SURPRISE! piece of piston in my oil pan

[garystocker]

I just got the pan down in my 5 year old rebuilt 289. I found a spotless pan inside, except for this 2" piece of piston. It looks like the ear tabs that hang down on eith side of all the pistons. I could not see which piston it came from without rotating the engine to get a look at the pistons up in the bore. The pistons on the downstroke I could inspect and they all had their ears in tact.

The car has not been driving differently at all during the last 2 years I have had it. I suspect the piece has been there since before I got it. I did notice some vibration but none so bad to attract my attention. It seems to drive fine. No shavings in the oil.

Do I leave it like it is? Re-assemble the pan and continue as I was? Or do I replace a piston. Can that be done from the bottom? Do all the pistons need to be replaced?

If I did not need to change the pan due to a leaking drain plug, I would never even have found the piston piece.

What do you think?

 

[D.Hearne]

Sounds normal for a 289/302 with the cast pistons. Don't sweat it. Seen lots of those with 100K miles on em. Doesn't seem to affect the longetivity.

 

[brianj5600]

I would have trouble driving it very hard at all. The pistons are weaker and less stable than before the pieces broke off. I have also found skirts in the pan and felt like I got away with something, but my days of beating on it were gone until I rebuilt it. I limped around until I could rebuild it. I would put it on my list of things to do. I would also replace all the pistons. If 2 broke, more might be damaged.

 

[Protowrxs]

At least you have been lucky enough in that the piece (or pieces in some cases) didn't make their way to the oil pickup, starve it, and take a bearing down. That's how I lost my first stock 351 in the 70's. I haven't run a cast piston since. Hopefully there aren't any more just hanging on. You should be able to see any cracks in the skirts from the bottom with a good flashlight.

-Stephen

 

[2nd Mustang]

Oh what surprises await when you buy a used car. My first 65 Mustang was cruising along at freeway speeds when the engine just stopped and froze. Luckily it was a three speed stick so I just took it out of gear and coasted to the shoulder of the freeway.

I couldn't turn the crank with a wrench so pulled the heads and found one piston sideways in the cylinder. Seven pop up pistons and one broken flat top.

 

[Max Power]

You could replace it if you wanted too, but you have to pull the head, and it wouldn't be balanced with the others. If you are going that deep, might as well freshen the whole thing.

 

[BlackGMC]

Have you done a compression and leak down test on it?

 

[iskwezm]

I had that happen to my old 289.Never knew it till i tore it apart, so i kept driving it normally and racing it too.

 

[jikelly]

Oh what surprises await when you buy a used car. My first 65 Mustang was cruising along at freeway speeds when the engine just stopped and froze. Luckily it was a three speed stick so I just took it out of gear and coasted to the shoulder of the freeway.

I couldn't turn the crank with a wrench so pulled the heads and found one piston sideways in the cylinder. Seven pop up pistons and one broken flat top.

Wow.

 

[garystocker]

I am glad to hear it may not be such a big deal...thanks for the input.

 

['66 coupe]

Sounds normal for a 289/302 with the cast pistons. Don't sweat it. Seen lots of those with 100K miles on em. Doesn't seem to affect the longetivity.

I had that happen to my old 289.Never knew it till i tore it apart, so i kept driving it normally and racing it too.

Interesting.
I have an old '68 block torn apart. One of the pistons is broken in the same exact way. Visually I can't see any damage to the block, which is my only concern.

 

[D.Hearne]

The original Boss 302 pistons did the same thing. But the outcome there was much worse with an 8000 rpm capable engine.

 

[promoguz]

Same happened to my 69 Mach 1 390. Bought her about 3 years ago... Drove fine no problem, always sounded great... took the oil pan out one day and found a nice chunk off of what I suspected to be a piston. Had my mechanic check it out and found 1 cracked piston, 2 burnt pistons. Good news was that there wasn't really any damage to the block.

But I agree that if you are gonna fix it.. might as well dive in and do em all.
I ended up boring out the engine just a bit, and replaced all pistons. Noticed a huge difference right off the bat.

 

[garystocker]

Now I got the oil pan in (no leaks!) and I started her up. She fired right away and sounded great. It really ran as nice as it always has, so no piston replacement for me. I think I'll drive it like I never found out.

Thanks to everyone for all the comments.