Pressurised coolant pipes

[adam03031980]

Hi All

It seems when my car gets hot the top hose gets harder is this normal i dont get any loss of water or oil or cross contamination was thinking of bunging in kseal just in case of a head gasket issue.

[gwinter]

The top hose is the one that connects to the thermostat housing? If so then it is normal.
When the engine is cold the thermostat is closed so the top hose is flaccid.
When the engine starts to get hot, the thermostat starts to open and the hose will get flooded with coolant, at the same time the whole cooling circuit is getting pressurised so the top hose will become hard.

[martint]

if the pipe gets that hard that you cant squeeze it a little,then id say you've got a head gasket of water pump prob.
i had this on my other 406. when i took the lid off the expansion tank and looked into it,there was lots of bubbles.after a good run,if its solid hard,(obviously theres always a little give when you squeeze it) i'd say then that theres a prob there

[Gary406]

the top hose is were the coolant travels to the radiator from the engine when the thermostat opens when the coolant is around 82 degrees. so ye when the engine is upto temp that pipe is bound to go hard . thats normal.

if your not getting cross contamination or any loss dont even worry about head gasket fault. just keep an eye on the levels/contamination over next few days. if all seems good then leave it be.

[adam03031980]

I have noticed today the top hose from the thermostat is hot but the one going to the bottom of the radiator is just warm not hot why would that be

[Gary406]

the top hose is were the red hot coolant comes from engine into radiator
the radiator then cools the coolant down
the bottom hose is were the cooled down coolant goes back around the engine

thus,, the bottom is cooler because the radiator is doing its job in cooling the coolant down before being pumped around the cycle again .