A good radiator shop can fix the leaks by getting to them, cleaning and soldering. Sometimes a flue may need eliminating by cutting and soldering up the flue at the cut or at the top and bottom where they enter the top tank and the bottom tank. Most radiators will continue to provide sufficient cooling with several flues eliminated. The more (above about five) you eliminate the more you lose cooling efficiency. Back in the old days up to about a quarter of the flues could be eliminated(after boiling and rodding) and the radiator function well within reason.
After the radiator has been cleaned and pin holes are detected under pressure then rather than re-core some Solder Seal was used to good experience.
If there are a lot of bigger holes and the radiator man keeps having to chase them and solder or eliminate too many then it is time for a re-core job.
All the above in considered only after the radiator has been boiled and rodded. A dirty radiator is difficult to solder, even with cleaning acid, and the Solder Seal will not work very well.
Best,
Charlie
