Hello & Potential 2003 Purchase
 

Hi all. I searched around for a while before registering, but wasn't able to find what I was looking for.

I am debating purchasing a 2003 MINI with several problems, one of which is a cylinder head/carbon issue. The diagnosing technician claims there is a large amount of carbon built up on the head, causing it to run poorly on cylinder #4. The CEL is on constantly and car skips and stutters. At high speeds the issue is better. It's the original owner, 5 speed manual, N/A engine. Overall, body and suspension, tires, brakes etc are good, except engine issue (and a few small trim piece issues which are incidentals).

I'm not new to repairing cars, and have thought about getting a MINI for a while (to save gas and use to buzz around, rather than my 10 mpg truck). Repairing the vehicle doesn't really bother me as I've repaired and swapped several engines in both cars and trucks in my spare time. I also work on motorcycles, building them from scratch.

The crux of what I'm interest in figuring out is:

1) is the cylinder head poor running issue common at this mileage?
1.5) if I go through and replace the cylinder head, is the bottom-end of these engines good? Or am I better off just replacing it with a reman or junkyard engine?
2) how reliable will this car be at 120K (really more concerned with common repairs, I know anything with 120K is going to break, but just wondering if, say, the transmissions are known to go at 130K, or needing waterpumps at 100K or whatever common things are known to need repairs that I should look for or proactively replace).
3) would it be easier to just swap in an S engine from a junkyard if I am going to through all the hassle of repairing the cylinder head? I assume most all harnesses are similar for engine computers, etc? It would just be a matter of getting a complete engine from the yard (including ECU and exhaust).

Thank you all for your help!

1) is the cylinder head poor running issue common at this mileage?
Carbon deposits are likely caused by running REGULAR fuel , even the standard mini's are PREMIUM only fuel

1.5) if I go through and replace the cylinder head, is the bottom-end of these engines good? Or am I better off just replacing it with a reman or junkyard engine?
It MIGHT just be carbon on the valves I pulled the heads and saw huge deposits cleaned and hot tanked and it ran fine
2) how reliable will this car be at 120K (really more concerned with common repairs, I know anything with 120K is going to break, but just wondering if, say, the transmissions are known to go at 130K, or needing waterpumps at 100K or whatever common things are known to need repairs that I should look for or proactively replace).
I'd check the clutch , Neighbor had 350K on hers third clutch
3) would it be easier to just swap in an S engine from a junkyard if I am going to through all the hassle of repairing the cylinder head? I assume most all harnesses are similar for engine computers, etc? It would just be a matter of getting a complete engine from the yard (including ECU and exhaust).
Thats a VERY VERY hard swap I've never seen one completed

Hi,
I would put in some injection cleaner though the system and octane booster should clear out the carbon deposits,fuel pump can be an issue,as can be the timing chain guides,listen for a rattle on cold start up.bottom end is strong so no issues,drain the old oil from the sump,flush the oil system,replace the filer,top up with good quality oil,and should be all good,may be worth changing the plugs and coil packs,have fun and will bring smiles by the miles,had many varieties of mini,love them all day long