Tips for Fixing a Truck Engine Coolant Leak

An occurrence of an engine coolant leak can be easily discovered as it drips from the source. By opening the hood, a visual inspection of the engine would be all that needs to be done. Usually, the coolant leaks from the radiator, freeze plugs, water pumps or the hoses. Other kinds of leaks that might exist are the internal leaks which occur inside the engine and cannot be seen from the outside. They may happen due to cracked head or bad head gasket. Repairing these leaks is more costly because the engine has to be dismantled to investigate the source of the leak.

Fixing the Leak

If the leak is external, going to the service station can be avoided by following some simple steps based on the leaking component.

  • Radiator Leak: The first option is to use cooling system sealer, cheap bottles of which are easily available in the market. All small leaks can be sealed by their application and can provide a temporary solution. The second, a more permanent option is to solder the leakage area with parts of older radiators. The second method involves a lot of hard work and is not applicable for heavily corroded or damaged radiators.
  • Freeze Plug: Again, there are two ways of corrective measures that can be taken. One can choose to seal the hole of the plug with sealing solution or just clean the surface by using sandpaper while using two-part epoxy to pack it. Remember to keep the plug straight at all times or the sealing effect may not work.
  • Water Pump: The only solution to this kind of leak is to replace the pump. Be careful while doing so as some models have common bolts for the pump and the timing cover. There is always a risk of displacing the latter if proper care is not taken. Check the fan clutch while at it as it also has the same lifespan as the pump and may need replacement too.
  • Hoses: Bad hoses need to be replaced too as no sealers work here. If possible, check all the other hoses and replace any that have wear and tear. The clamps for these are prone to losing tension leading to gripping problems.


Once the leak has been fixed, the refilling should be done with 50/50 mixture of water and antifreeze. This preserves the system from corrosion and freezing. Although, the best way to do it is to completely fill the system with the coolant. Start the engine and let it circulate. Keep the heater on so that the coolant can flow through it. When the coolant has circulated throughout the engine, replace the radiator cap.

Pressure Testing

The most preferred way to check the pressure is by adding additional load on the cooling system by either taking the vehicle for a drive or starting the air conditioner. After a while, stop and check the engine area for leakage. Other mechanism is to use the pressure testing tools which have vacuum pressure gauges. The system would lose pressure in case of leaks.