I did a search and didn't see anyone with same problem, so I thought I'd share my experience.

Back in 2009, my 05 MCS had a coolant leak somewhere on the passenger side of the engine bay, because that side looked like it had been sprayed with coolant. I didn't get into any accident or hit anything. I hit the occasional pot hole every now & then, but nothing really major, so I thought it was just a loose or bad hose. Turns out the inlet hose connector on the radiator had cracked, and since it was plastic, it couldn't be repaired, it had to be completely replaced. I was told it was a freak accident and that it didn't occur very often (which I confirmed by searching on these forums back then). So without thinking twice, I had it replaced with a brand new oem radiator.

Well, 4 years later, it happened again. Same coolant spray pattern from a crack in a similar location. And like before, no accidents or collisions or anything. Seriously, what were the odds?!?! I was furious. I'd like to meet the genius bmw engineer who designed this aluminum radiator core with plastic inlet/outlet hose connections and punch him in the face.

So this time, I'm replacing it with a Mishimoto radiator. It costs about the same as oem, if not a little more. It's all aluminum so no worries about any plastic cracking, and it has a "no questions asked" lifetime warranty, which is self-explanatory. I know it may be a bit overkill for normal driving conditions, but I'll have the peace of mind that if anything else were to happen again, the radiator would be covered.

 

WOW...wonder if the hose clamps were put on too tight?!
I think that is the ONE advantage of the factory style hose clamps as opposed to the screw type!!
Aftermarket exact fit replacements can be found for gen1 MINI's for under $100 (80+shipping, them minus the usual 5 or 10% for a coupon code) on rock auto, etc...

Example is a 2005 S 6 speed S
The all aluminium Mishimoto is pretty.....bet it has a bit more capacity too..never a bad thing on a modded car!!

 

PS..almost EVERY OEM radiator I have seen in the last 10 years or so has the SAME design as the MINI.... plastic ends with plastic hose connections, heat crimped to the metal tubes in the middle. Cheap, light, and fast to make.... think most folks get 10 years or so from them.

 

While I've never experienced your dilemma, I can say that the Mishimoto is a great part. I've used the radiators on previously owned cars (they have all been modified) and all was fine. Great fitment and quality. I truly hope that it solves your problem, but I think it will

 

I didn't know that design was common, though I did figure it was designed that way to save money on manufacturing. I guess I really do just have bad luck.