What Does It Mean When The Upper Radiator Hose Is Hot And The Lower Radiator Hose Is Cold?

Your top radiator hose is hot and the bottom hose is cold because the different radiator hoses are doing their jobs and your radiator is in perfect condition. The job of both radiator hoses is to transport coolant in and out of the radiator but the coolant transported in both hoses is not of the same temperature.

Should my upper radiator hose be hard when engine is warm?

While the engine is warm after a drive, squeeze the radiator hoses, paying particular attention to areas where the hose bends. A radiator hose in good condition should feel firm, but not hard.

How hot does a upper radiator hose get?

The upper radiator hose should be hot, around 190–200 °F. (The safest and most accurate way to get this temperature reading is with an infrared thermometer.)

Why does my lower radiator hose not get hot?

So, what causes a lower radiator hose to stay cold? The most common reasons why your lower radiator hose is cold are a faulty thermostat, bad water pump, or low coolant level. It can also be caused by airlocks or a clogged coolant system.

How do I know if my radiator is blocked not circulating coolant?

  • Leaking coolant. Scroll to continue with content.
  • Discolored and thicker coolant. You know your coolant’s original color, don’t you?
  • Damaged water pump.
  • Excessively high gauge temperature readings.
  • Blocked, bent, or damaged radiator fins.
  • Should bottom radiator hose be hot or cold?

    Under normal circumstances, a cold lower hose will only be present when you first start the car with a cold engine. Once the engine warms up (after about 5 miles of driving in summer), coolant flow will begin and will heat the upper hose and the radiator.

    What does it mean if your top radiator hose is hard?

    hard hoses can be a sign of the cylinder pressure entering the cooling system because of head gasket or cracks. The hoses are suppose to get hard as the engine reaches operating temp but you should be able to squeeze them especially after a short drive where the car reached operating temp.

    How do you know if your thermostat is bad in your car?

  • Odd Temperature Gauge Readings. Your temperature gauge should register cold when you first start your car and slowly build up to normal as the engine warms up.
  • Air Temperature Changes.
  • Coolant Leaks.
  • Strange Sounds.
  • Heater Problems.
  • How do I know if my radiator is circulating?

    One way to tell if the coolant is circulating is to look at the radiator filler neck. With the car off or just turned on, it should not be flowing as the thermostat has not been triggered by the car reaching the operating temperature yet. Once the vehicle has warmed up enough you should see coolant start to circulate.

    How do I know if my water pump is circulating? (video)


    How do I know if my thermostat is stuck closed?

    Checking For the Signs of a Bad Thermostat

    Look to see if the coolant is swirling/flowing immediately — that means the thermostat’s stuck open. If the coolant doesn’t flow after 10 minutes or so and continues to be stagnant after the temperature gauge indicates it’s hot, the thermostat’s likely stuck closed.

    Should both radiator hoses get hot?

    Testing stat in place

    Now drive the vehicle until normal operating temperature is reached. Shut off the engine and check both hoses, they should now both be warm. If they are not, your stat is not opening, it will need to be addressed immediately as you’ll run a serious risk of engine damage.

    Should both heater hoses be hot?

    To properly warm the interior of your vehicle, then both heater hoses should be hot. If one is noticeably hotter than the other, then there could be a clog in the hose. In addition, if the heater hoses are cold, this is also a sign of clogged hoses.

    How do I know if my water pump is bad?

  • Coolant Leaking. One of the first signs of a potentially faulty water pump is a puddle of coolant on the ground where you’ve parked your car.
  • Rust or Deposit Build-Up.
  • Noise.
  • Overheating.
  • Steam.
  • How do you diagnose a bad radiator?

  • Your vehicle is overheating. If your vehicle constantly overheats, especially under normal driving conditions, this is one of the most common signs that your radiator is bad or failing.
  • Your vehicle is leaking coolant.
  • Sludge build up in your radiator.
  • Low coolant levels.
  • How do you unclog a cooling system? (video)


    Why is the top of my radiator hot and bottom cold?

    If your radiators are cold at the bottom but hot at the top, this means the flow of hot water is being restricted or redirected; this is usually caused by a build-up of sludge. This means the hot water is not reaching the whole of the radiator while the central heating is on, leaving it cold at the bottom.

    What causes too much pressure in radiator?

    Leaks. The most common cause of radiator leaks is leaky hoses, but you can have leaks in the radiator itself, too, which can be a bigger problem. The coolant continually running from your radiator to your hot, running engine and back again creates a lot of pressure.

    Why does my radiator hose have so much pressure? (video)


    How do I know if my thermostat or water pump is bad?

  • Engine Overheating.
  • Temperature gauge fluctuations.
  • Coolant leak from the front of your car.
  • Steam coming from the front of your car.
  • Nosey or loosen water pump pulley.
  • Coolant leaks around the thermostat housing.
  • How do I test my thermostat? (video)


    How do you unstick a car thermostat?

  • Step 1: Drain the Coolant.
  • Step 2: Remove the Housing.
  • Step 3: Remove the Thermostat.
  • Step 4: Clean the Interfacing Surfaces.
  • Step 5: Put a New Gasket On.
  • Step 6: Install a New Thermostat.
  • Step 7: Reinstall the Housing.
  • Step 8: Refill Your Coolant.
  • Should my water pump be hot?

    If you can touch the pump (not the motor) without feeling any significant heat, then the pump is probably working as it should. But if the pump feels hot to the touch (be careful) or you see steam, then it is running too hot.

    What is the effect if thermostat valve is stuck?

    If the thermostat becomes stuck in the closed position, the circulation of the coolant is blocked so the coolant cannot get to the radiator to be cooled which causes the engine to overheat.

    How do I know if there is air in my cooling system?

    Signs and symptoms of radiator airlock include:

  • Overheating during normal driving.
  • Heater not functioning correctly.
  • Reduced performance.
  • Radiator leakage / losing coolant quickly.
  • How can you tell if heater core is bad?

  • Fog Inside Your Car. Two things could be going on if you have fog inside your car.
  • Sweet Smells in the Car. The sweet smell in your car might not be your perfume or the donuts you’re taking to work.
  • Constant Engine Coolant Loss.
  • Cold Air in the Cabin.
  • Cold Cabin/Hot Engine.
  • What does it mean if both heater core hoses are hot?

    If both heater hoses are hot then the core is getting hot coolant flowing through it. You should check the temperature blend door actuator behind the glove box on heater case to see if it is operating the temperature blend door or not. If the actuator is not moving then replace actuator and retest the heater output.

    Why is my car overheating but it has coolant in it?

    However, if your car is overheating, but the coolant is full, it is probably not a leak. Instead, it may be that it’s having trouble circulating correctly. This can stem from several things, including a faulty water pump, a radiator blockage, a stuck thermostat, or a plugged heater core.

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