What happen to my piston?

83RagTop5.0

Member
Jun 29, 2019
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Seattle
Hey guys little back story. Bought this car off an old man for 1200 bucks. Said he bought it from his wife’s coworker who was hurting for cash. Had for 2 years and was selling the rental house where he had the car parked. So the car had to go. Man said he replaced the carb and battery and it started up. I drove it about five miles it was fine. Good power. For what it is. Sounded good.
Took it home. Drove it again about a week later to a nearby town and back. 30 miles round trip. About a half mile from my house on the way back the motor was badly off balance and kept wanting to die unless I was punching it. Make a weird loud maybe squeal like sound if I recall correctly. Started it back up and punched it all the way and parked it. Just had the chance to move and now have a place to work on the car and I tore the block down. I found three things that were out of place or odd. The oil pump shaft from the distributor was snapped. Piston number 4 and corresponding on the block was damaged. Stuffed up severely. I’m entirely new to all of this and have decided to go with an explorer 5.0 build but am curious as what would cause the piston to do that? Snapped shaft and no oil getting there?
Any input would be greatly appreciated.
 

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Wayne Waldrep

Before I post a pic, do you have one of yours?
15 Year Member
Apr 14, 2003
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So #1...just my opinion but it would be nice if this were in your other engine thread so all the details are right there and easy to keep up with...but ok.
#2 broken oil pump driveshaft = no oil = engine seizing up. Why? That I can't tell ya.
Bonus suggestion: when buying an unknown project don't count on driving it home. Especially if it's making funny noises and not running correctly. You are just causing yourself more trouble....see pics above! :D
 

Steel1

Advanced Member
Aug 18, 2017
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I once made a twizzler out of an ARP oil pump shaft, didn't break it though.
It was caused by a piece of rocker arm snap ring that had come off and somehow got lodged in the oil pump.
Good times, good times.
 

7upstang91

10 Year Member
May 30, 2008
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I once made a twizzler out of an ARP oil pump shaft, didn't break it though.
It was caused by a piece of rocker arm snap ring that had come off and somehow got lodged in the oil pump.
Good times, good times.
I did the same when I was 18. Broken the oil pump at the track and drove the car home 30 miles. Pulled the motor apart to find the oil pump shaft twisted around the crank, fun times for sure. I learned a valuable lesson that day.
 

deathb4dismount

Crap, didn’t realize my crotch was in that picture
5 Year Member
Oct 6, 2011
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Same here. Oil pump turned into a twizzler on 95 coasted off the highway and into the driveway. You answered your own question in your question. No oil.
 

John Dirks Jr

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Jun 28, 2013
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Snapped oil pump drive shaft would hurt the bearings and top end components. But, the oil for the piston and cylinder wall comes from the rotating assembly skimming across the oil in the pan as the engine is running. Certainly, a broken pump shaft is a fatal thing, but if your oil level is correct, the cylinders and pistons should still get adequate lube. So for that piston and cylinder to be starved of lubrication, the engine had to be run a substantial amount of time with very low oil in the pan.