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Exploded pinion gear

2947 Views 5 Replies 4 Participants Last post by  Thermodyne
Hello to all,
I’m new to this forum but it seems like it better than the others I’ve been on. But anyway I’ve got a 93 dyna low rider w/ ultima ignition, ev27 cam and fishtail exhaust. I haven’t had it for too long but been wrenching on it ever since.
my question is what would cause the pinion gear to explode? Here’s a little background in the situation. Oil pump wasn’t working so I went in and found that the key way was gone from the pinion gear there was no damage to anything luckily so got any key and fixed it I ran it for a couple times after priming oil pump then on the third time I was going to run her all it would do was spin. No fire, no compression. I checked everything that it might have been on the outside(good). Just opened the cam chest and found pinion gear in 3 pieces sitting in the bottom. But there’s no damage to anything else which is a blessing but wondering what might have caused it. The gear wasn’t in perfect condition by no means but it got chewed up pretty bad. Any feedback is appreciated and welcomed

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Hello to all,
I’m new to this forum but it seems like it better than the others I’ve been on. But anyway I’ve got a 93 dyna low rider w/ ultima ignition, ev27 cam and fishtail exhaust. I haven’t had it for too long but been wrenching on it ever since.
my question is what would cause the pinion gear to explode? Here’s a little background in the situation. Oil pump wasn’t working so I went in and found that the key way was gone from the pinion gear there was no damage to anything luckily so got any key and fixed it I ran it for a couple times after priming oil pump then on the third time I was going to run her all it would do was spin. No fire, no compression. I checked everything that it might have been on the outside(good). Just opened the cam chest and found pinion gear in 3 pieces sitting in the bottom. But there’s no damage to anything else which is a blessing but wondering what might have caused it. The gear wasn’t in perfect condition by no means but it got chewed up pretty bad. Any feedback is appreciated and welcomed
My apologies. It’s the oil pump drive gear.
Pull oil pump i suspect it to be the cause
THe oil pump must spin free with fingers after being tightened.
Slide the crank gear off to spin the pump by hand.
If there is any binding of the pump, it will eat the gears.

To split a oil pump drive gear is rare I would guess caused by something going through the gears.
Or if it was driven on with the key rode up and borked.
It may have bent the oil pump shaft! :oops:
THe oil pump must spin free with fingers after being tightened.
Slide the crank gear off to spin the pump by hand.
If there is any binding of the pump, it will eat the gears.

To split a oil pump drive gear is rare I would guess caused by something going through the gears.
Or if it was driven on with the key rode up and borked.
It may have bent the oil pump shaft! :oops:
Leave it to me to do something special lol. I’m gonna check out that shaft here in a little bit thanks for the reply. If the rifling ( not sure if that’s right) or the grooves on that gear were too worn down, could it have jumped to the wrong section of track? When I opened the chest, the second thing I noticed was the pinion gear was off time by quit a few teeth and I know I set it right cause I had to take the nut off the pinion gear to see the timing mark on it
Which gear are you calling the pinion gear? The pinion gear drives the cam, they come in 7 select fit sizes. To fracture it would require damaging it during the service process. Something like dropping it or using the wrong puller if its stuck on the shaft. The gear that drives the oil pump is called the oil pump drive gear. They can be cracked in the process of cutting the drive key. But usually they are damaged because the key moves during the installation.
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