Quick Answer

Can I use a 16 psi radiator cap?

Use one with the psi rating that the rest of your cooling system was designed for. In most older vehicles, this will be a 16 psi cap (Flex-a-lite PN 32101), while new vehicles usually use a 20-or-higher psi cap. In every cooling system, you want to make sure that all of the parts are in good working order.

What psi should my radiator cap be?

Most radiator pressure caps keep the system pressure at 16 PSI so the engine coolant can get considerably hotter without the fear that it will boil off.

What happens if radiator cap pressure is too low?

Internal pressure fluctuations can cause warping and/or tearing of the hoses. When the pressure gets too low, it causes a vacuum effect which collapses one or more hoses. Overpressurization can also cause cracks in the line. When inspecting the cooling system, check that no hoses are hard or feel spongy.

What happens if I use a higher psi radiator cap?

A high-pressure radiator cap is used to raise the boiling point. This protects the system from boiling over at the top of the operating temperature range. High-performance engines also create more heat. Higher pressure caps can boost the boiling point even more.

Does radiator cap pressure matter?

And the boiling point increases 2-3 degrees for each additional psi of pressure in the system. So the over-simplified answer to the tech quiz is that, yes, a higher pressure radiator cap can help prevent overheating.

How do I know which radiator cap to buy?

Know the Pressure Rating

Each cap is different depending on the model of your car. The owner’s manual often has the correct pressure rating listed that is necessary for your car. If the pressure rating is not listed in the owner’s manual, it will be under the hood on top of your old radiator cap.

Why are radiator caps pressurized?

A radiator cap keeps the cooling system pressured which raises the boiling point. For every pound of pressure in a closed cooling system you raise the boiling point by three degrees. At sea level, water boils at 212 degrees. By adding 16 pounds of pressure to the system you will raise the boiling point to 260 degrees.

What does a 15 psi radiator cap do to the boiling point of antifreeze?

A standard coolant mixture of 50 percent water and 50 percent ethylene glycol (such as our own DeWitts High Performance Coolant has a boiling point of 223 degrees. A cooling system using a 15 psi radiator cap will add 45 degrees to the boiling point for a final boiling point of 268 degrees.

Does the radiator cap have to be the highest point?

The radiator cap should always be located at the highest point of the cooling system, and on the low pressure side (after the radiator core). Cross flow radiators mounted higher than the engine are ideal because the cap is on the tank that is connected to the water pump inlet.

Should I see coolant when I open the radiator cap?

Wait until your car’s engine has cooled down completely before opening the cap, or simply check the coolant level before turning on your engine. If you can see coolant in the radiator, and it’s near the top (approaching the cap spout), then you don’t need to add any additional antifreeze.

How tight should a coolant cap be?

It should be moderately hand tight. Nothing major but a solid hand tight will do. You can feel it bottom out and when you do, just snug it up a little. You are only stretching things when you keep turning them after they bottom out and they will eventually break if they are tightened too tight too often.

What size radiator cap do I need?

How to Choose the Correct Radiator Cap

FILLER NECK WIDTH (outer dimension) FILLER NECK DEPTH OVERALL DIAMETER
32mm (inner dimension) 16 mm 1.77″
2.2″ .75” 2.3”
2.2″ .75” 2.3″
2.2″ .75” 2.3″

What is the highest pressure radiator cap?

Speedway High Pressure Radiator Cap, 29-31 Lbs

  • This high pressure racing radiator cap works well for cars that run at high coolant temperatures.
  • 29 to 31 psi coolant system pressure raises the boiling point of water or coolant mixture and reduces the chance of overheating.

What does 1.1 mean on a radiator cap?

A standard 1.1 bar cap adds 48 degrees to the boiling point of either fluid. So the coolant in your car will not actually boil until ~260 degrees, or ~271 degrees if it has antifreeze mixed in. Adding the additional 0.2 bar of pressure gives us another 8.7 degrees in both cases.

Why is coolant coming out of my radiator cap?

If the cap isn’t releasing excess pressure properly, that pressure can force the coolant to leak out at the point of least resistance. This can be from the cap, a hose, engine gaskets, the water pump or even from the radiator itself, especially if you have an older vehicle with lots of miles on it.

Are all radiator caps universal?

Radiator caps can come in all shapes and sizes unique to your car’s radiator. Different vehicles have different systems and therefore work with individual pressures.

Why does the fitting of a radiator pressure cap make the system more effective?

By allowing that pressure to increase, the coolant’s boiling point also increases to around 125° C at 15 psi / 103 kPa, which means the fluid in the cooling system can absorb even more heat from the engine without boiling.

What is the most efficient way to increase a radiators efficiency?

That being said, Great Rads have put together a list of the top 4 ways to help you improve the efficiency of your radiator.

  1. Use reflectors and stop heating the streets.
  2. Regularly clean your radiator.
  3. Bring into play radiator additives.
  4. Check if there are any cold spots.

What temp does water boil under 15 psi?

Whereas water boils at around 212°F. at atmospheric pressure, if exposed to 15 psi (a common radiator pressure cap), the boiling point will now be 45°F. higher (3 psi times 15 psi cap). Under this pressure, water boils at 257°F.

How much is the boiling point of coolant increased when using a 13 to 15 psi radiator cap?

Water boils at 212° F, increasing the pressure in a closed system increases the boiling point. This means that a cap rated at 13 lbs. will increase the boiling point in a system by 39° F.

What temperature can I open my radiator cap?

Don’t open the radiator cap until it is cool

Note that an overheated engine may have a coolant that is as hot as 260 Fahrenheit. Inside the system is sealed. Unfortunately, once it is exposed to air, it will boil and can cause severe burns to you. Wait until the system has completely cooled.