Is Thermal Shock Causing Your Gasket Issues?

September 26, 2018
min read

Head gaskets fail for a variety of reasons. Troubleshooting what’s going wrong can be frustrating.

Why Do Head Gaskets Fail?

There are many reasons for head gasket failure, including:
  • Damage from bolts that hold the head gasket in place
  • Excess pressure and stress in the engine
  • Overheated engine
  • Too much boost from a turbo charge
  • Thermal shock within the coolant system
As you can see, thermal shock isn’t the only reason for a head gasket to fail, but it is a common one. Since it is expensive to fix head gasket problems, it’s important to do what you can to prevent them. This includes avoiding thermal shock.

What is Thermal Shock in the Coolant System?

Thermal shock occurs when temperature differences inside the cooling system cause different parts to expand and contract, placing a strain on the system and causing cracks to develop. When this occurs, the head gasket fails.

Commonly, cars are prone to thermal shock when their radiators are located far from the engine and have a greater cooling capacity than the engine really needs. As water flows from the water pump to the radiator and back, it cools off due to the length it must travel. The shock of the cold water turns off the thermostat, which needs hot water from the flow of coolant to work properly.

The thermostat will return to its normal operation once it receives the warm coolant. Meanwhile, the engine continues to work and heats up, increasing the risk of overheat. When the warm coolant finally opens the thermostat, cold water floods the block.

This whole cycle keeps happening, subjecting the head gasket and the engine to excess strain. Finally, the shock is too much and the gasket blows.

Fixing Gasket Issues

There are a couple of ways to get around this annoying cycle and keep your car running smoothly.

Remote thermostats with by-pass valves can be spliced into the engine’s outlet hose. By shortening the distance between the heater and thermostat, the remote thermostat prevents the cool fluid from closing the thermostat. As a result, you can avoid thermal shock issues.

If you don’t mind a longer warm-up time for your car, you can move the thermostat to the front of the car, then connect the by-pass at the radiator’s return pipe. This option keeps more water at engine temp, avoiding the temperature fluctuations that lead to thermal shock.

Either of these techniques should solve your gasket woes if the cause was thermal shock. If you still experience gasket issues, work through the other causes of head gasket failure until you find the right fix.

Find Aftermarket Thermostats

MotoRad stocks a huge selection of aftermarket thermostats, coolant caps, and more. Get what you need to fix your gasket issues at a great price. If you need more assistance, we’re happy to recommend products for your vehicle make and model.


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