So I'm in the process of changing the oil pan gasket for the second time on my 03' R53 Mini. The first time was at 90k miles, and now it's got almost 200k on it. Runs awesome, no issues, but the oil pan was starting to leak again.

So after I pulled the pan off, I find this in the bottom. It's a small piece of a piston skirt. I looked up into the motor and found where it came from. Just a small little piece was missing. No marks in the cylinder, nothing scratched up.

The piece of the skirt down in the pan looks pretty worn, like it's been in there bouncing around for years.....

At this point, I think I'm just going to keep running it. With 200K miles on the motor, I figure that one of these days it's going to start burning a bunch of oil or some other issue where I'm going to have to rebuild it, so I'll worry about new pistons then.

What would you do?

 

I have some thoughts... But first, 200k miles and the inside of your engine looks great! Now, without knowing how long its been like that, I'd also be tempted to just drive the car until something catastrophic happens. But, in the back of my mind, I would constantly be thinking about that little piece of piston that decided it didn't like jumping around with its buddies any more.

A couple of questions I would ask myself: What is the general condition of the rest of the car? If you put money into the engine for a rebuild, would the rest of the car be worth it? If not, then just keep driving it. If an engine rebuild would get you another 200k miles, would you keep the car long enough to get that kind of mileage out of it?

 

It's a JCW that's in overall great shape. At this point, I think I'm just going to keep driving it. But like you said, I'm probably going to hold off on taking it on any long road trips......just because on the back of my mind it's going to make me nervous. But to and from work like I've done for the last 10 years.....yep! Worst case the motor comes apart and I pick up a used off of ebay for $1K and throw it in there.

 

I'd drive it!!

 

I agree with njaremka that your engine looks fantastic for 50k miles, let alone 200k! Good on you for good maintenance!

I'm always amazed at how resilient engines are - that the majority of one of the piston skirts has been broken off with no symptoms is an example of that.

I think your plan is reasonable to continue to run the car as a commuter but not trust for longer road trips, just start preparing for an engine swap or begin building your own long block.

 

Worst case scenario (which I imagine is what you're asking about)... That piston finally grenades itself, snaps a rod, and puts a hole in the block, the oil in the engine squirts out of that hole onto the exhaust manifold, and your car catches on fire.

Carry a fire bottle in case that happens. I'm assuming you're preparing to replace the entire engine anyways -- I can't imagine what an unbalanced rotating assembly could do to the crank, cylinders, etc.

 

If you haven't noticed an increase in vibration caused by the unbalanced piston, you're probably good to go. Having already gotten 200k miles out of that motor means you're ahead of the game IMHO.

 

Additional thought: AAA roadside service is only around $100/year. Might be good insurance given what you discovered.

 

I agree with keep driving it. Do you have a family or are road trips mostly a solo/spose adventure? I'd be more conservative if young kids were along.

Some of my most memorable road trips have involved a little automotive mishap. Knowing that you're dropping the oil pan you're clearly mechanically inclined. Drive it as you were before and bring an emergency bag with you on long road trips (as you should anyway). Maybe avoid the cross country stuff. But I may be a bit more adventurous than most and my road trips involve 20-30 year old cars.

 

After looking at the picture a little more.....it looks like the crack started right where one of the casting lines was. I'm guessing this was a casting defect that caused this, not a mechaincal failure inside the motor with anything hitting the piston and knock a chunk off.

 

My mini is just a daily "get to work and back" car. I've got an F250 and a BMW 335i as spare vehicles.......

Yeah....probably try to keep to shorter trips with the car now.....maybe this fall I can pull the motor and put a new piston in it? Or rebuild the entire thing.

 

Have you hand cranked the engine to check the cylinder? I know diesels can suffer piston knock where the piston can get enough play to allow the skirt to hit the cylinder wall.

Just a thought

 

Yep, the cylinder looks great, not even a scratch on it. From what I can tell by looking at the piece I found, this is how much of the piston skirt came off. Doesn't look like enough to cause issues....I think the crack started on a casting line...and then traveled until it cracked completely off.