Thread: Top radiator hose

It must just be a weak hose & sucking down under the vacuum that's created when the engine cools down.


It'd probably be best to replace them all IMO.

Finaly got the hose and had it fitted yesterday, this morning it was even flatter than the last one ?

Other owners need to watch out for the rear breather hoses from rocker cover to cover on these V8's mine where melted and in three pieces.

mick.

Hi, I fitted a new expansion tank cap the other day and now my radiator hose does this same thing. My hose is brand new so nothing odd with that. It seems to me this is actually a good thing and as it should be. The fluid contracts when cooling down creating a vacuum and expands when it warms up. So in my case with cool engine the hose is sucked at least a bit flat, and with engine at normal temp the fluid pressure in the hose has raised to perfectly where it should be.
My old faulty cap would allow air to be sucked into the radiator (thus no flat hose) and when fluid warmed up the pressure would be excessive due to the added trapped air. It seems what I am getting now is the correct way, pressure cap is not letting any air in, and going from cold fluid to normal operating temp will have the hose go all the way from flat to correct pressure.

So I am very pleased with my hose going flat. This also tells me I have no leaks.