Tips & Tricks to Fix a Steam Leak/Crack in a Car Radiator

One of the most common causes of engine overheating in automobiles is coolant leaks. Leaks can develop in any part of the coolant system on an engine. Car radiators can develop leaks because of age, corrosion and/or damage from debris like rocks or pebbles being thrown up from the road and impacting the delicate fins and tubes of the radiator. Some car radiator leaks can be repaired.

Additives

There are several products available that can be added to the coolant in the radiator to stop leaks. These additives are not effective for permanent repairs and should only be used as a last resort in an emergency situation. Additives are only effective with very small leaks and will not work with large holes or cracks. After using one of these products, take the vehicle to a professional to be repaired properly or the leak will return.

Cleaning

Any time a repair is to be made to a crack or hole in a radiator, the surface around the damaged area must be cleaned thoroughly to ensure an effective repair. If you are using epoxies, putties or sealants to plug a hole, any oils or dirt left on the repair surfaces can interfere with the material's ability to bond to the radiator and result in leaks. If you are soldering or brazing holes in a metal radiator, contaminants can cause these repairs to leak as well. Clean surfaces with solvents that do not contain any oils and do not leave any residues, such as brake cleaner, which is specifically formulated to dry without leaving any residue.

Plastic Welding

Many modern radiator tanks are constructed of plastic materials, which can rupture and crack leading to leaks and overheating. The plastic on these tanks can sometimes be repaired using a type of plastic welding that seals the cracks and returns the tanks to serviceable condition. Large cracks and holes in plastic tanks may not be repairable in this manner because the plastic used to make the tanks expands and contracts as the radiator heats up and cools down, and can cause the repaired area to break loose and fail. Some professionals advise against plastic welds entirely and instead recommend replacement of the entire radiator.

Pressure Testing

Any time a radiator is repaired it should be pressure tested. Most radiators develop between 8 psi and 14 psi of pressure when hot, and this pressure can cause a poor repair to fail and begin leaking. After repairing a radiator it should be tested using a pressure testing kit. When pressure testing the radiator after a repair, do not exceed 25 psi of pressure or damage to the radiator may result.

Leak Size

The size of the leak in a radiator is often an indicator of whether or not a repair is appropriate or possible. In general, large holes or cracks should not be repaired--the radiator should be replaced instead. Large holes or cracks usually require that some cooling tubes be pinched off or soldered closed, which results in the radiator losing some of its cooling ability. Small holes and cracks stand a better chance of being effectively repaired without the need to close off coolant tubes, causing less loss of cooling efficiency. Larger repairs are also less structurally sound and more prone to further leaks occurring.