So, rad caps, are a very important part of, the engine’s cooling system.

But, most of the time, no one pays attention to them, until it’s too late.

Most of today’s cooling systems, also include, an expansion tank, that also has a cap. And, that cap, is equally important. Because, it is critical, that pressure must be maintained, at all times.

So, damaged rad caps cannot effectively, seal off the system, nor keep, it properly pressurized.

So, What Are The Basic Functions Of Rad Caps:

  • They keep the cooling system sealed, from outside contaminants.
  • By keeping pressure in the cooling system, they raise the boiling point, of the engine coolant.
  • Rad caps, allow coolant to flow to the expansion recovery tank, when coolant gets hot, expands, and pressures increase.
  • As the system cools down, they allow coolant to return to the engine, from the expansion recovery tank.
  • The above function also help with, stopping extra outside air from, entering the system.
  • Extra air in the system, will cause air locks, resulting in overheating.

So, a bad radiator cap, can cause the engine to overheat, at lower temperatures. As a result, this will cause the coolant, to boil over to the expansion tank. Rad caps that are faulty, could also prevent coolant from, returning to the engine. This would create a vacuum and cause, the radiator hoses to collapse.

There are several warning signs, that your radiator cap is not working right:

Leaking Engine Coolant

If your coolant is leaking, it could mean your radiator cap is bad. If the cap isn’t releasing excess pressure properly, that pressure can force the coolant to leak. Usually, at the point of least resistance. This can be from the rad caps, a hose, engine gaskets, the water pump or even from, the radiator itself.

Engine Running Hot And Overheating

If your temperature gauge starts reading high, your radiator cap, could be at fault. It could mean the cap is, failing to maintain the correct pressure.

Overflowing Reservoir Expansion Tank

Coolant flows into the reservoir tank, as it expands. The radiator cap is, released by the pressure and the coolant, flows toward the overflow tank. With a bad rad caps, the coolant will get released too quickly and cause, the reservoir to boil over.

Collapsed Radiator Hose

You may have a bad radiator cap, if a radiator hose collapses. Vacuum won’t be released by the radiator cap and will cause, the radiator hose to collapse.

Air Inside the Cooling System

When your radiator cap does not seal properly, air will get inside of the cooling system. Consequently, this will cause air pockets to get inside of the, heater core, thermostat and radiator hoses. As a result, the engine will start to overheat, because it cannot sustain a temperature, that is consistent.


Choose Rad Caps Help Topic Below

Bad Radiator Cap – A Cheap Fix For A Potential Disaster

Radiator Caps – This Fairly Cheap Part Is More Important Than You Think

Radiator Cap – Basic Function – Failure Symptoms – How Important Is It


Thank You !