part replacement that we chose the AC Delco pump.