[v8hed]

UPDATE...

Dropped the pan and pulled the pump.

Turned the pump shaft with it off the motor while it still had some oil in it and it felt horrible... not smooth at all and turning in really jerky steps. Emptied the oil out and now it feels smooth again when I just spin the shaft with my fingers.

I pulled the pump cover and inspected the gears... there's no damage, but I can see shiny and dull patches on each gear where they've been meshing. The black idler gear has some of the black coating partially worn away from this. Also, the gears have worn a few shiny patches on the inside of the housing, but nothing you can feel with your finger.

Does this all sound normal?

It's amazing how much difference there is in the smoothness of the pump between it being empty and it being full of oil.... perfectly smooth when empty and notchy as hell when there's oil in there.

At least this hasn't been a complete waste of time, as I discovered the front and rear seals were weeping, so I'll replace the gasket when I reassemble.

[larrywalk]

It's not normal. Time to replace the pump.

[SSedan64]

X2^^, should be smooth.
A few Pump Mods you can do if interested:
http://www.chevytech.info/2c63.html

[v8hed]

UPDATE...

Spoke to Melling tech support and the guy there said some jerkiness in the shaft is normal. He said it was more common when using a heavier oil (like a 20w/50), but the Select series have CNC housings and run tighter clearances than the lower-end pumps. I explained to him the pump was building pressure fine with the prime tool and I had tried filling the old 10550 HV pump with oil and the shaft on that turns in jerky 'steps' when full of oil, too. He said he wouldn't worry about it and it all sounds reasonably normal.

So, there you go... it's normal for the pump to feel notchy when it's actually pumping oil. If you think about how the pump works, it makes sense... the meshing of the gears causes a vacuum and oil gets drawn into the voids created. As the gears mesh further, the oil gets squeezed out of the outlet and fresh oil gets pulled in to replace it. It's not a continuous flow arrangement, so the jerky movement would correlate to the way the pump works. BBC pumps have more gear teeth, so I bet they run smoother.

[v8hed]

Just another update on this...

I found this YouTube clip... listen to how noisy this brand new Melling pump sounds when the guy starts turning the drive shaft. You can imagine how notchy it feels when he's turning it, too...

http://www.youtube.com/watch?v=XKA42hlpyIY

[delawarebill]

i also have a HV pump. and i don't recall it making a noise when i primed the engine.. it did feel a pulse like, i'm thinking cause its a hv pump.. i also used an elect drill.. sbc engine.. don't recall the brand name of pump..