Does blocking heater horses causes overheating?

I realized that water was leaking somewhere under the dash on the passenger mats so I assumed it was coming from the heater horses and it was causing the temperature to rise on the dash.I opened the bonnet and blocked the horses then it stopped but now the water is not circulating and the car is overheating.Does blocking water from circulating on the heater horses causes overheating on the engine?
Experienced mechanics share their insights in answering this question :
Hello. If the heater hoses are an integral part of the cooling system, as is the case with most vehicles, then blocking them off can indeed result in engine overheating. Blocking off hoses that are a part of the cooling system can prevent flow, which can quickly lead to overheating, and serious engine damage. Depending on the cooling system setup, some heater hoses can be bypassed, which will cut off flow to the heater core, but still allow flow through the system.

If the heater hoses are leaking, I would recommend having a professional technician, such as one from YourMechanic, visit your location to diagnose the overheating issue and replace any hoses as needed.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

A cracked heater hose can result in leaking coolant. A lack of coolant can cause your engine to overheat. An overheating engine can end in catastrophe. For this reason, if you have any signs of wear and tear, bring your vehicle to an ASE certified mechanic or shop for a repair.
If the coolant isn`t effectively pushed through the cooling system or there`s a radiator blockage preventing adequate airflow, the coolant will overheat.
Clogged Coolant Hose

A blocked coolant hose can indeed cause your engine to overheat. Over time, debris and other road sediments can make their way into your coolant system.

No, blocking of the heater matrix will not cause overheating.
A leaking radiator can cause a lot of harm to furnishings and floors in your home. So a radiator leak should not be left to continue un-repaired for a long time. A leaking radiator can also cause your central heating to stop working due to loss of boiler pressure – leaving your home cold this winter.
Why is my car overheating but it has coolant in it? It could be that the coolant concentration is not correct, or you may have a bad thermostat, a failed water pump, broken drive belt, or a bad radiator or radiator fan.
If your lower radiator hose is kinked, then cooled coolant cannot be cycled back into the engine. This causes temperature levels to rise, and could very easily result in overheating.
A lack of airflow within your HVAC system can cause it to overheat because your components are being forced to work at an increased level.
You can leave your block heater on all night. It won`t do any harm or cause any damage to your engine. It will turn on and off throughout the night to keep your engine warm.
A block heater helps keep your car engine warm while you`re not driving it. Once it gets plugged into a regular 110-volt outlet, the heater warms the engine block as well as internal fluids like the oil and coolant.
If there is a clogged heater core, it will keep the coolant from flowing through the engine, causing it to overheat.
A leaking radiator can overheat the engine, blow head gasket, spark plugs or crack block. In extreme conditions leaking radiator can result in complete engine failure.
Passenger heater not functioning

Your cabin heater relies on the hot coolant that passes through the core. This produces the hot air that gets blown into your car. If your radiator is leaking or is clogged, you may not get the heat you need on that cold winter day. Sometimes, this is just a bad thermostat, too.

If an engine “feels” cold, or “normal” but the dash gauge shows overheating, you could have a faulty temperature sensor and/or gauge. No cabin heat could be due to low coolant, blocked passages, faulty heater control valve and/or faulty blend door(s) in the dash ventilation network.
How long can a car overheat before damage occurs? It only takes 30-60 seconds of overheating for permanent damage to infiltrate a vehicle. As soon as you notice signs of overheating, you need to act. Failure to do so might result in troubles like coolant leaks, damaged radiator caps, and a faulty cooling fan.
Look for signs of coolant leakage—a light-colored residue or stain—around the radiator cap, on hoses throughout the engine compartment (check the ends where they are clamped to other components) and on the radiator itself. If it looks like a hose is leaking near a clamp, try tightening the clamp with a screwdriver.
Driving with a faulty heater core can be risky, as it can lead to overheating and extensive engine damage. Even a clogged heater core can prevent proper coolant circulation, causing your engine to run hot. But if you must continue driving for a short distance, keep an eye on the temperature gauge.
If your radiator is clogged, it can cause damage to the water pump. The water pump is responsible for circulating the coolant throughout the engine. If the coolant can`t flow properly, it can cause the water pump to overheat and fail. This will eventually lead to your engine overheating as well.
Driving with a faulty heater core can be risky, as it can lead to overheating and extensive engine damage. Even a clogged heater core can prevent proper coolant circulation, causing your engine to run hot. But if you must continue driving for a short distance, keep an eye on the temperature gauge.
Dirty Condenser Coils

Condenser coils collect dirt as time goes by. This causes the system to overwork. The HVAC unit will have a hard time conditioning air. This leads to overheating.

Driving with a faulty heater core can be risky, as it can lead to overheating and extensive engine damage. Even a clogged heater core can prevent proper coolant circulation, causing your engine to run hot. But if you must continue driving for a short distance, keep an eye on the temperature gauge.
Block heaters are generally very safe, and provide only the minimum amount of heat required to keep an engine block warm. However, any fault in the electrical cord is a potential source of ignition.
Driving with a faulty heater core can be risky, as it can lead to overheating and extensive engine damage. Even a clogged heater core can prevent proper coolant circulation, causing your engine to run hot. But if you must continue driving for a short distance, keep an eye on the temperature gauge.
Find Local Plumbing Experts

Even a small amount of water leaking from your water heater can cause damage to your floors, sub-floors and walls. A significant flood could lead to hefty repair bills and damage to personal property. Water heater leaks can also be a health concern and lead to mold and mildew.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Does blocking heater horses causes overheating?
ANSWER : Hello. If the heater hoses are an integral part of the cooling system, as is the case with most vehicles, then blocking them off can indeed result in engine overheating. Blocking off hoses that are a part of the cooling system can prevent flow, which can quickly lead to overheating, and serious engine damage. Depending on the cooling system setup, some heater hoses can be bypassed, which will cut off flow to the heater core, but still allow flow through the system.

If the heater hoses are leaking, I would recommend having a professional technician, such as one from YourMechanic, visit your location to diagnose the overheating issue and replace any hoses as needed.

Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.
ANSWER : It sounds like your engine might have a restriction in the cooling system. If the cooling system has a restriction that prevents its flow, this will cause the engine to get hot. The heat is dissipated from the cooling system by means of the radiator.

When a restriction exists sometimes the radiator alone is not enough. The heater core is like a small radiator inside the dash and is also another means of dissipating the heat from the cooling system. So essentially when the heat is on you are introducing a second radiator into the system which will help to cool the engine down.

In order to get this fixed, consider YourMechanic, as one of our mobile technicians can come to your home or office to diagnose the overheating issue firsthand and help you make the necessary repairs.

My car is overheating and my heater is blowing cold air on and off
ANSWER : The heater not working in some cases may be related to the overheating problem you are also having. This may be due to a faulty heater blower motor or potentially a bad heater core. As you may know, the heater core is a small radiator like unit that circulates the hot coolant from the engine through the heater core which then uses this warm coolant to heat the inside of the car with the help of the blower motor that blows the warm air through the vents inside the car. When the cooling system is not properly circulating coolant through the motor, this results in the warm coolant not being pumped through the heater core properly in order to warm the inside of the vehicle.

Engine overheating can be caused by a number of things such as low coolant levels, a faulty thermostat, or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. When your thermostat is not working properly or is stuck closed, this will not allow the coolant to properly circulate through the engine, which may cause the engine temperature to fluctuate erratically or in some cases just remain hot. As mentioned above, this also restricts the warm coolant from flowing through the heater core which uses this to blow warm air into the cab of the vehicle. I would suggest having an expert from Your Mechanic come to your home to diagnose your cooling system.

What causes my car to keep overheating?
ANSWER : Thank you for writing in! Typically the thermostat and water pump are the primary sources of overheating on a 1997 Toyota Corolla. However, since the fluid never left the reservoir, it could be caused by a blockage in the coolant tubes; such as an air bubble. A good bet would be to have one of our local mechanics complete an overheating inspection. This would reduce the frustration of guessing and allow them to pinpoint the source of your issues; so that they could be fixed sooner rather than later.

Best of luck!

Would a blown coolant hose, at heater core, cause loss of power?
ANSWER : Yes, severe overheating will cause loss of engine power and also has a high potential to damage the engine as the pistons scuff the cylinder walls and the exhaust valves stick in the valve guides. If the overheating is severe and prolonged, loss of cylinder compression can occur. To get some idea of the present condition of the engine you can do a compression test on each cylinder and see how the results compare to factory specifications. With regard to the cooling system leak, if you already know the source of the leak, that should be easy to repair. If you do not know the source and/or you want the entire cooling system pressure tested for leaks simply request a cooling system leak diagnostic. Please note that the engine cooling thermostat can be damaged by the high heat that occurs during overheating and it should be replaced. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Overheating and boiling out the reservoir.
ANSWER : Hey there. The next thing you need to do is confirm the thermostat is opening and test to see if the radiator is clogged or not. Begin by warming your car up. Don’t drive it, just let it idle or hold it on a high idle. Depending on the ambient temperature, this can take a half hour or more for the thermostat to open. You will know the thermostat is open by touching the upper radiator hose. The hose that comes off of the thermostat housing. When it begins to get hot, the thermostat is opening. The stat will cycle open and closed during the warm up process. A motor is not fully warm until the stat reaches a point of equilibrium. Meaning, it stays open at a constant amount. If your car begins to overheat and the upper radiator hose does not get hot, you will need to figure out what is going on with the thermostat. It could be installed wrong or even bad. I have had new stats be bad several times.

If the stat opens correctly and your car is fully warm, take it for a quick spin around the block. Come back to a stop in your driveway or other parking spot, turn the motor off, key off, open the hood and reach in and touch the radiator from top to bottom and side to side. You are feeling for cold spots. They will be obviously cold in comparison to the rest of the radiator. It is normal for the lower part of the radiator to be colder than the top. That only means the radiator is cooling as it should.

If after doing these two things your car still overheats, it is time to consider head gasket problems. You can use a block tester kit from your local auto parts store or you can book and appointment with us. Testing for head gasket problems can be cumbersome and only experience will allow you to make an accurate determination. I recommend a having an overheating inspection to have this accurately diagnosed and corrected.

car overheating and heater blowing cold air plus hose to heater core not getting hot
ANSWER : If you replaced all those parts and it still is overheating then you have a radiator that is clogged and/or the fan is not working. You need to see if the upper and lower hose is hot when the vehicle heats up. If this is the case then replace the radiator and check the fan operation to make sure it is working.

Overheats when heater is on, heater blows cold air.
ANSWER : Since you had cooling system work done recently, one possibility is the cooling system is air bound. If air is trapped within the cooling system and not properly bled from the system after a repair, the air can cause the coolant to not circulate properly. This can lead to overheating and no hot air from the heater. Another cause that can simply be coincidence is a stuck thermostat. The function of the thermostat is to allow the engine to reach a certain temperature before opening and allowing coolant to flow throughout the cooling system. If the thermostat is stuck closed and fails to open, the coolant will not flow properly and cause the engine to overheat. The heater will blow cold air because hot coolant is not flowing to the heater core behind the dashboard to provide heat for the interior. Have a certified technician diagnose the engine overheating as soon as possible. Continued driving while overheating can damage the engine.