Installing a gerotor oil pump might not be the most natural thing in the world for some of you who grew up with the more “traditional” spur-type pumps found in small-blocks. However, if you are building an LS or one of Ford’s line of Modular motors, the oil pumps are a different animal, altogether.
That said, recently Melling has received a rash of pump returns — specifically on the Mod motors — where incorrect installation has led to the destruction of the pump housings. Melling’s Technical Director, Cale Risinger, walks through the process of properly installing one of these pumps without causing damage.
“We’ve gotten some pumps back recently, either through returns or warranty, with either the flange of the pump broken right off, or a fracture running through it,” Risinger explains. “What we’ve seen is, the pump isn’t being fully installed onto the mounting surface. The sacrificial nodes are catching on the crankshaft flange, and then being pulled down with the bolts.”
With the pump “bottomed out” on a false shoulder prior to being tightened down, even at the recommended torque, the casting snaps, since the pump isn’t actually up against the block. In order to ensure that the pump is fully seated prior to tightening the bolts, Risinger walks us through the complete installation process.
After adding some oil into the pump and rotating the pump a bit, the trick is to line up the flats of the crankshaft with the drive flats on the inside of the gerotor of the pump. “By getting those to a point where you know they will line up with the flats on the crank makes the process easier,” Risinger says. Once the pump is fully engaged, you’ll be able to see part of the crankshaft’s step protruding from the front of the pump and there will be no lateral wobble of the pump.
The key to not having the issue is to ensure that the pump is properly seated before tightening the oil pump mounting bolts to their final torque of 89 lb-in. It’s a simple process as long as you are paying attention and don’t get caught up on the shoulder of the crankshaft.