What can you do to stop a small leak from a car radiator?

Answer 1

This depends on the age and value of the car and how much you value it!

If it is a very small (pinhole) leak then there is a material you can buy from most garages, called Radweld (or an equivalent). It is in effect a liquid that becomes a soft plastic with heat. You put it into the radiator water and run the engine until it is hot. As the stuff sets and comes to the small hole it blocks it. Before this stuff was invented the old fashioned answer was to break an egg into the radiator water - which had a similar effect of going in as a liquid and then blocking the hole when it sets (poached). The problem is that these solutions leave a gunge floating around in your engine water system and can potentially block or at least reduce water flow around the whole cooling system. Therefore this solution is best left only as emergency measures or for cars that have very low value.

I have not found a 'liquid metal' glue that can be applied to the outside of the radiator that is avtually up to the job of radiator repairs, although some claim to be. You may have a different experience with these than me. You would need to drain the radiator and clean the area thoroughly before using this stuff to give it good purchase - could be a little fiddly.

The next best method, and for slightly larger holes, is to have the radiator welded. Take the radiator out and take it to a welder. This should only cost a few quid with someone who is proficient.

However, if the leak has not occurred as a result of an impact then it is likely to be caused by corrosion and if this is the case, then when you have fixed this leak there are likely to be more in the near future.

The best solution is to replace the radiator. The size of this job depends on the car you have. There are different qualities and sizes of radiators available (if you intend to maintain the car for a long time you may want to upgrade).

But while you are at it you should also check the hoses too as they could be hard and brittle from age and in need of replacing too. If the radiator is corroding from age then there is a possibility that the hoses have never been replaced either. The hoses should be soft an pliable to allow for engine movement or they too may rupture.

Finally when you refill the colling system, always use a quality anti freeze as, like home radiator systems, good anti-freeze also contains an anti-corrosion agent.