Update: Water Pump Interchange

As discussed in an earlier posting, we needed to replace the water pump on our 1038, and chose to use an AC Delco 252-611 as a replacement. Once the water pump arrived, we first inspected the external housing to determine that it was dimensionally the same as the damaged pump, and found that it was virtually identical to 23500085.

Second, as discussed in the earlier posting, we needed to confirm that the rotation of the pump was correct. (V-belt applications use a rotor that rotates in the same direction as the engine, while serpentine belt drives require an impeller designed to work in the opposite direction).

6.5 NA Original Water Pump P/N 23500085 (v-belt application)

Upon visual confirmation, the impeller vanes are the same.

Replacement Water Pump AC Delco 252-611 (v-belt application)

After confirming the AC Delco 252-611 was a proper replacement, we painted the water pump with a glossy engine enamel to match the original pump. In painting a water pump be sure to not paint the face where the pulley mounts, the bearing (as paint can damage the seal), the ports where the fittings go (to ensure proper sealing), and the area where the lower radiator hose mounts to the pump.

Note masking to prevent paint on areas that should not be painted. After removing the masking tape, we were ready to install the pump.

As a note, we installed all bolts holding the timing gear cover and the water pump to the timing gear cover with blue Loctite. As there are seven bolts holding the water pump installed from the inside of the timing gear cover, it is extremely important to use Loctite and torque to specifications. Should one of these bolts loosen or fall out, they fall directly into the timing gears.

Additionally, there are five bolts installed from the outside that are tapped into the water jacket. It is important to re-apply sealant on these threads to ensure engine coolant does not leak on the threads. We used Rectorseal #5, but other products will also suffice.

UPDATE:  As we reviewed the drop-shipping invoice, the water pump is billed out as a GM 88926125. This application shows at least for civilian 1990 6.2L, and also corresponds with Airtex AW5008 indicated in a prior post.