Last updated on July 8th, 2023 at 03:09 pm
Why is My Top Radiator Hose Hot and Bottom Cold? Understanding the workings of the different components of your car is as important as routinely maintaining and servicing the car. To avoid unnecessary worries it is important that you know the normal and abnormal functions of the parts of your car and the cooling system is not left out. Also read: best homemade radiator flush
Why is My Top Radiator Hose Hot and Bottom Cold & Upper Radiator Hose Cold As well
The cooling system consists of the radiator and two radiator hoses (the top radiator hose and bottom radiator hose). These radiator hoses can either be cold or hot depending on different reasons.
In other not to misinterpret the temperature produced by the hoses, I will be telling you what it means when the top radiator hose is cold when the top radiator hose is hot when the bottom radiator hose is hot, and other similar questions.
What Does it Mean When the Top Radiator Hose is Cold?
If you are just starting your car and the top radiator hose is cold then it’s because the thermostat is not open but if it remains cold then the thermostat is faulty or the coolant is not enough. The top radiator hose is not supposed to be cold so witnessing such is not normal and requires that you change the thermostat or refill the coolant.
What Does it Mean When the Top Radiator Hose is Hot?
When the top radiator hose is hot, hot coolant from the engine is passing through it to get to the radiator. What this means is that all is alright and there’s no cause for alarm. Your thermostat is open and the top radiator hose is functioning perfectly as it should. The only time you can worry is if the car is overheating or when the hose is damaged, these are signs of serious problems that should be addressed.
The top radiator hose doesn’t get hot until the thermostat is open. If the top radiator hose gets hot as soon as your start your car then your thermostat is faulty and is always open or not shutting properly. If it doesn’t get hot in time then consider checking the range of the thermostat, ambient temperature, coolant temperature, or the pressure on the engine.
Why is My Bottom Radiator Hose Hot?
Why is my bottom radiator hose hot? Your bottom radiator hose is hot because your thermostat is faulty. The thermostat is meant to supply coolant to the bottom radiator hose to help regulate the temperature of the engine. This means that the bottom radiator hose receives cool coolant and so it is not meant to be hot. It can be warm but not anyway hotter than the top radiator hose.
Why is My Top Radiator Hose Hot and Bottom 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. The top radiator hose carries hot coolant while the bottom hose carries cool coolant and that’s why you are likely to experience this.
As long as your car is not overheating, this is totally normal so don’t worry at all. Another reason why your bottom radiator hose is cold is that your thermostat is closed. Your thermostat doesn’t open and distributes coolant to the bottom hose until the engine’s temperature is increased and no longer within the normal gauge.
Why is My Top Radiator Hose Hot and Bottom Cold BMW x5
BMWs have the better cooling ability and larger radiators and so if your top radiator hose is hot and the bottom is cold and your temperature is normal then there’s no reason to panic or worry; it’s totally normal.
When the difference in the temperature of the top and bottom radiator hoses occurs, it’s possibly because the radiator is absorbing heat from the coolant, the top hose is receiving hot coolant and the bottom hose is receiving cool coolant.
Should Top and Bottom Radiator Hoses Be Hot?
The answer is no, your top and bottom radiator hoses should not be hot. If your top and bottom radiator hoses are hot at the same time then it’s not normal. If both radiator hoses are hot then the coolant received by both of them is hot, and it should not be so. This is caused by a faulty temperature blend door actuator.
The bottom radiator hose is not meant to be hot because it contains coolant that’s entering the engine. While the top radiator hose is normally hot because it contains coolant that is hot and has just finished cooling the engine. When both radiator hoses can be hot because the temperature blend door actuator is faulty. You may love to read this post on fixing Radiator and this other related post too.
Should Radiator Hoses be Hard When Hot?
This is a really good question and the answer is no. Radiator hoses should not be hard when hot, more like fairly hard or you can say firmly. When your engine warms up and the radiator hoses are warm, a firm radiator hose is normal, even when the temperature of the car reduces or increases.
However, if you notice a soft spot on a radiator hose or that the entire body of the hose is soft or spongy then you have a damaged radiator hose that needs to be replaced. Radiator hoses are not meant to be soft but a hard hose can indicate that you have a faulty head gasket that’s allowing coolant to get into the cylinder or air to enter the coolant system.
Lower Radiator Hose Cold Overheating
This is mostly caused by a blocked thermostat. The engines’ of cars have cooling systems to help them run at a normal temperature so if your car is overheating then the first place to look is around the components of the cooling system.
The thermostat, which is a component of the cooling system, controls the amount of coolant that is circulated in the engine. If the lower radiator hose is cold and your car is overheating then definitely your thermostat is not distributing the coolant around the engine as it should. The thermostat should be replaced as soon as possible or it will affect the proper workings of the car.
Upper Radiator Hose not Getting Hot
When your upper radiator hose is not getting hot your thermostat is likely stuck or just malfunctioning. Anyone it is you have to take it seriously. Along with the cold radiator hose you are likely to see an occasional check engine light. The light is an indication that you don’t have enough coolant or you’ve run out of coolant.
A stuck or malfunctioning thermostat means that the engine is overcooling or undercooling. The best solution to this is to replace the thermostat.
Hi dear, my name is Jeffery Ekweghi, and I am a certified mechanic and autobody parts technician. I created this site to share my expertise and experience with car lovers looking to resolve their car-related issues. I am certified in private cars and heavy-duty commercial vehicles. I have worked as a mechanic since 2015 and have experience in vehicle brands like Subaru, Jeep, Toyota, TATA, BMW, Mazda, Honda, Nissan, Kia, TVs, and Others; however, I primarily specialize in Toyota vehicles.
