when the engine goes warm this hose return fluid to the Coolant Reservoir.

but the pressure of returning water is very low. this is mean my radiator get stuck? or its okay to return water with low pressure?

i cant squeeze this hose too ,its like full of pressure. this is okay too or?

enter image description here

  • What is the year/make/model/engine of the car in question? Some vehicles have very hard lines going to/from the engine. Commented May 24, 2019 at 20:21
  • Mazda 3 - 2008 - 2.0
    – Mostafa
    Commented May 25, 2019 at 6:09

2 Answers 2


That tank is only for overflow from the radiator to release coolant when too much builds up, these systems are designed fairly optimally so that is why not very much coolant if any is returned. If you're concerned about the pressure in the lines (with the car off) squeeze the lines then open the reservoir cap and squeeze again if it feels the same then they are hard lines.

  • Flows to and from the overflow tank have very little to do with the radiator ( except to hold overflow when hot and return it when the engine cools down.) Commented Dec 7, 2019 at 22:46

Does the vehicle have a pressure cap on the radiator or is the pressure controlled by the cap on the reservoir? (many cars are) I could not get a clear read on the cap in your picture. Be VERY CAUTIOUS opening radiator caps. Scalding is very painful.

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