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Yes you can. But obviously if you get oversized pistons then the engine needs to come out to get bored out.

 

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Yeah we've pulled the pistons with the engine still in the car so it can be done, but will take some work.

 

Getting the oil pump out of the way isn't the hard part. Getting the head and associated head-mounted parts off will be the knuckle-busting chore. Just be sure to check cylinder walls for damage BEFORE investing in new pistons.

And, since there was a damaged piston, at least check the oil pan for stray piston parts. A good steam clean, or some other comparable cleaning of the removed parts should be done, to ensure all debris is removed. Check all the bearings and journals for abnormal wear too. If you go to the expense of repairing a broken piston, you sure don't want to put it back together without cleaning out all the debris caused by the piston.

 

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There's lotsa kits out there, some without the timing chain tensioner. That's another tool you'll need.

Also, another thread mentions that the Bentley manual doesn't have the rod torque specs. Here's a copy of the specs that came with my set of rods.
https://www.northamericanmotoring.com...1&d=1444498825

And, if you don't have the Bentley manual, I highly recommend you get one. The re-assembly process is not intuitive.

Good luck ---

 

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Could i ask did anything bring this on ? orrr just normal driving / stock motor and doing the normal drive to n fro work and poof! you get a cracked piston????? --- [i.e. im wanting to know how scared i need to be adding krap on my R56 right now...]. At this rate between the factory defective timing chain/tensioner setup and various near catastrophic mechanical failures that seem to curse the R56 im wondering if i need to just slap what i got on the S model ---> sale it ---> start over and never buy a mini thats under 10 years old again...

 

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You want to know what caused your piston to disintegrate, well there's two well known reasons. Piston design is very weak to begin with do to brittle alloy and casting flaws. Tensioner, a seized vacuum pump, weak pistons, casting flaws and burnt valves do to oil coked carbon are all time bombs that can grenade your engine! Way too many badly designs parts for one generation R56!

 

What alloy is used in the casting for the N14 pistons? And importantly, where are you getting this information?

 

 

yikes! what year is the N14? 11+ or before that?


What is the alloy our pistons are made of btw?

 

In case it anyone needs simple answers and finds this through google...

The pistons aren't inherently weak, and this doesn't look like a "crack" to me. It looks like it was running extremely lean there, which would also explain why it's cleaner than the others.

I also see scraping on that cylinder wall where i'd guess really dirty or metal contaminated oil was scraping for a while. Changing the oil at 5-7500 miles instead of 10-15k like Mini wants should resolve any oil related issue.

I'm rebuilding one at 100k and a cracked #3 piston that was missing the top timing chain guide for quite a while and somehow Mini service never noticed when my brother's mother in law brought it in a fews times over the last year. It had absolutely no scraping, marks, or worn bearings and she changed the oil around 6k on average. The used replacement piston I got came from a car with only 69k miles and the black parts on pistons skirts are worn much more and there are some slight vertical scrapes above that that look pretty much the same as what's on your cylinder wall there. The rods also rocked on the pin, whereas my 100k ones had none.

So change the oil not quite as religiously as your parents may be used to, but defintely try to keep it under 7500 between changes if possible.

For the causes of cracked pistons, see this link: http://www.jmturbocoopers.com/Cooper...ton-Issue.html