My k75 has just developed a leak on the lower rt side between the metal rad body and the plastic side- looks like the seal behind the metal to plastic crimping has failed. Is this repairable?

Thanks
Bob

I would get a used radiator.  Radiator leaks are pretty rare, yours is the first I've seen in a number of years on forums.   Replacing your leaky one is the fastest, most reliable fix.

The radiator on LFB sprang a leak earlier this year, about 6000 miles ago. I chucked a bottle of Radweld in and that sorted the problem. Mind you, there's a backup radiator hanging on the wall just in case, but Murphy says I'll never need it now.

https://www.holtsauto.com/holts/news/radweld-work/

Mine split a couple of years ago, after some searching on ebay I got an 1100 radiator (complete with cap, the final revision and the one that actually reliably works!) for £35. There are loads of them about, but for you I guess postage may be an issue?

Can you describe the "final revision?"  I was under the impression that the only change made to the radiators was when the early 3-row models were later replaced by 2-row radiators.  
There are all aluminum radiators on offer on eBay.  They apparently are made in China.  They are quite nice in appearance.  I wonder who has had personal experience with one.

You should be aware that a K75 radiator is about 290mm across it and the K100 is about 330mm, if you have a K75 with a radiator cowling it will matter.
On the other hand it might just need a squeeze to re-crimp it

brickrider2 wrote:Can you describe the "final revision?"  I was under the impression that the only change made to the radiators was when the early 3-row models were later replaced by 2-row radiators.  
There are all aluminum radiators on offer on eBay.  They apparently are made in China.  They are quite nice in appearance.  I wonder who has had personal experience with one.

i have seen pics of the insides of one of those radiators
and I wouldn't be ordering one at all ..

whilst the outsides looks fine   the finish is crappy internally with dags of metal obvious everywhere ...they might indeed work , but for how long ??

That's unwelcome news indeed, Charlie.  If (when?) the OEM radiator goes tits up, there are few options apart from very expensive BMW spares.  I've tried to repair a couple of K100 radiators and both were failures. 

brickrider2 wrote:Can you describe the "final revision?"

I think there are three versions of rad cap, maybe four. They get progressively better at working/not blocking up until the final version which came on the 1100s which finally seems to be reliable. Mine had started to collapse the pipe that goes through the crank cover as the system couldn't breathe in and was a vacuum - it seems to be a common complaint.

As an aside, mine has run rich/cold ever since I fitted the later radiator - anyone know if this is normal? I am cretinous enough to have reused the washers on the temperature sensor/plug though so it could well just be that making the connection a higher resistance than it should be.

An update on the leaky radx turns out there is nothing wrong with the rad, a pinhole leak in the rad hose was the issue - has been replaced and all is now drip free. Thanks for the comments and suggestions!
Bob

Isn't it nice to find it's the cheap/easy bit!