Thanks, I’m trying to see if am better off buying a rebuild engine block with the heads 

a WAG* for head gasket and cylinder head refurbish is about $1000-$1500.

For rings, about double or triple that.

Thank you for your postings, according to my son the car shutdown by itself and lost power steering, he said it could have being running hot 20 to 40 minutes.

it seems like a major job, you guys are talking like a complete overhaul!

Yes i do have access to the oil pan since I replaced last year the oil pan gasket and have access to the pistons from underneath of the engine.

how much in labor we are talking about to take it to a machine shop?
i would be doing the installation.

But by doing the wet test which is one teaspoon of motor oil in each cylinder and bring the psi up and holds it steady, according to the Bentley manual are the rings. But you guys are the experts so I would take your adviser into consideration.


I forgot to add, yes my car has electronic accelerator, and I didn’t engage the gas pedal while trying to crank the engine.

the car was towed away to my house so it was cold after couples of days the coolant was added but with a leak from the water pump.

thanks again!

If the car overheated significantly (driven while hot with no coolant) then you have warped your cylinder head enough to cause the head gasket to have lost it's full seal.

You need to have your cylinder head removed, the head skimmed (decked) flat again by a professional automotive machine shop, and you will need to replace your head gasket and head bolts as well. The bolts have been stretched and are required to be replaced with a head gasket change.

While the head is at the machine shop, you can have them check the valves to make sure they are not warped/bent or damaged in any way.  Most people would say that you should go ahead and get the head rebuilt completely since you are going through the effort of removing it anyway to get it skimmed flat again.

When the head is removed, you can inspect the cylinder bores and pistons themselves for evidence of damage since they will be visible.

Rings are the last thing I would think about replacing after an engine overheats. They are really robust and forgiving. The cylinder head and valves, not so forgiving.

Gus:

(If any posts appear from "Specialist", ignore them - he isn't one!)
I'm a classic Mini owner, so can't advise directly about a 2006 BMW MINI. But here's some thoughts:

Extremely low compression readings sounds to me more like valve issues than rings. If I got a zero reading, I would suspect my methods or the compression tester. Typically compression is taken on a cold engine with the throttle held wide open. I'm not sure if your MINI has an electronically controlled throttle if it has an actual mechanical cable. An electronic throttle probably wound not open fully as it would be governed by a computer (or six!) to an optimum position under normal starting conditions.
I doubt you could replace rings without pulling the engine - you'd have to get under to see if the oil pan can be removed to gain access to the crankshaft to disconnect the connecting rods and then push the pistons out.

If you have the engine that far apart, you would inspect the cylinder bores for damage or scuffing. At least a light honing would be a good idea. Otherwise the new rings might not bed in properly or war prematurely.

Damage to an overheated engine would depend on how hot and whether a computer shut it down before major damage. Typically, when an engine gets too hot, the pistons expand and get tighter in the cylinders, increasing the friction and the engine loses power. If the loss of power is noticed and the engine shut off and allowed to cool down slowly and gently and coolant is NOT added until the engine is stone cold, it may cool and contract back to what it was with no major damage. If it cools unevenly or coolant is added to a hot engine, it will contract unevenly and gaskets will suffer - most likely the head gasket will leak from cylinder to cylinder (which a compression test might diagnose) or from cylinders to the cooling or oil systems (you'd see contamination of the coolant or oil or both, or oil or coolant smoke at the tailpipe.

You should be able to rent an engine crane for a reasonable cost.

I have the Bentley manual so you would know.
my car was used by my son last December and somehow the coolant got depleted therefore it got overheated, the car stop and it got towed to my house until now that I m troubleshooting it.
November of last year I installed a brand new water pump and I changed all the coolant hoses and it seems that there was no obvious lost of coolant on the driveway so one could suspect to check the engine compartment.
its my own car but my son came and used it and of course they drive without checking anything in an old car. They drive it as new car!
after car got overheated it was noticed that while I was pouring coolant there was a obvious leakage on the brand new water pump, I replaced it with another one since still under warranty:
so while try to start the car the engine rotated but not starting I used my code reader and it gave me the code p340 the camshaft sensor I bought the sensors both crankshaft and it got replaced, and still engine rotate without starting, I google it and they said it could be battery, starter or sensors that’s why I replaced them.
finally I read in order for a car to start it requires 4 things compression,spark, gasoline & air.
check for spark ok, gasoline ok, air duct was not obstructed, so my final steps was compression, I should have started from there first before even changing sensors, anyways my readings from cyl 1,3,4 were less than 40 psi in each cyl. And cyl 2 was zero readings no compression, so then I further read before taking down the engine it needed a wet compression test to check for temporarily seal using motor oil, and indeed the compression improve from a range from 90 psi to 149 psi but still low in range values it should be 167-247 psi range for a base Mini Cooper 2006,

my questions?
can I replace the piston rings without removing the engine from my car?
can I replaced just the rings and not worry about the piston chamber?
what are the damages after an engine shut off by overheating?

i don’t have an engine lifter 
Sorry for the long explanation
Im not a mechanic but am sort of handyman when come to fix stuff.

Gus 
Miami Florida