Hemi oil pump drive shaft failure

BAE Hemi with PSI mag drive, P&P dual stage oil pump, oil is 50 weight and warmed before starting, no oil in pan. I have been having trouble twisting and shearing the 3/8 hex drive for the pump. Not sure if its because there is no oil in pan and when it does pick up it may shock the pump and load up the shaft. This has happened 4 times now.
Hopefully there is an easy fix, please help.
Or I would like to know what are others are running, or even if its a multi stage belt drive dry pump.
Thanks guys

 

You could try checking the bypass piston/spring to make sure that it is not stuck in the closed position as it could then send the pressure to the moon right at the start and shear the drive before you even see pressure at the gage. Just a thought to check that it is operating freely.
Jeffj

 

Hi Guys,
Yes only on start up, I will have to check data for the cold pressure, hot is around 70-80 psi.
BAE 6 heads, 24 deg timing at idle.
I have two engines that it has happened to. This engine is fresh with new internals.
No filter into engine. only on return to tank. Filter is systems 1 and is in correct way.
Pump was stripped and checked during rebuild, bypass was free.
Thanks for your replies.
Joe

 

Im running system1 pump so im not familier to the P&P, But system 1 doesent have a bypass valve on the scavange pump, Do the P&P have that?

Otherwise it could be cold oil in the filter on the return line, wich filter element do you have? there is a lot of different microns from system 1, have you checked the bypass in the filter?

 

What are you torquing the pump to the engine bolt to? Is this a new problem or has it been ever since you started using this pump? I have seen the pump sections become too tight when it is bolted together and cause the shaft to break.

Try turning the pump with a speed handle when it is bolted to the engine and see if it turns freely.

 

There was no oil in the filter on start up, my filter does not have any bypasses in it. Have ran this filter for years so element is fine, not sure of the microns. Oil didn't even get to the filter so I think its definitely not that.
I have run KB and system 1 pumps and it never happened to these. Only with the P&P, The pump is still on the engine and mag drive out so I will check if its free tomorrow, The pump was not torqued, just done up tight.
Thanks Joe

 

Check the scavange hoses. Maybe one of them is collapsing.

 

First thing i would do is take the pump off and send it to RCD and have them check it for flatness or binding
possible pin coming out of the rotor/s
have them bless it
i have never seen a drive twist or shear unless the pump has crap in it to lock the rotors
second put a scavage filter between the pump and pan to catch the metal before it hits the pump
peterson makes a nice filter RBS has some cone filters that go into the scavage line too
got to stop the junk from getting into the pump

 

I have oil pump shafts for sale. some of the p&p pump you have to check the clearance between the pump and shaft.
Kevin 602-918-4945