Radiator paint bubble with rust on top

[masamune]

I noticed a little rusty drip of water from the top of the radiator the other day. There is a bubble of paint that can be pushed in, the size of my thumbprint.




I read in here this is a pinhole leak, radiators are rusted and have to be replaced asap...
Isn't this a weird spot for a leak? Has my radiator packed it ?

I don't know when it was originally fitted, we had a power flush 4 years ago and inhibitor in the system up until last year (until some people and viessmann said they only recommend potable water). I service the boiler every year, heating engineer said the magnaclean filter was generally clean.

It is a double P radiator around 2 meters long

 

[terryplumb]

Looks like you need a new rad. Inhibitor helps to slow down the oxidisation process ,it inhibits it !! It does not totally prevent it .

 

[Mottie]

Pinhole in rad. Ours went the same after we had a chemical clean and flush and the system was converted to a sealed one. Mind you, it was 50 years old!