Twisted ARP Oil Pump Shaft...

wow. same exact thing happened to my engine...and I mean EXACT. All my valves bent after kissing, and it broke the edges of my lifters. Apparently I forgot to put locktite on my cam retaining bolt all together though. I never inspected my oil pump shaft but it's been working.

 

VERY commen problem through the years with this particular design and more careful attention to detail is required to avoid weakening an already inherently weak point.

IMO.. anything that see's higher spring pressures/rpm should be running an aftermarket CM retaining bolt/pin.. and have the threads carefully degreased prior to applying the loctite. I've always found it odd how many don't degrease threads after degreeing/mock up and that only diminished loctites effectiveness.

Also thought I would mention as a friendly FYI here.. whenever you have sufficient torque at the oil pump shaft to do this type of damage?.. oil pump removal/teardown and inspection is always prudent(while we're on the subject of cheap insurance here) since the gear can be side loaded/forced down enough to cause galling(oil shear) of the machined surfaces in the process. I've seen firsthand what it can do on several motor teardowns(I broke a sbc chevy cam once) and oil pumps are cheap enough to replace if you swiped the machined surfaces when the failure occured. Sometimes.. they can be wet sanded and cleaned up easily if the damage in minute enough but if your nail can feel it?.. replace it while the motor is apart.

 

I hear ya...already took a look at it...gears looked brand new. Imagine that...only had about 20 whole seconds of hard run time on them lol. Pump was brand new before the incident...and still looks new on the gears. Think I just dodged a bullet with this whole mess. Could have been much worse that it ended up being.

 

Like I said in the other thread...same here. I lost an engine over it though. With mine the oil pump was locked solid. Little skinny sliver of lifter or cam lobe/cant remember which. I can still picture that tiny sliver of metal. Now that I think about it I believe it was a piece of cam lobe not lifter. They hit the lifter edges and game over. Dont assemble engines with your buddies hangin around and a case of beer. Dumb teenager at the time.lol.

 

I have to agree with the oil pump seizing up. When I first had the engine rebuilt, I took it for a test drive. I got on it pretty good lighting up the tires & continued through all 3 gears. When I let off the gas pedal, the oil light came on. It was telling me no oil pressure. I pulled the distributor & the oil pump shaft snapped an inch from the top. When I got the rest of the shaft out it was twisted perfect like a candy cane. Pulled the oil pan & found out the oil pump had seized up, from a piece of gasket silcone. I went to the parts store & got a heavy duty pump shaft & a finer screen for the new oil pump intake. Haven't had a problem since. I've been drag racing it & lots of daily driving. So far so good....

 

On the 3 separate times I’ve seen twisted pump drives we found blue silicon inside the oil pump. All three engines also had silicon on the intake and valve gaskets. You would have thought the pickup screen would have caught it

 

You'd be amazed at the small spaces that silicone can squeeze through! It can go through the pump screen, the pump, and end up stuck at a rod bearing journal! Needless to say when it stops the oil to the rod bearing, bad things happen!

 

Could be that the oil pump indeed locked up causing the cam sprocket to shear of the dowel. Good call 71 Gold.

 

There's nothing that really stands out as being wrong with the oil pump...but I'm putting a new one in just in case. If something locked it up...wouldn't it still be in there, or could it have possibly dislodged?

Hmmm...now I'm wondering. This would explain everything actually...because the cam bolt was still relatively tight. Not positive, because I didn't put a torque wrench on it when I loosened it...but it was not ridiculously loose. I didn't think it was loose enough to allow the gear to move...but, it also didn't have to move much.

Think I'm going to filter the drained oil when I get home this evening and see if there's anything in there that shouldn't be. May get lucky and find something.

I'd feel a lot more comfortable if I could find the smoking gun on this...not knowing what happened to cause it sure wears on the nerves when you think about taking it above 6500 lol

 

I agree how else would the drive twist. I did the same thing on my 418 two years ago. Small piece of the c-clip from the rocker arm made it to the oil pump. Luckly no more damage, I was at speed going throught the traps so it sheared quickly. Put in a standard oil pump and shaft, good to go.

 

Cut open the oil filter and check it for debris. If it went through the pump it will be in the filter.