So In my never ending quest to keep fluids contained within the motor I pulled the pan to put a new gasket on as it is the only source of oil escaping at this point. Finally after a day of yanking and prying I get the needed bolts out and free the pan. Low and behold there is more in the pan than just the pump/drive and some bolts. The inner skirt from piston #5 decided to go for a stroll. The wall still looks clean with no gouges.

This could have happened last week or 5 years ago. I have no idea. The motor might have 150,000 miles or any iteration there of (250k, 350k, etc...)

Mind you this is bolted in my $500 truck that has a single purpose of occasionally hauling some race bikes to the track. I also have a spare block/crank/heads laying around as well.

I don't really want to go replacing pistons right now because I might as well do a full rebuild. Now with the broken inner skirt how likely is this to cause an immediate issue? Where the truck only sees a few thousand miles a year they are highway with 4.10 gears and it spins over quite quickly at highway speeds. Will the extra allowed motion in the piston wear the bore and loose compression? could it bind up and break a rod?

Because even if its running on 7 cyliders by the time I have a new motor pieced together I really don't think this block is going to be anything other than scrap anyways. If it's likely to blow a rod through the pan my plan will be different than if it might just wear faster over the next 5-10,000 miles.

P.S. if it's not in my sig. The truck is a 1976 F-250 Camper Special, the 460 is stock and as far as I know has not been rebuilt.

 

On cast pistons they usually break from high RPM's over reving engine. For the most part they won't just break off, it broke for a reason. The skirts keep the piston from rocking back and forth in the cylinder. Who knows if the piston is now cracked and just need the right time to totally come apart. It would be something you certainly could put one piston in it and be good to go. Maybe it will last 1000 miles, could last 10,000 miles. Absolutely no way to tell. If you baby it, that would help.

 

Sounds good. It may have happened when I got curious what it would take to get to 80. Still didn't catch that prius... I'll toss it back together and keep it at 65. Meanwhile I will start putting the spare motor together for when this one lets go.