Two quick questions:

- I’ve got a manual transmission. Can’t I put it in gear and pull the crank bolt off? Do I need the tool?

- I found this oil on the back of the engine brace( to the rear of the engine mount. What’s the source? Will changing the valve cover seal be enough or is it more than that?

 

You should be ok removing the crank bolt without locking the crank, but installation of the timing chain will require the timing and crank tools to be used.

For the oil… for it to be coated like that in that area, I would suspect the cam cover gasket.

 

In the beginning you mentioned they changed the short block? Oh well..

For good measure check the vanos solenoid and tensioner seal. The timing chain kit should have a new tensioner anyways.

 

yes, the kit I bought has a new tensioner. I don’t think it has a vanos seal. I’ll have to check the cam cover to see if there’s a crack. I thought I read somewhere the covers can go bad.

 

The verdict is in…I have absolutely no clue what is wrong.

the good news is the cylinders look clean

the #3 piston has more crud than the other three, same with the #3 valves

i poured acetone in #2 and #3 and they don’t seem to be draining.

I can absolutely confirm I had a misfire isolated to #3. I swapped plugs, coils and disconnected the coil electrical connection. The vibration never changed on #3 and got rougher on all the other cylinders.

when doing the compression check, I did all 4 cylinders twice, disconnecting between checks. I’m reasonably certain my measurements were good, but???

help!!!!!

 

Maybe it's just the picture, but the spot circled on #3 piston looks suspect to me.



Maybe pour some motor oil on top of the pistons and see if it runs out of #3 faster than the others and/or flip the block over and have a look at the bottoms of the pistons?

 

Oh my!!! I missed that!!! Short block is 15k miles and 1-2 years old. When the dealer did it, they said there was no warranty. Maybe they didn’t record that!! I’ll call.

if not under warranty, can I replace only the one piston & ring? Odd that the cylinder looks good.

what are my next steps?

 

Was that a new block, or a used one that they put in? Just curious.

 

Brand new out of the box so I was told. I did see the box where the old engine was supposed to be when I picked it up. In short, I bought the car used from the Mini Dealership - it had been a track car of some sort. During my research on the car I discovered the engine had been replaced and confirmed it was from a mini dealer and asked if the work was under warranty. They said yes. Fast forward 6-8 months and it blew. I had absolutely no documentation about the verbal warranty. The new service manager contacted the old service manager who remembered the verbal conversation. Amazingly, they honored it! Incredible dealer experience to say the least. I looked at the invoice - 15k miles and 3.5 years later it blew. I doubt it's under warranty but will check.

 

Looks like you found the source of your compression check results!

That really stinks, but also looks like the cylinder liner is still salvageable.

 

Any thoughts on replacing the single piston vs replacing all 4?

any recommendations on which pistons to use?

 

I would ask myself:
- How long do I plan to keep the car?
- Do I want any performance benefit?
- What kind of budget can I put together?

A 2011 JCW will be a fun car to keep for a while, and after rebuilding an engine, I would want to make sure I get a few more years of smiles out of it. It's also tremendously satisfying to fire up an engine after rebuilding it.

If it were me in your position, I would look at forged rods and pistons, and performing a general refresh on the block and head - get everything back up to snuff, since its torn down already.

On the other hand, I can understand not wanting to sink a bunch of money into it, and just get it back on the road...

Maybe check out https://www.allmagautoparts.com/?

 

I’m trying to get the piston out and it gets flush with the block and there seems to be interference. I’m pushing it up with a screwdriver on the back of the rod where the bolt was.

should I use a Mallet to coax it? I’m sensitive about scoring anything.

 

There could be just a slight ridge at the top of the bore, just need to get the rings past it

 

You're right. There was. I coaxed it out. Well...It looks like I found the problem. I wonder if there was a manufacturing defect in the piston that gave it that straight edge and it didn't seal properly from day one. You can see how pressure caused the ring to bend and eventually break off what was underneath.

There's a slight rough spot on the cylinder wall. Do you think a honing tool would take care of that? If so, recommendations on which one to use?

I appreciate everybody's help in getting to this point - what an asset this board is!!

I'll start another thread soon on getting this thing put back together

 

Oooof

I don't think its a piston defect. That's is an almost common occurrence on neglected N14 engines. They get some carbon build up, it turns into a hot spot, then either a valve breaks or the piston melts.

 

thanks, what do you mean by neglected? The engine had 15k miles so I couldn’t neglect it for too long . In all honesty, what do you mean so I don’t do it again.

do you think honing will cure the cylinder wall?

sounds like I’m changing out all 4 pistons just in case.

 

Well, probably depends on how risk tolerant you are, willing to redo the work, or willing to take out the engine for a machine shop to treat the walls.

 

If you are replacing the piston and rings, you will at least want to hone the cylinder to help the new rings seat.

Make sure you're running a low volatility oil, make sure the PCV system is operating, and I would run a catch can in the rear PCV line. You might also replace the valve cover, since it houses the PCV check valves. If those get choked with oil, they start bypassing more oil and vapors, which lead to carbon build up.

 

How risky are the 9.5 pistons for a daily driver- not worth the risk?

should I do anything with the head?

 

How deep is your budget?

If it were me, and I think I said this before, I would at the least want to refresh everything, use high quality fasteners where available, and give serious consideration forged pistons and rods. Since you are starting with a JCW, the options for even higher performance are there.

 

Should I measure the bore for taper and round or is it not a risk?

mid so, do you have specs?

 

OP: Did you ever confirm with Mini that the block was replaced?

Nothing in your pictures really looks like a low miles engine.

How many miles on the car?

You need to pull piston #2 as well.

 

I confirmed it’s not under warranty. The invoice I have says the short block was replaced. Other Than than that I don’t know the dealership can offer anything more. I’ll check tomorrow to see if there are any numbers on the block I can trace.

135k on the car, 15k on the short block. In my opinion, valves look good except for crud on 3.

all pistons are pulled and will be replaced. New CP forged pistons on all 4, same rods.

welcome thoughts

 

From what I can glean from an online search the damage shown is a classic case of detonation caused failure.

Suggest you either replace or have your injectors professionally cleaned.

Curious why you have chosen 9.5 pistons.