Technical Car Experts Answers everything you need: Upper Radiator Hose Hard

Upper Radiator hose hot to touch

If the upper radiator hose was excessively hard and the radiator was cold.

Basically if the radiator hose is hard, there is pressure. The radiator cap is designed to maintain a specified pressure in the cooling system.
Now once the engine cools down, the pressure drops and the hose softens making it safe to remove the cap for inspection.

And if you notice the problem of vehicle overheating then that would normally indicate a plugged radiator.

See below temp sensor located just below upper radiator hose:-----

But if the weather is cold outside the radiator is going to be cooler to the touch after driving, and so is the lower radiator hose.

WHY LOWER RADIATOR HOSE IS COLD TO TOUCH:---
The theory is simple because ,the lower radiator hose is the part from where cooled coolant going back into the engine, so it should be noticeably colder than the upper hose.

YES AGREED:--- In the winter months the lower radiator hose is going to be quite a bit cooler than it would in summer months.That is weather effect.

I suggest you to get the radiator temperature checked on your vehicle.
The only time you could do any temperature checks of the radiator and lower hose is after the vehicle has been driven for few minutes and then parked. After that let the engine idle, and immediately check temperatures.

NOW consider if thermostat is stuck closed .................

If the thermostat was stuck closed you shouldn't get much heat in the upper radiator hose, the lower hose should be hotter than the upper and probably harder. The engine would also overheat.

SO DO YOU NOTICE THESE SYMPTOMS .

IF no then thermostat is Ok,but fault is radiator.

If the radiator was plugged it would cause a hard and hotter upper hose, but would also cause overheating.
So do you notice any overheating after driving few minutes with A/c Turned ON.
If the coolant temperature was running normal when the temperatures were hotter then the radiator is probably ok.

If the a/c won't work then the first thing that would need to be done is check the system pressures. If pressures go too low then the compressor won't engage. Low charge is the most common cause of a/c not working. It could also be the control head, compressor, wiring, compressor relay, powertrain control module, wiring in between, or the orifice tube.

But if temperatures show incorrect then its plugged radiator.

I suggest get radiator inspected.

Drive the vehicle few miles and warm the vehicle up to normal operating temp,then you should be able to touch the top radiator and feel it getting warm. If the engine is hot but the top radiator hose is cold, this means your thermostat is not opening and should be replaced.But if top radiator hose is hot,then thermostat is functioning very correctly.

The coolant running in the engine system is as follows :-----

After driving vehicle for few miles the vehicle engine system gets bit hot,to cool down these heating component and to maintain the vehicles cooling system,coolant runs in to the system.
The coolant runs when thermostat opens.Thermostat sense the heating limit,when its overheat then thermostat open and coolant runs.
Or the other way to make coolant run in engine system is to raise the RPM's to get the thermostat to open. Once it opens and draws in cold coolant from the radiator then the thermostat will close again. Put the vehicle outside in the 30 degree weather and you may have an engine that's partially warm, but the coolant in the radiator is still going to be pretty cold.

The right side of the radiator is always going to be colder than the left side because that's the cooled coolant going back into the engine. The coolant in that side has flowed through a radiator with 30 degree air being forced over it by the (presumably) locked viscous cooling fan.

These theory will help you.

Thanks.

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