Broke oil pump drive shaft????

[22mike]

Has anyone else had the top of the oil pump driveshaft shear off?? I was running about 7500rpms and suddenly lost all oil pressure. Pulled the motor down this morning to find it had sheared off. Oil pump is free, took pump apart no visible restriction, pulled the main caps and rod caps, no visible damage....
Any ideas on cause?? Any help would be greatly appreciated..

[setup479point2]

Would say a piece of something went through it , we broke the bottom of distributor off . If its not in the pump it may be somewhere else in there.

[mattworx]

Has anyone else had the top of the oil pump driveshaft shear off?? I was running about 7500rpms and suddenly lost all oil pressure. Pulled the motor down this morning to find it had sheared off. Oil pump is free, took pump apart no visible restriction, pulled the main caps and rod caps, no visible damage....
Any ideas on cause?? Any help would be greatly appreciated..

maybe this will help
if your running a msd make sure your using a ARP oil pump shaft we found that the size of the gear on the msd has just enough extra clearance to brake off the ears on anything other then ARP shafts when turned above 7200 . don't use melling hv55 pumps there not made for racing anymore

[stockcar5]

what kind of shaft was it? also what volume pump and what weight oil?

[TeamLFR]

Check the gear on this distributor. We broke two shafts back to back. The slotted part on the gear was off centered slightly. Enough that you could see it.

[leadfoot_35]

I've broke the shaft before as well. We use a msd distributor as well. We changed it to a chrome moly shaft and never had a problem again.

[BWRC]

Mattworx is right, seen this a lot with the shaft that comes with melling pump, jmo install new 10555 melling pump with arp shaft.