Testing for Leaks

Leaks in the cooling system can very often be detected visually. As the engine heats up, the pressure in the system also builds up to approximately 15 psi (pounds per square inch), forcing the coolant out through a defective hose, a punctured or porous radiator tube, a porous expansion plug, or a worn water pump seal. In some cases, a defective part may not show signs of a leak unless additional pressure is exerted into the cooling system.

Installing the pressure

1 With the engine cold, remove the radiator cap, then start the engine and allow it to heat up to normal operating temperature. If necessary, add water to the cooling system, then switch the engine off. Install the pressure testing gauge on the radiator filler neck.

2 Operate the pump until the gauge needle reaches the pressure prescribed in the specifications for your engine. Caution: Never exceed the prescribed pressure for your cooling system. This may damage it by rupturing the radiator or splitting the hoses.

3 With the pressure testing gauge set at the prescribed pressure, look for leaks in the radiator hoses and connections, the heater hoses and connections, the thermostat housing gasket, the radiator tanks and core, and the water pump. If no leaks are detected, take a reading of the pressure gauge. It should maintain its reading for at least two minutes. If no visual leaks are detected but the pressure gauge needle drops slowly, there may be an internal leak caused by a cracked block, a cracked cylinder head, or a cracked water jacket. Have your car checked further by a mechanic.

4 When the pressure test is com-pleted, release the pressure in the cool-ing system, referring to the operating in-structions supplied with the pressure gauge. Then remove the gauge from the radiator.

Straightening radiator fittings You can't hammer much on a radiator inlet or outlet fitting to straighten it without running the risk of loosening soldered areas.
A quick and safe way to re­store bent radiator pipes to their proper contour is first to install a worm gear-type hose clamp around the end of the pipe. Then take any suitable half-round ob­ject and, with one hand, hold it in place against the bent part of the pipe. Straddle the hose clamp and half-round piece with a pair of pliers or vise-grips and apply pressure. This will force the bent area of the pipe out­ward to conform to the contour of the hose clamp. And there's no risk of damage.